Malaysia Responds by Releasing Full Message Log

The missing ACARS message sent over the VHF link.

Today, Malaysia’s Ministry of Transport quietly released the full ACARS message log for MH370. The new log confirms that the traffic logs presented in previous reports were incomplete and edited, as asserted in a previous blog article. This release comes on the heels of a strong denial from Malaysia Airlines stating that it has “provided full cooperation and assistance to all respective authorities”.

Notably, the new log contains an additional ACARS message that was sent from MAS Operations Dispatch Center (ODC) and destined for MH370 over the VHF link. The message was sent at 18:38:51 and was intended to be displayed in the cockpit on a Control Display Unit (CDU), which a pilot uses to perform tasks such as programming the flight computers. The message was not received by MH370, and was re-sent by MAS ODC at 18:39:52, 18:40:42, and 18:41:52, failing each time. The text of the message was:

DEAR MH370. PLS ACK TEST MSG. RGDS/OC.

The new log confirms that there was a renewed attempt to initiate communications with MH370 using ACARS over the VHF link at 18:38:51. The error messages that were generated confirm that the VHF link was not available at that time, likely because MH370 was not logged into ARINC’s server. ARINC was MAS’ service provider for ACARS over VHF.

Also of note is the new ACARS message was sent about a minute before an attempted telephone call over the satellite link at 18:39:56, suggesting an increase in activity at MAS ODC at this time.

The new log contains other traffic between MAS ODC and other ground computers. This data is under examination for additional clues. The new log also confirms that the name of the MAS ODC employee that sent the ACARS messages was redacted from the message logs in previous reports.

Posted in Aviation | 269 Comments »

MH370 Message Logs Were Edited – Updated

ACARS Message Paths ( From “Analyzing Security Breaches in ACARS”, Smith et al., 2017)

Fellow MH370 Independent Group members Don Thompson and Richard Godfrey have found some anomalies in the message logs that were included in Factual Information (FI) released by Malaysia on March 8, 2015, and the Safety Investigation Report (SIR) released by Malaysia on July 30, 2018. The logs from these two reports document the communication between MAS Operations Dispatch Center (ODC) and service providers that route messages over SATCOM and VHF paths, as part of the Aircraft Communications Addressing and Reporting System (ACARS). The anomalies suggest the traffic logs appearing in the reports are not complete, and what appears in the reports has been modified.

A simplified schematic of the ACARS is shown in the figure. For MAS, the service provider for satellite communications is SITA using the Inmarsat network and the service provider for VHF communications is ARINC using a network of ground stations.

Missing Messages Between 18:15:23 and 18:43:33

According to text in both the FI and the SIR, an urgent message from MAS ODC was submitted at 18:03 and then re-transmitted multiple times:

The first message sent to the aircraft cockpit printer from the MAS ODC was at 1803:23 UTC. The ACARS message requested the crew to contact the HCM ACC immediately. The incoming downlink message at 1803:24 UTC showed the message failed to reach the aircraft. Messages are auto transmitted every 2 minutes and the message was retransmitted until 1843:33 UTC but all messages failed to get a response. Automated downlink message by ACARS showed ‘failed’. 

However, the last message from MAS ODC that was shown in both the FI and SIR traffic logs occurred at 18:15:23, and not the 18:43:33 stated in the text. This means that either the explanatory text is wrong, or the traffic logs do not contain all the message traffic.

VHF Messages Not Included

The missing messages could be explained if they were routed via the VHF link. For the ACARS traffic log in the FI, the filter parameters used to extract the message records included only SATCOM traffic for the time period 12:48:00 to 20:00:00, so that if any VHF messages were exchanged, those messages would not be included in the traffic log. (The filter parameters appear at the top of each page of the traffic log in Appendix 1.9A.)

The facts surrounding the ACARS traffic log in the SIR (also Appendix 1.9A) are more suspicious. For Page 1 of the log, the filter parameters did not limit the messages to only SATCOM messages. In fact, at 15:54:31, there is a message submitted by MAS ODC over the VHF link that requests personnel on the aircraft to re-configure the center VHF radio so that future messages would be exchanged via SATCOM. However, starting with Page 2 of the report, the filter parameters used to generate the remaining pages of the report were changed so that VHF messages, if any occurred, were excluded.

The change in filter parameters after Page 1 is unexplained. Two messages received by MAS ODC at 15:54:41 and 15:54:53 appearing at the bottom of Page 1 are repeated at the top of Page 2. The change in filter parameters and the repeated messages are clear evidence that the traffic log in the SIR is actually two reports that were pieced together and presented as a single report.

Edited Text

As it appears in the ACARS traffic log in the SIR, the text message that was sent by MAS ODC at 18:03:23 is:

URGET [sic] REQUEST
PLS CONTACT HO CHI MING [sic] ATC ASAP
THEY COMPLAIN CANNOT TRACK YOU ON THEIR RADAR
I RECEIVED CALL FROM SUBANG CENTRE
PLS ACK THESE MSG
REGARDS

However, the last line of the message appears to have been edited. By examining the ASCII characters embedded in the PDF version of Appendix 1.9A, the following text can be extracted:

REGARDS
MXXXXX

where MXXXXX is an actual name with six letters beginning with M.

There is also a misplaced © symbol on the bottom of the page that appears after the report page number on Pages 2 and later, but properly appears before the name “SITA” on Page 1. This is yet another indication that the traffic log in the SIR was edited.

Request for Complete, Unmodified ACARS Logs

It is disappointing that more than four years after MH370’s disappearance, we are still asking Malaysia to release withheld data. The military radar data is another example of a data set that has never been released in full despite its significance in providing information about how the aircraft was flown after the diversion from the flight plan.

It is important that Malaysia provide a complete, unmodified log of all ACARS communications on SATCOM, VHF, and HF paths for the period between 12:48 and 20:00 on March 7, 2014. This is particularly significant in light of questions surrounding the delayed response of Malaysian authorities after MH370 went missing.

Update on Sept 4, 2018

The Daily Star reports that it has received a statement from Malaysia Airlines about the anomalies in the traffic data logs that were reported in the article above:

A spokesman told Daily Star Online: “Malaysian Airline System Berhad (Administrator Appointed) (“MAS) is aware of the recent media reports alleging anomalies to the traffic data logs in the Safety Investigation Report published by the Malaysian ICAO Annex 13 Safety Investigation Team for MH370. 

“MAS wishes to state that MAS has provided full cooperation and assistance to all respective authorities on the investigation for MH370, including the submission of relevant documents necessary for the investigation.

MAS will continue to cooperate with the Authorities and if necessary, provide any information to them in line with international requirements and applicable laws.” 

Conspicuously absent is an explanation for the missing messages and the edited logs.

Posted in Aviation | 153 Comments »

End-of-Flight Simulations of MH370

Boeing simulations of MH370 at end-of-flight. (Click on image to enlarge.)

