Posts Tagged ‘subsea’

Vessel Details for the 2025 Search for MH370

by Victor Iannello Posted: Tuesday, 1/28/2025

Content researched and created by Don Thompson

Armada 78-06. Credit: Wei-Lin Chen, @taiwanshipswatchers

Ocean Infinity previously conducted a search for MH370 in 2018 using a fleet of Kongsberg Hugin 6000 Autonomous Underwater Vehicles (Hugin AUVs). The AUVs were operated from Seabed Constructor, a vessel designed to support subsea construction activity. Seabed Constructor’s roster of equipment was impressive, a truly multi-purpose subsea vessel: eight Hugin AUVs, acoustic comms and positioning system, two 5000-6000m depth rated (tethered) ROVs, autonomous surface vessels, and a crane able to lift from 3000m deep.

In early 2021 Seabed Constructor’s lease was terminated, along with Normand Frontier, as Ocean Infinity prepared to introduce its fleet of Armada 78 vessels.

The Armada 78 vessels, at 78m length, are smaller than Seabed Constructor. The fleet comprises four distinct operating configurations, none of which involve permanent AUV mobilisation.  However, in the context of an MH370 search mission, an Armada 78 can operate Hugin AUVs deployed in a self-contained ISO 668 form factor hangar/garage.

Container module for deploying Hugin AUVs. Image credit: H Henriksen

As of mid-January 2025, four Armada 78 vessels are operating in European waters, one has been operating out of San Diego, California, while three underwent further completions work in Singapore following the experience of those vessels operated in Europe.

While not permanently mobilised to operate AUVs, some Armada 78 vessels have been configured to deploy AUVs: Armada 78-07, from San Diego, to the Clarion-Clipperton Zone, Pacific Ocean; Armada 78-05, surveying pipeline/connector routes in the North Sea and Norwegian Sea; and, Armada 78-06, to the Ryukyu Trench, east of Taiwan, operating out of Kaohsiung port.

Recently, through December 2024-January 2025, much discussion has ensued, speculating on which of the three vessels based in Singapore may be a candidate to conduct a renewed search for MH370 in 2025. One commentator even asserted that Armada 78-08 had been designated as the vessel to conduct the search. Through December 2024 and January 2025 Armada 78-04, 78-06, and 78-08 separately departed Singapore.

Armada 78-04 departed 14th December 2024 fully configured for geotechnical operations with its CPT and vibrocore machines in place and without AUVs. In this configuration, it was not a candidate to conduct the search. After departure from Singapore, Armada 78-04 passed through the Sunda Straits, crossed the Indian Ocean and proceeded to the Atlantic with enroute replenishment and bunkering stops at Port Louis, Mauritius, and Cape Town, South Africa.

Armada 78-06 departed for a task in deep waters east of Taiwan. At departure, it was mobilised with two containerised AUV garages on the aft deck. Upon its return to Singapore, the vessel moored at the ST Engineering facility before departing again on January 19, 2025, and broadcasting Mauritius as its destination. Armada 78-06 passed through the Sunda Straits before establishing a course across the Indian Ocean for Mauritius.

Armada 78-08 had departed for Cape Town with a replenishment and bunkering stop at Port Louis, Mauritius. The vessel is mobilised to operate two Saab Seaeye Leopard ROVs using a LARS over the forward moonpool. These ROVs do not have the ability to operate at the depths found in the MH370 search area. No containerised AUV garages were deployed on the vessel at departure from Singapore.

Following a brief stop in Cape Town, Armada 78-08 departed, this time eastbound to the small port of Mossel Bay where a containerised AUV garage was waiting on the quayside to be loaded onto the vessel. The curious folk of Mossel Bay recorded, on social media, the missing piece of the puzzle to complete the picture of vessel preparation for the MH370 search: Armada 78-08 is ferrying a third AUV to Port Louis where it will be transferred to Armada 78-06 and transit will begin to the search area.

We suspect that delivery of the third container AUV garage was delayed in transshipment to A78-08 at Cape Town. By repositioning Armada 78-08 to Mossel Bay while the intermodal container was delivered by road to the port, any overall delay to the schedule was minimised. Armada 78-08 and 78-06 should arrive at Port Louis within a short time of each other.

While the period required to fully mobilise the additional, third, containerised AUV garage on Armada 78-06 is unknown to us, an estimation of sailing time Mauritius to 7th arc search area is approximately 10 days. Assuming a rendezvous of Armada 78-06 and Armada 78-08 around February 5, and assuming a week to outfit and resupply Armada 78-06, the search might begin around February 22, and perhaps sooner if the time to outfit and re-supply Armada 78-06 occurs faster than one week.

[VI comment: Here are some additional remarks to refute claims that are circulating.]