Introduction

With the failure of the recent search by Ocean Infinity to locate the debris field along the 7th arc at latitudes as far north as 25S and at widths equal to or exceeding +/- 22 NM, we consider whether it is possible that with the assumption of uncontrolled flight, the plane could have impacted the ocean farther than 22 NM from the 7th arc, and was missed because the search along the arc was too narrow.

At each phase in the subsea search for MH370, the search area was defined by following parameters:

  • A range of latitudes along the 7th arc
  • A width inwards and outwards from the 7th arc

The range of latitudes for the search was determined by analysis of the satellite data, aircraft performance, and drift models. Collectively, these data sets constrain the position that MH370 crossed the 7th arc. Unfortunately, due to the imprecise nature of these data sets, official and independent investigators have proposed a fairly large range of latitudes, and this continues to be the subject of debate.

In a parallel effort by the ATSB, the width inwards and outwards from the arc was estimated by the distance the aircraft could have glided after fuel exhaustion. With the assumption that there were no pilot inputs after fuel exhaustion, this distance was determined by end-of-flight simulations conducted by Boeing based on aircraft conditions requested by the ATSB. The simulations were completed in Boeing’s engineering simulator, which offers high fidelity of the aircraft’s performance. Some of the results of these simulations were presented in an ATSB report entitled MH370 Search and Debris Update, released in November 2016.

Simulation Results

Because of the importance of the simulations in establishing the search width, I asked the ATSB for more details about the conditions modeled and the results of the ten simulations. (Because Boeing conducted the simulations based on conditions requested by the ATSB in support of the search, they are an ATSB product.) Although legal restrictions prevent the ATSB from providing specific details about each of the ten simulations (referred to as Cases 1-10), the ATSB did reveal that the initial speeds varied between M0.75 and M0.83, the starting altitudes were either FL350 or FL400, the initial headings were either 178°, 184° or 190°, and turbulence was either light or moderate. Winds at various altitudes were included in the simulations.

In addition to these general descriptions, the ATSB did provide me with numerical results of the ten simulation runs in the form of X, Y, and altitude in one second increments, where X is the E-W position in NM, Y is the N-S position in NM, and the altitude is in feet. (The ATSB deliberately did not include the latitude and longitude values in these files so that there was no association with a particular crossing of the 7th arc.) The ATSB has permitted me to share these results on this blog so that a broader group of investigators can independently analyze the results. To my knowledge, this is the first time these results have been released to the public.

Although not included in the files, derived quantities such as groundspeed, Mach number, track, vertical speed, vertical acceleration, bank angle, and wing loading are all calculable, although some parameters such as Mach number and calibrated airspeed need assumptions about the wind and temperature fields.

A presentation of the detailed technical analyses of all the simulations would be lengthy and not appropriate for a blog post. However, some generalized observations and results are summarized below:

  • There were two groups of simulations. In the first group (Cases 1,2,5,7,8,9), the autopilot was lost after the flameout of the second (left) engine, which corresponds to a “normal” configuration of the electrical system.
  • In the second group (Cases 3,4,6,10), the electrical configuration was in an “alternate” configuration in which the left generator and left backup generator were isolated with switches in the overhead panel. In this case, when the right engine is running, power is supplied to the left bus from the right bus through the bus tie breaker. However, after the first (right) engine flames out, both main AC busses and both transfer busses lose power, which causes the flight control mode to transition to “secondary” and the autopilot and autothrottle disengage, even as the left engine continues to provide thrust.
  • The SATCOM’s log-on request at 00:19 is assumed to occur two minutes after the loss of the autopilot. (The two minute interval assumes the APU would take one minute to start supplying power, and the SDU would subsequently take one minute to power up and request a log-on to the satellite.) The ATSB has adjusted this position in all the simulations so that the two-minute mark occurs at the same X,Y values, and the paths can be compared. The two-minute mark serves as a reference position (labeled with “2 mins” in the figure above).
  • For all ten simulations, the paths stay within a distance of 32 NM from the reference position. However, since all paths are curved, the farthest impact point from the 7th arc is only about 15 NM, and depends on the track angle between the initial path and the arc tangent.
  • There were five simulations (Cases 3,4,5,6,10) in which the rate of descent exceeded 15,000 fpm and the downward acceleration exceeded 0.67g, which are the values indicated by the two final values of BFO. This included all four cases with the “alternate” electrical configuration, and one with normal configuration. The maximum downward acceleration for these cases ranged between 0.87g and 1.30g.
  • For the five simulations (Cases 3,4,5,6,10) with high descent rates, the impact occurs within 14 NM from the reference position, and about the same distance from the 7th arc, depending on the track angle between the initial path and the arc tangent.
  • For the five simulations (Cases 3,4,5,6,10) with high descent rates, the descent rate of 15,000 fpm and the downward acceleration of 0.67g occur at different times, and are not predicted to occur at the time of the log-on. If the impact distance is measured from the point at which the descent rate first exceeds 15,000 fpm, the distance ranges between 4.7 NM and 7.9 NM.
  • In none of the simulations did the plane fly straight with level wings after the autopilot was disengaged. Ultimately, the magnitude and direction of the bank that develops is the net effect of a many factors, including thrust asymmetry, TAC, manual rudder input, weight imbalance, aerodynamic asymmetry, and turbulence, with the dihedral effect of the wings and center-of-mass tending to restore the bank to zero.

Simulation of Alternate Electrical Configuration

Case 6: A simulated end-of-flight path for the left generators turned off before fuel exhaustion. (Click on image to enlarge.)

The four simulations (Cases 3,4,6,10) with the alternate electrical configuration are interesting because in all cases, the descent rates and downwards accelerations exceeded the values suggested by the final BFOs, and the high speed descent is achieved within minutes of loss of the autopilot. To further illustrate the sequence of events, we consider Case 6, with initial conditions of a groundspeed of 425 knots at an altitude of 35,000 ft, and shown in the figure above.

When there is no more fuel in the right tank, the right engine coasts down and the left engine speed increases to full thrust. The loss of AC power causes a transition to secondary control mode, and the autopilot and the autothrust are disengaged. As the right engine coasts down, the automatic thrust asymmetry compensation (TAC) will apply left rudder, but the amount of rudder does not change after the flight control mode degrades to secondary.

After the right engine flames out, there is a slight turn to the right, which means the rudder position does not completely balance the yaw from the resulting thrust asymmetry. It is possible that the transition to secondary control mode occurs before the TAC can apply sufficient rudder input to fully compensate for the thrust asymmetry of no right engine thrust and full thrust of the left.

At some point, the remaining fuel in the left tank is exhausted, and the left engine shuts down. With both engines producing no thrust, the left rudder position now causes a steep turn to the left, and the plane descends. At the point it reaches 27,000 ft, the descent rate is 15,000 fpm, and it has achieved a downward acceleration of 0.3g over the preceding eight seconds. The plane levels off at about 19,000 ft, and then begins to again rapidly descend, reaching a descent rate of 15,000 fpm at about 18,000 ft, and impacting the sea about 3.3 NM from this point. The impact distance from the earlier point of reaching a descent rate of 15,000 fpm is about 7.9 NM.

Discussion

[Phrases in italics were added on Aug 21, 2018 for clarity.]

If we consider that the end-of-flight Boeing simulations were representative of the actual conditions of MH370, we have three possibilities:

  1. If the flight was uncontrolled after fuel exhaustion, and if we ignore the final BFO values, the plane impacted no farther than about 15 NM from the 7th arc.
  2. If the flight was uncontrolled after fuel exhaustion, and if the descent rates suggested by the final BFO values are valid, then the aircraft impacted no more than about 8 NM from the 7th arc.
  3. If the flight was controlled after fuel exhaustion, an efficient, stable glide starting at about 40,000 ft could have achieved a distance of 120+ NM from the 7th arc.

Possibilities (1) and (2) suggest the next search should occur along the 7th arc north of 25S latitude at a width of about +/-25 NM.  The +/-25 NM is an estimate that includes uncertainty in the simulation models and uncertainty in the final BTO values. 

Because possibility (3) requires pilot inputs after fuel exhaustion, if this occurred, we have to assume that pilot inputs also occurred during the powered part of the flight after 19:41. As such, there would be no reason to believe that paths reconstructed with the assumption of automated flight with no pilot inputs are representative of the path actually flown. The large width (+/- 120 NM) and the difficulty in objectively constraining the crossing latitude of the 7th arc would make it difficult to define a manageable search area without additional information.

Until additional information or insights become available, it will be difficult to establish a new search area.

Posted in Aviation | 434 Comments »

MH370 Safety Report Raises Many Questions


As expected, the Safety Investigation Report on MH370 offered no explanation on the cause of the disappearance. “The answer can only be conclusive if the wreckage is found,” Kok Soo Chon, head of the MH370 safety investigation team, told reporters. However, Malaysian investigators did surmise the plane was intentionally diverted, likely due to unlawful interference by a third party. The Malaysia investigators also believe the disappearance could not have been a deliberate act by the pilots based on their background, training, and mental health.

As all the passengers and crew were cleared,  who was this third party that diverted the plane? How can Malaysian investigators ignore that the captain had the best opportunity and capability to divert the plane? How does the compressed timeline of the diversion fit any other possibility if the diversion was intentional? It is understandable that the Safety Report did not apportion blame to the captain. However, it is not understandable that the report deflected blame to an unnamed third party.

The report, including the appendices, is 1,423 pages, and it will take some number of days for independent investigators to thoroughly pore over the entire contents and provide thoughtful comments and analysis. However, based on an initial review, there are some technical questions and inconsistencies that are apparent:

Radar data

The report provides more details about the radar data, but Malaysia fails to provide the raw military data that would allow an independent review. (The civilian radar data was previously made available through an unsanctioned release, and published in a previous blog post.) The military radar includes speed and altitude data, in addition to latitude and longitude at each capture. However,  some of the variations in speed and altitude are beyond the capabilities of the plane. For instance, the measured speed and altitude at 18:01:59 UTC are 589 knots and 58,200 ft. One minute later, the speed and altitude are  recorded as 492 knots and 4,800 ft. The investigative team was warned that the altitude and speed extracted from the data are subjected to inherent error. The only useful information obtained from the Military radar was the latitude and longitude position of the aircraft as this data is reasonably accurate. How the military radar data can be so far out of calibration is unexplained.

After all this time, we still can’t be sure what radar data is available as MH370 passed over the Malacca Strait. According to the main body of this report, the radar target disappeared at 18:01:59 near Pulau Perak, and re-appeared at 18:15:25 along airway N571 between waypoints VAMPI and MEKAR, disappearing at 18:22:12 about 10 NM past MEKAR. However, in an Appendix 1.6E, Boeing reports that after 18:01:59, there was only one capture at 18:22:12. It appears that the radar data provided to Boeing is consistent with the data provided to the ATSB, but Malaysia claims there were additional captures along airway N571 between 18:15:25 and 18:22:12.

We also can’t be sure when the unidentified radar targets captured over the Malay peninsula were first recognized as MH370. According the Safety Report, On the day of the disappearance of MH370, the Military radar system recognised the ‘blip’ that appeared west after the left turn over IGARI was that of MH370. Even with the loss of SSR data, the Military long range air defence radar with Primary Surveillance Radar (PSR) capabilities affirmed that it was MH370 based on its track behaviour, characteristics and constant/continuous track pattern/trend. Therefore, the Military did not pursue to intercept the aircraft since it was ‘friendly’ and did not pose any threat to national airspace security, integrity and sovereignty. In light of the claim that the military was fully aware of the path of MH370, it is not explained why the initial Search and Rescue operations were coordinated in the South China Sea to the east of Malaysia, and proceeded for some number of days before they were moved west of Malaysia to the Indian Ocean.

Pilot Simulator Data

Citing the Royal Malaysian Police (RMP) report from May 2014, the Safety Report says It was also discovered that there were seven ‘manually programmed’ waypoint4 coordinates … that when connected together, will create a flight path from KLIA to an area south of the Indian Ocean through the Andaman Sea. These coordinates were stored in the Volume Shadow Information (VSI) file dated 03 February 2014. The function of this file was to save information when a computer is left idle for more than 15 minutes. Hence, the RMP Forensic Report could not determine if the waypoints came from one or more files.

What is not mentioned is that certain values that were common to the data sets indicate that these files were likely from the same simulation. This was first documented in a technical paper I co-authored with Yves Guillaume, and summarized in a previous blog post. Also included in the previous blog post were statements from the ATSB indicating that the chronological order of the data sets matches a flight departing KLIA, flying over the Malacca Strait, continuing past the Andaman Islands, turning to the south, and exhausting fuel in the SIO, in the same order that the progressively depleting fuel levels suggest. The time values also indicate that the flight session lasted for about one hour, suggesting the position of the aircraft in the simulation was manually advanced and the fuel levels manually depleted.

There are other strange facts surrounding the simulator data. For instance, Malaysia does not explain why only fragments of the data files were recovered, as the reconstruction of the entire contents of the data files should have been possible using the data in the Shadow Volume. The missing portions of the data files include important information that would be stored in the flight management computers (FMCs), including flight plans. Also, the time stamp data that was included in the data files that were made available to the ATSB by the Australian Federal Police was not included in the RMP report.

The RMP conclusion that there were no unusual activities other than game-related flight simulations is odd considering the extraordinary coincidence that a simulated flight including a departure from KLIA and ending in fuel exhaustion in the SIO was recovered after the disappearance.

Investigation of the Flaperon

After the flaperon was recovered from Reunion Island, which is sovereign territory of France, French scientists performed tests to determine the flaperon’s provenance, to analyze the attached marine biology, to determine its buoyancy and other hydrodynamic characteristics, and to investigate the damage to determine how the flaperon separated from the aircraft. To the French team, it appeared that the flaperon impacted the water while still attached to the aeroplane and that at the time of the impact it was deflected. The implication is that water forces from an attempted ditching caused the flaperon to separate rather than in-flight during a high speed descent. The French were careful to advise that this is only an hypothesis because of the limited data made available to them by Boeing, and because of the complicated dynamics of the impact mechanics.