First, there is no evidence that Malaysia will not sign a contract with OI to search again. Yes, the negotiations seem to be taking longer than any of us would like, and yes, this might reduce the duration of the search compared to the last search, but considering only 15,000 km2 of area is proposed, the shorter duration of the search might not matter. The claim that Malaysia is not interested in searching again is at best premature, and most likely it is false.

Second, there is much speculation about the trajectory of Armada 78-08, which some believe is the vessel designated for the search. More likely, that is not the selected vessel for the search. As Don deduces in the article above, Armada 78-06 is more suitably designed and outfitted for the search.

Thirdly, there is no reason to believe that the search area will be very much different than what OI proposed in March of last year (2024), as shown at the top of the prior post. That area is largely consistent with the Zone 2 search recommendation proposed in Ulich and Iannello (2023). We also hope that OI will have the willingness and capability to search the steep slope at around 33 km (18 NM) due south of our best estimate of where MH370 crossed the 7th arc. This area, centered around S34.53° E93.84°, was not previously searched by either the ATSB or OI, and remains a high priority despite the challenging terrain, as discussed in this previous post.

So, although there are still many unknowns regarding the search, including the precise start date, I still believe it is likely that a search contract will be signed and the search will proceed without many surprises.

Tags: , , , ,
Posted in Aviation | 2 Comments »

Man-Made Objects Detected on Seabed Are Possibly from MH370 – Updated

by Victor Iannello Posted: Thursday, 11/2/2023
A shipwreck found during the subsea search for MH370

The total subsea search for MH370 comprised more than 240,000 km2 of seabed in the Southern Indian Ocean (SIO) along the 7th arc, which is derived from the metadata from the last transmission from MH370’s SATCOM terminal. The search of the first 120,000 km2 was managed by the Australian Transport and Safety Bureau (ATSB), and included the areas that Australia’s Defense Science and Technology Group (DSTG) deemed most likely as the Point of Impact (POI). The ATSB’s subsea search along the 7th arc extended in latitude from 39.4 S to 32.8 S, varying in width from 130 km at the southern end of the search area to 40 km at the northern end.

An additional 120,000 square kilometers of seabed was scanned by Ocean Infinity (OI) using a fleet of autonomous underwater vehicles (AUVs). OI extended the length and width of the ATSB’s search so that a full 110 km width was scanned along the 7th arc north to a latitude 31.5 S. The search area was then narrowed to a width of 84 km and extended north along the 7th arc to a latitude of 24.8 S.

Despite this unprecedented large search in the area deemed most likely to find the debris field, the search was unsuccessful. So why wasn’t MH370’s debris field identified? There are only three realistic possibilities:

  1. The aircraft was manually piloted after fuel exhaustion and glided beyond the area that was previous searched. Although the final BFO values suggest an increasingly high rate of descent that would certainly have resulted in an impact within kilometers of the 7th arc if there had been no further pilot inputs, there is a possibility that the pilot arrested the steep descent and transitioned into a long, efficient glide.
  2. The point of impact (POI) occurred along the 7th arc further south than 39.4 S or further north than 24.8 S. For instance, although the statistical match to the satellite and drift model data is not as strong, Ed Anderson has discovered an acoustical event along the 7th arc at 8.4 S that he believes is related to MH370. Meanwhile, Paul Smithson believes an impact further south than 39.4 S is within the uncertainty limits of the fuel consumption and drift models, and should not be excluded.
  3. The debris field lies on the seabed within the area already searched, but was not identified due to challenging terrain, low quality data, or equipment issues.

Here we address the third possibility. In particular, we again consider whether the debris field might be located in the high probability search area previously identified, which is in proximity of the last estimated position (LEP) calculated in the UGIB 2020 study. We further consider whether parts of MH370 were detected but were never fully investigated because they were not part of a larger debris field.

In the figure below, the two inner yellow lines show the approximate limits of the area searched by the vessel GO Phoenix (under contract with the ATSB), and the outer lines show the limits of the Ocean Infinity search area. Also shown in the figure are olive-green areas which represent areas that were not scanned by GO Phoenix’s towfish due to steep terrain. The outlines of these and other areas of missing or low-quality data were made available by Geoscience Australia.

There is a steep slope to the south of the LEP, and the portion of the steep slope that was not scanned by the GO Phoenix towfish is about 60.3 km2. Of this, about half was later scanned by Ocean Infinity AUVs, leaving about 30.5 km2 of seabed surrounding S34.53° E93.84° that was never scanned. We designated this area as a “High Priority Search Area”, and it may be here that the debris field lies.