Nonetheless, if it can be proven that the aircraft was in a controlled descent at the time it impacted the ocean, the distance from the 7th arc could be greater than 120 NM, as there could have been a long glide after fuel exhaustion. A controlled descent after fuel exhaustion would also leave open the possibility of pilot navigational inputs after 19:41, and possible paths would include crossing the 7th arc over a large range of latitudes. These unknowns would make it very difficult to define a new search area of a manageable size. For this reason, it is critical that mechanism that led to separation of the flaperon be determined with a higher level of certainty.

First Officer’s Cell Phone Connect

The First Officer’s cell phone registered on a cell tower as MH370 passed to the south of Penang Island. Although it would be unlikely that a cell phone connection would persist long enough to complete a call, a cell phone registration of short duration and at cruise altitude is not that uncommon.

Considering the large number of Malaysian passengers and crew that were likely carrying cell phones compatible with the Malaysian cell network, and with some fraction of those phones likely in an operational configuration during the flight, it is odd that other cell phone registrations did not occur. It is unexplained whether or not a systematic review of the cell phone numbers of all passengers and crew was ever performed.

Final Comments

It is unlikely that another search for MH370 will occur unless a case can be made that there is a reasonable probability of success. Unfortunately, the Safety Report raises more questions than it answers, and it will be difficult to use the information in the report to define a search area of a manageable size. The answers to some questions will not be known until the flight data recorder is recovered. However, the answers to other questions are known to Malaysian authorities today. Any remaining chance to find MH370 squarely rests on the willingness of the new Malaysian administration to cooperatively work with official and independent investigators.

Posted in Aviation | 711 Comments »

Simulated drift of the flaperon after 389 days from 22S latitude (Godfrey).

Introduction

Fellow MH370 Independent Group (IG) member Richard Godfrey has completed a new drift analysis that suggests that MH370 might have crashed further north on the 7th arc than was previously searched. Richard concludes that the recovered aircraft debris from the beaches of East Africa could have originated from potential impact sites as far north as 20.5°S latitude. He is recommending that a new subsea search cover the part of the 7th arc between 25°S and 20°S latitudes based on his new drift analysis. As further justification for a new search to the north, he also cites the reconstructed flight path over Cocos Island ending at 22°S that we discussed in the previous post.

Discussion

The new drift analysis highlights the timing and location of the discovery of four parts that were found with barnacles still attached. These pieces are particularly important because the presence of marine life on a part suggests that the timing of the discovery was close in time to the arrival of the part.  Any marine life that is attached to a beached part either falls off or is picked off due to decomposition and scavenging, so the presence of barnacles is a good indicator that the part was recently beached.

The four parts found with barnacles that were considered in the drift analysis were:

  • The flaperon found on Reunion Island after drifting about 508 days
  • The fragment of the engine cowling (“Roy”) found in Mossel Bay, South Africa, after drifting about 655 days
  • The fragment of the cabin divider found on Rodrigues after drifting about 753 days
  • The outboard flap found in Pemba, Tanzania, after drifting about 835 days

The drift analysis uses the database of buoy positions that are tracked as part of the Global Drift Program (GDP). The data sets from 96 buoys were used to build a model of the Indian Ocean with a spatial resolution of 1° of latitude and longitude, and 1 day of temporal resolution. Both drogued and undrogued buoys were considered. For the flaperon, the drift model also includes an additional 10 cm/s and 1.5% of wind, at an angle to the left of wind at 16°, which were the values that were experimentally measured by CSIRO using a replica of the flaperon.

The figure below (adapted from Richard’s paper) shows the expected time for the flaperon to reach the longitude of Reunion Island for a range of impact latitudes along the 7th arc. Also shown by the shaded area is the actual time (+/- 50 days) for the flaperon to reach Reunion Island. The model predicts that starting latitudes are far north as 19S are possible.

Number of days for the flaperon to reach the longitude of Reunion Island for a range of impact latitudes on the 7th arc. The actual time (+/- 50 days) is shaded. (Adapted from Godfrey)

Richard also considered when debris is predicted to arrive on the shores of the African mainland for various starting latitudes along the 7th arc. The results are shown in the figure below. Also shown by the shaded area is the range of times corresponding to the actual arrival of the engine cowling fragment and the outboard flap, again bounded by +/- 50 days. The model again predicts that starting latitudes are far north as 19S are possible.

Number of days for debris to reach African mainland for a range of impact latitudes on the 7th arc. The actual time (+/- 50 days) is shaded. (Adapted from Godfrey)

Conclusions

The new paper on drift modeling of MH370 debris is interesting in that it gives special attention to those parts found with barnacles still attached, which allows us to estimate the arrival time with better accuracy than for other parts found with little or no marine life.  The paper provides justification for continuing the search further north along on the 7th arc.

Readers interested in learning more about the methodology and the results of the drift model should consult the full paper.

Posted in Aviation | 165 Comments »

An MH370 Flight Path Ending Further North on 7th Arc

Runway on Cocos Island.

Introduction

Now that the recent search effort conducted by Ocean Infinity has ended without finding MH370’s debris field on the seabed, we continue to re-evaluate the evidence and consider other possibilities.

Many researchers that have reconstructed flight paths assume that the aircraft was on autopilot after 19:41. This leads to flight paths that cross the 7th arc at 26S or further south. Now that the 7th arc has been searched as far north as 25S and at a width of at least +/-22 NM, we have to consider the following possibilities:

  1. There are automated flight paths that end north of the 25S latitude that have not been previously considered.
  2. The aircraft was actively piloted after 19:41.
  3. After fuel exhaustion, the aircraft glided without pilot inputs and impacted further from the 7th arc than was searched.
  4. After fuel exhaustion, there was an actively controlled glide that ended outside of the areas searched.
  5. The debris field was scanned but not detected.
  6. The BTO data set was somehow corrupted, and we are not properly interpreting it.

Although we cannot completely dismiss any of these possibilities, and each should be further explored, this article addresses the first in the list.

The challenge in finding automated paths ending further north than 26S is that the reconstructed paths need to curve to the left and decelerate to satisfy the BTO. What follows is one way this can occur while the aircraft is navigating on autopilot with no pilot actions after 19:41.

The automated flight path assumes that the flight computers were programmed to pass near Car Nicobar Airport (ICAO: VOCX) and fly towards Cocos Island Airport (ICAO: YPCC) with an intention to land there. (A route that includes flying towards VOCX, YPCC, and other airports was previously considered by Richard Godfrey.) Here, we assume that after programming the flight computers for a landing at YPCC, there were no further pilot actions. Furthermore, we consider that approaching YPCC, the automated flight plan caused the aircraft to turn to the left to align with the runway, to decelerate, and to fly over and continue past YPCC. This combination of left turn and deceleration is required to match the BTO data.

There are several explanations for why the flight computers might have been programmed for a landing at Cocos Island and then that landing not completed. One explanation is the pilot became incapacitated.  Some possibilities for incapacitation include a physical challenge from crew or passengers, or the aircraft was hit by hostile gun fire leading to rapid decompression of the fuselage. The possibility that MH370 was pursued by a Malaysian fighter jet was the subject of a previous article, and may have relevance.

Assumptions and sequence of events

The reconstructed flight paths are based on the following:

  1. FMC was programmed for automated flight between Car Nicobar (VOCX) and a landing at Cocos Island (YPCC) using the LNAV and VNAV autopilot modes at cruise altitude.
  2. The FMC was programmed for landing on Runway 15 using the RNVZ15 standard approach with PCCNE selected as the transition waypoint. (The selection of a transition waypoint does not significantly change the results.) In the aircraft’s navigation database, the approach would be defined as: APPROACH RNVZ15 FIX PCCNI AT OR ABOVE 1500 FIX PCCNF AT OR ABOVE 1500 FIX OVERFLY PCCNM 55 RNW 15 FIX PCCNH TRK 152 UNTIL 1500; TRANSITION PCCNE FIX PCCNE AT OR ABOVE 1500 SPEED 210
  3. Flying between VOCX and YPCC, the VNAV target speed was either LRC, ECON, the last speed constraint from the flight plan, or a speed selected in a VNAV screen. There was no speed intervention, i.e., the MCP speed window was closed.
  4. At the Top of Descent (ToD) about 110 NM from PCCNE, the pilot did not reset the altitude to a lower altitude, which constrained the aircraft to continue at the existing cruise altitude.
  5. At about 38 NM from PCCNE, the descent path calculated by the FMC would have reached 10,000 ft. The target speed would have reduced to 240 KIAS in accordance with the FMC’s default speed transition at 10,000 ft, even though there was no change in altitude from the cruise altitude.
  6. Approaching PCCNE, the VNAV target speed was automatically reduced to 210 KIAS in accordance with the programmed speed restriction at PCCNE, or the minimum maneuver speed (MMS), whichever is greater, with the aircraft remaining at cruise altitude. MMS was about 210 KIAS.
  7. At PCCNE, the aircraft turns towards waypoint PCCNI, and aligns with the runway on a track of about 152°M.
  8. Upon passing the runway and the final waypoint PCCNH, the FMC reaches an END OF ROUTE, the plane continues at the cruise altitude on a constant magnetic heading until fuel exhaustion. As the speed constraint for the runway is less than the MMS, the MMS becomes the target in the MCP speed window, and this speed is maintained for the remainder of the flight until fuel exhaustion.

The input variables that were varied are:

  • The starting position at 19:41. Since we are constraining the path to a great circle between VOCX and YPCC, only the latitude at 19:41 needs to be specified.
  • The VNAV mode, i.e., whether in ECON, LRC, or constant airspeed. If in ECON mode, there is an associated Cost Index (CI), which is based on the cost of fuel and time. For ECON mode at a given CI, and for LRC mode, the optimum speed varies as a function of aircraft weight and altitude. VNAV also commands throttle and pitch so that the speed and flight path adhere to any speed and altitude constraints programmed in the flight plan or selected in the VNAV screen.
  • The cruise altitude, which is assumed to be constant until the flame out of the first engine.

As the aircraft passes YPCC on a constant magnetic heading, the magnetic variation tends to slightly curve the flight towards the east as the magnetic variation increases from about 2.4°W near YPCC to about 2.7°W near 22 S latitude on the 7th arc. On the other hand, after passing YPCC, the wind is initially towards the west at 19 knots and 266°T, but weakens and changes direction towards the east between 16S and 17S latitudes so that at 18S latitude, it is about 10 knots at 81°T.

Results

A range of paths can be generated by sampling the input space and incorporating the uncertainty in BTO values, BFO values, wind, temperature, and MMS. One solution that is shown below is at FL320 and M.819, with a position at 19:41 about 25 NM south of VOCX.

Automated flight path passing over YPCC.

At the time the aircraft reaches the approach waypoints for YPCC, the MMS is about 210 KIAS, and remains at this speed for the rest of the flight. The aircraft would cross the 7th arc at about 22.0S latitude, which places it well north of what was previously searched.

The following table summarizes the flight parameters after 19:41 for this case (M.819 at FL320). The RMS error for the BTO is 26.0 μs and the RMS error for the BFO is 6.4 Hz with a mean error of -5.1 Hz:

Discussion

Ocean Infinity has expressed an interest in continuing the subsea search for MH370 at some time in the future. Options include

  • Scanning along the 7th arc at latitudes north of 25S
  • Scanning along the 7th arc at previously searched latitudes, but at a greater distance perpendicular to the arc
  • Re-scanning areas where the detection of the debris field might have been missed

Ultimately, the decision where to search must consider other aspects such as end-of-flight dynamics, drift modeling, surface search efforts, and fuel consumption, none of which were considered here. As such, this article is not a recommendation as to where to search next. Rather, this article was meant to provoke discussion about the possibility of an automated flight ending much further north on the 7th arc than was previously considered. Also, the article provides additional data for scenarios in which the pilot intended to land on Cocos Island but did not take the actions required for landing.

Acknowledgement

I am grateful for comments received from Mike Exner, Richard Godfrey, and @Andrew.

Update on July 4, 2018

Here are the results for another path, including the results from a fuel analysis. The path assumes that after a hold at Car Nicobar at FL250, the aircraft proceeds towards YPCC at FL320 and M0.8, and crosses the 2nd arc about 53 NM south of Car Nicobar. The following table summarizes the flight parameters after 19:41 for this case (M.8 at FL320). The RMS error for the BTO is 25.3 μs and the RMS error for the BFO is 6.0 Hz with a mean error of -4.6 Hz:

The fuel model is an improved version of a model I developed over one year ago, and is based on the drag-lift curves for a B777-200 that was presented in Ed Obert’s textbook entitled “Aerodynamic Design of Transport Aircraft”, with fuel flow – thrust relationships developed from descriptions in Walt Blake’s Boeing textbook entitled “Jet Transport Performance Methods”. Previously, I found that the model predicted the tabulated fuel flow data for LRC and Holding speeds with an RMS error of about 1%. The present model improves the prediction by introducing a correction factor that forces the calculated fuel flow to the exact tabulated values at the LRC and Holding speeds, and linearly varies the correction factor as a function of Mach number between those speeds. As such, the accuracy of the model between the Holding and LRC speeds should be very high. Also added to the model are calculated flow rates for climbs and descents, which assume full thrust and idle thrust, respectively, with vertical speed and flight path angle (FPA) directly calculated from the thrust and drag models.

The results of the fuel analysis are tabulated in this Excel file, which includes the remaining fuel at one minute intervals from 17:07 UTC until fuel exhaustion. At each time, the fuel flow is calculated as a function of weight, altitude, speed, and temperature. Assuming both engines fail at exactly the same time, fuel exhaustion is predicted to occur at 00:14 UTC. If the right engine fails before the left, the final (left) engine will fail at about 00:17. The predicted time of fuel exhaustion is consistent with our assumed fuel exhaustion at 00:17, considering the uncertainty in the actual flight path, the engine PDAs, and the meteorological conditions.

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Sixty Minutes Australia Story on MH370 is a Sensation

On Sunday night, Sixty Minutes Australia aired an episode on the disappearance of MH370. Included was a panel of five experts, consisting of Canadian crash investigator Larry Vance, US air safety expert John Cox, British airline captain Simon Hardy, former ATSB commissioner Martin Dolan, and Australian oceanographer Charitha Pattiaratchi. Before airing, the episode was heavily promoted with teasers claiming there would be “groundbreaking revelations”, the “passengers’ final seconds”, and a “forensic twist”.

Unfortunately, after watching the episode twice, I found nothing in the way of new evidence or insights. What I did see were some of the experts confusing speculation with facts, and cherry-picking evidence to support their pet theories while carefully omitting contradicting evidence.

Despite the obvious shortcomings of the episode, the mainstream media is covering it extensively with headlines like “Experts Have Finally Solved the Mystery Behind the MH370 Disappearance”. The sensational nature of the story makes it attention-grabbing, and hiding behind the Sixty Minutes brand name, there is little or no attempt to fact-check.

A large part of the episode was devoted to Larry Vance’s theory that the captain hijacked the plane and flew it to the SIO to hide it. That plan included a successful ditching with the engines running and the flaps extended, leading to the sinking of the aircraft with the fuselage intact. (This “new” theory was already presented by Mr Vance in a Sixty Minutes story that aired in July 2016.) This ditching would produce only a small amount of floating debris. Mr Vance also refers to the damage to the trailing edges of the right flaperon and right outboard flap and the lack of damage to the leading edges of those parts. He believes this pattern of damage conclusively shows that there were hydrodynamic forces as those parts were dragged across the water surface during the ditching.

What was omitted is that we do have pieces of evidence that refute some of Mr Vance’s claims, and should at least cast a shadow of doubt on many of his conclusions. Briefly,

  • Crash investigators at the ATSB have examined the right flaperon and the right outboard flap that were recovered and determined that some damage on both parts was caused by mutual contact, and the location of that contact could only occur with the flaps retracted.
  • Recovered parts from the passenger cabin show deformation from a high energy impact and not a successful ditching.
  • The final log-on of the SATCOM at 00:19 suggests there was a disruption of electrical power to the SATCOM, which is consistent with fuel exhaustion of both engines, and not a ditching with the engines running. It’s not clear in his scenario what caused the log-on.
  • The damage to the trailing edges of the flaperon and flap could have been caused by aerodynamic forces occurring during a high speed descent. The lack of damage to the leading edges can be explained by separation of these parts from the aircraft prior to impact with the ocean.

Strangely, in the episode, Martin Dolan does not challenge Mr Vance’s scenario with the contradictory evidence published by the ATSB. Perhaps those challenges were made, and they were not included in the episode. Or, perhaps Mr Dolan is not sufficiently familiar with the technical analyses of the ATSB where he could confidently refute some of Mr Vance’s claims.

The theories of Simon Hardy also were featured in the episode. Mr Hardy, like Mr Vance, believes that the captain hijacked the plane, but he believes the plane glided a long distance after fuel exhaustion rather than a ditching with the engines running. The possibility of a glide suggests a crash location at a distance from the 7th arc that is well beyond what was searched. His claim that military data shows that MH370 was flown along the borders of Malaysia and Thailand is presented as shocking new evidence, when in fact the turnback flight path across the Malay peninsula has been known to the public within weeks of the disappearance, and the implications have been widely discussed. (The precise flight path flown as captured by civilian radar has only been recently published, and was the subject of the preceding blog post.) Mr Hardy also demonstrated on a flight simulator that it is possible for a skilled pilot to recover from a high speed descent that matches the satellite data, which was not in dispute, although he does downplay the importance of gently working the controls and applying speedbrakes to help arrest the descent and prevent overloading of the lift and control surfaces. (Why a pilot would first enter into a steep descent, then recover and maximize the gliding distance, was not explained.) At another point, he claims to know exactly where MH370 crashed, although he neglects to state that all drift models suggest a crash point much further north.

In the episode, Mr Hardy once again promotes his theory that MH370’s flight path as it flew south of Penang Island shows indication that the captain turned to the right, lowering the right wing, and allowing the captain to have a final, sentimental view of Penang before leaving Malaysia forever. In fact, using the recent radar data, we can deduce that at the point of closest approach to Penang, MH370’s wings were either level or only slightly banked. After passing Penang, there was a turn to the right followed by a turn to the left, but to conclude that this was an emotional farewell is pure speculation, and weakens his theories.

Although I disagree with some of Mr Vance’s and Mr Hardy’s conclusions, I am in general agreement that the disappearance was likely an intentional diversion and not likely the result of a series of mechanical failures. After reviewing many accident scenarios proposed by some very bright minds, I have yet to see an accident scenario that did not require a sequence of very unlikely events. On the other hand, a deliberate diversion requires no unlikely events, even if we might not understand the motivation for many of the intentional actions.

If the diversion was intentional, the captain becomes the likely suspect, as he had the skill and the best opportunity to divert the aircraft. In addition, as discussed and analyzed in a previous blog post, the incriminating evidence found on his home computer of a simulated flight to the Southern Indian Ocean would be an extraordinary coincidence if the captain was not somehow involved in the disappearance.  There is certainly not enough evidence for a legal determination of guilt. However, I believe there is sufficient evidence to make him the prime suspect.

Perhaps the Sixty Minutes episode did have value in that it did not shy away from presenting what many believe is the most likely scenario, even if some of the conclusions from the experts were either unfounded or premature.

The episode comes at a time when Ocean Infinity is in the final weeks of the seabed search for MH370. If not found, and if there is a willingness to conduct additional searches next year, a decision has to be made whether to prioritize areas along the 7th arc that are further north, or to revisit previous latitudes but search further away from the arc, or to revisit areas that might have been insufficiently scanned previously.  A strong case for the possibility of a glide after fuel exhaustion would support searching wider (+/- 100 NM) from the 7th arc.  Unfortunately, the size of the search becomes unreasonably large unless there is rationale to support a narrow range of latitudes along the 7th arc.

On a final note, I have been asked whether the defeat of the incumbent party in the recent Malaysian elections could lead to a more thorough investigation of the events surrounding MH370. Although it is possible, the winning candidate and former Prime Minister, Mahathir Mohamad, has previously supported the unlikely theory that MH370 was diverted remotely using secret Boeing technology embedded in the flight controls. While this might indicate his willingness to challenge the official narrative, it also might demonstrate his willingness to use the MH370 for political gain rather than seek the truth. Meanwhile, his heir-apparent, former Deputy Prime Minister Anwar Ibrahim, had family and political ties to MH370’s captain, and those ties might taint future investigations. On a positive note, it is possible that any whistleblowers that were previously reluctant to come forward might now feel less threatened.

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The Civilian Radar Data for MH370

Civilian radar data after transponder was disabled. (Click to enlarge.)

We know that MH370 was captured by civilian and military radar sites before and after the transponder was disabled at 17:21 UTC. However, Malaysian authorities have chosen to release these data sets only as low resolution images that have imprecise position information with few timestamps. The DSTG did choose to publish in its Bayesian analysis the speed and track data that was derived from radar data that was provided to them by Malaysia. However, the DSTG presented the speed and track data after applying a Kalman filter to remove noise. It’s unknown whether that Kalman filter produced artefacts in the graphical presentation of that data.

We now have what we believe are the data sets for the primary surveillance radar (PSR) and secondary surveillance radar (SSR) from Malaysian civilian radar assets. The PSR data is of particular significance because it provides additional insight about how MH370 was flown after the transponder was disabled at 17:21 UTC. The data was publicly released by fellow IG member Mike Exner. The military radar data remains unavailable.

The data begins at 17:30:33 when the civilian radar installation at Kota Bharu Airport (WMKC) detected MH370 traveling back towards the Malay peninsula about 58 NM from shore. The last radar target was captured by the civilian radar installation at Butterworth Airfield (WMKB) after MH370 had passed to the south of Penang Island and was tracking northwest up the Malacca Strait towards Pulau Perak.

Some initial observations about the data:

  1. The PSR data is similar to the civilian radar data that was graphically presented in the Factual Information (FI) from March 2015. However, while the last civilian radar capture in the FI was at 17:51:47, the new data set has captures until 18:00:51.
  2. The path derived from the Kota Bharu radar data is not straight. More analysis is required to determine if this waviness indicates that there were pilot inputs from manual flying, pilot inputs to the selected heading with autopilot engaged, or inaccuracies of the radar data.
  3. The path was tangent to a 5 NM radius for both Kota Bharu and Penang Airports. This may indicate that these airports might have been displayed as fixes in the navigational display (ND) with a radius of 5 NM and used as navigational references.
  4. After passing to the south of Penang Island, the plane first tracked towards 301ºT, and then changed to 291ºT, which aligned with Pulau Perak and roughly towards VAMPI.
  5. The groundspeed data as derived from the radar data is noisy, reflecting uncertainty in the value of the timestamp as well as the range and azimuth for each capture. In light of the uncertainty, the average speed was calculated for five of the six segments of radar captures, and shown by the red line in the figure below. (The time interval of the shortest segment was only 24 s, and deemed to short to calculate the speed with a useful level of precision.) The average speed for the second and third segments are 527 knots and 532 knots, respectively, which suggests the plane was flying close to Mmo=0.87. For instance, with a tailwind of 12 knots and a temperature offset of ISA+10.3K, a groundspeed of 527 knots converts to M0.87. At the Mmo/Vmo crossover altitude of 30,500 ft, a groundspeed of 532 knots converts to M0.86. This suggests that after the aircraft flew past Kota Bharu, it was at the upper end of its operating speed range, and possibly at times beyond it.

Calculated groundspeed as derived from the civilian radar data. (Click to enlarge.)

I know that independent investigators that contribute here and elsewhere will continue to analyze the data to better understand how MH370 was flown before it completely disappeared from all radar sites.

Update on April 12, 2018: The plot of groundspeed was updated by removing the trend lines and replacing them with average speeds over segments. In light of the noise on the speed calculations, this is more appropriate. The estimated peak groundspeed reduced from 545 knots to 532 knots. The corresponding text in (5) was also updated to reflect this change.

Update 2 on April 12, 2018: Here is an Excel file for those wishing to see the basis for my calculations. Please let me know if corrections are required.

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MH370 Search Update – Mar 18, 2018

Ocean Infinity’s search progress, from Richard Cole.

Recent Activity

Seabed Constructor, the vessel operated by Ocean Infinity to scan the seabed in search of MH370, is returning to port in Fremantle, Western Australia, to refuel, change crews, and resupply. Constructor is completing the second of three or four swings, each swing lasting about six weeks. So far, there have been no promising sonar “contacts” that might represent the debris field of the missing aircraft.

There remains about 3,000 sq km of seabed to search in the area that the ATSB and CSIRO designated as a priority. After that, the extended search area along the 7th arc would require scanning about 46,600 sq km to reach north to around 29S latitude if the width of the search was 25 NM on either side of the 7th arc. That will require more than one additional swing to complete. In fact, it could prove challenging to complete with even two additional swings, depending on the weather and how well the eight autonomous underwater vehicles (AUVs) perform. Although not publicly stated, there are indications are that at least one of the AUVs is having technical problems.

What We Know So Far

Any scenario that leads to a particular location (a “warm spot”) is based on a set of assumptions, and the failure to find the debris field in proximity to this location means that one or more of those assumptions are false. So we can be fairly certain that the large, blurry objects seen in the French satellite images were not from MH370, as the corresponding impact locations calculated by CSIRO were searched without success. Also searched was the warm spot that was calculated by assuming that the aircraft flew until fuel exhaustion on a path towards the South Pole. Unless an interesting contact was found but not yet disclosed, this scenario also can be dismissed.

In the coming weeks, other scenarios will be searched, including the impact site near 30S latitude that is based on two floating debris fields that were spotted during the aerial surveillance, and discussed at length in a previous post.

Reasons Why the Debris Field Has Not Yet Been Found

Although the area already scanned by Seabed Constructor was designated the highest probability by the ATSB and CSIRO, there are reasons why endpoints outside of this area are still possible.

  • A descent at 18:40 followed by a holding pattern, excursion, or other “loiter” before the turn to the south could mean the plane impacted along the 7th arc to the north of the priority area that has been searched. The last radar target was captured at 18:22, and after 18:28, the next ping arc derived from the BTO data is known at 19:41. There is simply no way to be sure of the path of the plane during this interval.
  • A shift in oscillator frequency of the satellite data unit (SDU) of the SATCOM, which would change the value of the fixed frequency bias (FFB) that is used to convert the location and speed data into a BFO that can be compared with the measured BFO values. In a nutshell, if the FFB shifted by +7 Hz after the power up at 18:25, endpoints as far north as 27S are allowed by the BTO and BFO data. It turns out there is an effect called “retrace” that causes oscillators that are powered down, cooled, and powered up to shift in frequency, and there are indications that a retrace shift of about -4 Hz occurred while 9M-MRO was on the ground at KLIA before the MH370 flight. A similar shift, but in the opposite direction (up) might have occurred due to the inflight power cycling.
  • Pilot inputs after 19:41 might have altered the path. The continuous, smooth progression of the BTO and BFO data suggests automated flight with few or no pilot inputs until fuel exhaustion. However, there is a remote possibility that the smooth progression of values was produced by a more complicated path that by chance replicated the simplest of paths.
  • There is also the possibility that the previous search was as the correct latitude along the 7th arc, but the width of +/- 25 NM from the 7th arc was not sufficient. The final two BFO values indicate a steep, increasing descent that if continued would mean the plane impacted close to the 7th arc. The debris is also consistent with a high-energy impact. However, it is possible, albeit unlikely, that a skilled pilot carefully recovered from the high-speed descent, regained altitude, and glided for some distance beyond 25 NM.
  • Although some of the area north of the priority search area was searched by aerial surveillance in the weeks following the disappearance, the search area was large and the coverage was spread thin. Also, some debris was seen from air, but never recovered due to the distance of ships supporting the search effort.

Simulation of Seabed Constructor’s Search Pattern

Finally, Richard Cole, who has carefully been tracking and analyzing the search patterns of Seabed Constructor, has produced a short video which shows the path of the vessel and how it relates to the launch and recovery of the AUVs. Richard is quite talented at extracting a lot of information from small amounts of data, and this video, like all his work, is commendable.

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MH370 Search Update – Feb 16, 2018

Status of current underwater search. (Click on image to enlarge.)

Recent Activity

After a short stop in Fremantle for to re-fuel, re-supply, and change crew, Seabed Constructor, operated by Ocean Infinity, is back searching for the wreckage of MH370. Ocean Infinity is under contract with Malaysia to use its team of eight autonomous underwater vehicles (AUVs) to scan the seabed in the Southern Indian Ocean (SIO) in search of wreckage from the aircraft. Under the terms of the contract, Ocean Infinity will only be paid if the wreckage is found. The search is occurring in multiple six-week long “swings”, of which the first swing has been completed, and the second swing is just beginning. Subsequent swings will also require a stop in Fremantle for servicing.

For the first swing, Ocean Infinity began by searching the 25,000 sq km of seabed that ATSB and CSIRO have designated as the priority area (shown in white in the figure). So far, Constructor has scanned about 7,500 sq km of seabed, including 5,000 sq km within the priority area that was designated by CSIRO as the “primary area” (solid white). There remains about 20,000 sq km of the priority area that is unscanned (translucent white). Beyond that is the extended search area, which reaches to about 29S latitude along the 7th arc (translucent green), and is expected to be searched at a width of +/- 25 NM from the 7th arc. Under ideal conditions, the eight AUVs are capable of scanning about 1,200 sq km of seabed each day. Recognizing the possibility of weather and operational constraints,  a more realistic expectation might be about 25,000 sq km per swing. However, until Ocean Infinity gains more operational experience, it is difficult to predict what scan rates are realistically achievable.

With the sparse and imprecise evidence we have, it is impossible to assign a high level of certainty to any impact site, as the satellite data and the drift models allow a broad range of possibilities. So, it becomes a numbers game–the more area searched, the higher probability of finding the wreckage. However, within that broad range, there are some “warm spots” that are based on assumptions about navigation inputs and other evidence.

What We Know So Far

In the previous post, I estimated the probability of finding the wreckage as 67%, assuming all of the priority and extended areas are scanned. (This probability will vary some depending on how far north the search reaches.) Considering that only 5,000 sq km of that area were scanned in the first swing, and assuming that there are equal probabilities within that total area, the probability of finding the debris field within the primary area would be about 4.4%. Considering this low percentage, it should come as no surprise that the wreckage has not yet been found, and we are far from the point of re-thinking the search strategy.

Within the area searched so far, there are three warm spots that CSIRO has designated as priorities, based on satellite images of objects that could have been MH370 debris, and from drift models that estimated the points of impact from the location of these objects. Last August, the highest priority location (CSIRO Priority 1) was described by CSIRO’s David Griffin in these words: We think it is possible to identify a most likely location of the aircraft, with unprecedented precision and certainty. Unfortunately, all three of these locations have now been scanned with negative results. Unless positive news is being withheld, the confidence expressed by CSIRO was unfounded. This is not a total surprise: The objects captured by the satellite images had too much surface area to likely be from MH370, and the location of the potential impact sites were  not consistent with the high speed descent suggested by the final BFO values.

Two other warm spots have been at least partially searched in the first swing. The first is an impact location near 34.7S latitude that Inmarsat derived by minimizing the BFO error. More recently, Bobby Ulich proposed a location near 34.8S latitude that was based on a path of constant true heading (CTH). We should know soon whether or not these warm spots are completely eliminated.

Another warm spot that should be searched during the current swing is based on a great circle path between waypoints BEDAX and the South Pole. I first proposed this path in August 2014, and I still consider it to be among the best possibilities because of the excellent fit of the BTO and BFO data, and because of the simplicity of navigating in the direction of true south. That said, despite the attractiveness of this scenario, we don’t know whether the aircraft was navigated in this manner, so it remains one of many other possibilities.

As shown in the figure above, there are warm spots that reach as far north as 27S latitude that are based on certain navigational inputs. Although the match to the BFO data is not as good for paths ending that far north, the BFO error is still well within what was recorded for previous flights of the 9M-MRO airframe. The drift models also favor an impact point further south than 27S. However, for debris discovered on the beaches of Eastern Africa, there could have been a considerable delay between the time of discovery and the time of arrival near the shore, and this uncertainty reduces the accuracy of the drift models.

In a nutshell, although the previous search swing has eliminated some possibilities, we are still very early in the search process, and it is much too early to draw any conclusions.

Unknown Activities of Seabed Constructor

The figure below from Richard Cole shows the recent behavior of Seabed Constructor. At the end of the last swing, Constructor returned to the outer leg of the primary search area, which had been previously scanned. After following the pattern of a 5-km circle, it retraced what we believe was part of a previous path of an AUV, and then disabled its AIS data, which made it impossible to remotely track. When the AIS was eventually re-enabled three days later, Constructor had left the search area, and was traveling back to Fremantle. What activities occurred during these three days is not known.

Seabed Constructor’s path, as adapted from the work of Richard Cole. (Click on image to enlarge.)

At the start of the search for the current swing, Constructor again returned to the southern end of the outer leg of the primary search area, and seems to be actively searching the seabed in this location. The activities in the current area are likely related to activities that occurred when the AIS was disabled during the last swing.

Some possibilities that have been proposed by others to explain the behavior are:

  • Constructor is re-scanning areas that had poor quality or missing data either because of malfunctioning equipment or challenging terrain
  • There are one or more promising points of interest that are under being comprehensively investigated
  • A search is underway to locate equipment that was lost in the previous swing
  • Some combination of the previous possibilities

Whatever the reason for the unexplained behavior, it is noteworthy that there was no reference to the behavior in either of the last two weekly updates from Malaysia. As Malaysia has two observers on Seabed Constructor, Malaysia is certainly aware of the surrounding circumstances. Malaysia’s decision to omit pertinent information in the weekly reports further erodes the public’s confidence in the Malaysian-led investigation. Credibility is not possible without transparency.

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