The subsea search for aircraft wreckage that many deem most similar to the search for MH370 was the search for Air France 447 (AF447), which was an Airbus A330 that crashed off the coast of Brazil in June 2009 in around 3000 m (9,800 ft) of water. Floating remnants of the aircraft were found within 2 days of the crash, but the subsea search was not successful in locating the debris field until April 2011, about 2 years after the crash. The sonar image from the debris field, which measured around 200 m x 600 m, is shown below.

AF447 is believed to have impacted the ocean surface without breaking up in flight and with a nose-up attitude. As such, the debris field that AF447 generated may be significantly different from the debris field created by the impact of MH370, as the final two BFO values suggest a high downward acceleration of 0.7g, and descent rates greater than 15,000 fpm. Without pilot intervention, MH370 possibly entered the water at a descent angle greater than 45 deg and at an airspeed approaching or exceeding Mach 1.

The debris from MH370 may more closely resemble the debris from SilkAir 185 rather than the debris from AF447. SilkAir 185 was a Boeing 737 that crashed into the Musi River near Palembang, Sumatra, Indonesia in December 1997. The aircraft experienced a rapid, nearly vertical dive that the US NTSB attributed to control inputs from the captain. During the high speed descent, parts of the control surfaces, including a large portion of the tail section, separated from the fuselage due to the high aerodynamic forces from the high speeds. The airspeed of the fuselage before impact is believed to have exceeded Mach 1.

SilkAir 185’s debris was found in two areas: the main debris field of around 60 m x 80 m at the bottom of the Musi River, which was only 8 m (26 ft) deep; and other larger debris, mainly flight control parts that separated before impact, that were widely scattered on land no closer than 700 m (2,300 ft) from the main debris field. According to the accident report, due to the high energy of the impact, the parts recovered from the river were “highly fragmented and mangled on impact” which made identification difficult.

If MH370 experienced the rapid descent suggested by the final BFO values, then it is probable that the fuselage broke apart before impact, and also probable that many large parts would be found outside of the main debris field. The flaperon recovered on Reunion Island is a good example of a flight control part that may have separated before impact. We would also expect the main debris field to be smaller in extent than for AF447, and within that debris field, the debris to be smaller and more difficult to identify. For instance, for the case of SilkAir 185, the landing gear was identified only by its subcomponents (struts, landing gear door actuators, wheels, brakes, tire pieces, etc.). This counters conventional wisdom that says that aircraft engines and landing gear should be among the easiest parts to identify by sonar on the seafloor, as it was the case for AF447.

The subsea search for MH370 was focused on finding the main debris field at the expense of identifying other parts that may have separated. For the search phase conducted by GO Phoenix, reports were written for a total of 45 “contacts” (observable features in images) that merited a further review. All the contact reports are compiled here. Of these 45 contacts, 24 contacts were within 100 km of the LEP, 10 contacts were within 50 km of the LEP, and 4 contacts were less than 25 km from the LEP. The locations of the contacts are shown in the figure below.

Of the 45 contacts, 11 (GP-002, 016, 018, 019, 021, 025, 026, 028, 030, 031, 047) were described in the reports with phrases like possibly “man-made”, “not geological”, or “not of natural origin”, and one (GP-046) was considered for further investigation with an AUV, which seems to have never been done. Of course, many of the man-made objects on the seafloor could be marine debris from sea vessels unrelated to MH370.

Andy Sherrill is an experienced ocean engineer who has conducted deep water search and salvage operations for a number of missions. He was a key member of the team that reviewed the sonar data for the subsea searches for MH370 that were conducted by the ATSB and Ocean Infinity. Andy was also part of team that identified the debris field for AF447 off the coast of Brazil as well as part of the team that found Argentina’s ARA San Juan submarine. Andy graciously offered these comments as to why many of the MH370 promising contacts were never investigated further:

“Typically, if there were small isolated objects that appeared to be man-made and marked as a target, but nothing else was of interest within several kilometers then we did not investigate further.

We certainly took into account if the debris field did not look like AF447 or any others, however there still needed to be enough debris to be at least a fair amount of the aircraft to warrant further investigation.

Sure a small part of the plane could have drifted and sunk, but we were looking for the main field. A decision was made to focus on finding the main field of debris, not just one small piece – and likely all of those “potentially man made” contacts are from passing vessels given there was no associated debris within several kms.

Having said that, there is always a chance it [a tagged contact] could be from MH370, but based on our assessment the time it took to investigate each of these small contacts was not worth taking vs searching new areas.”

Discussion

As the final BFO values, the lack of IFE log-on, and the end-of-flight simulations all suggest a high speed impact close to the 7th arc, a high priority should be to completely scan the areas closest to the 7th arc. MH370’s debris field may be smaller in area, consist of smaller parts, and be much more difficult to identify than searchers were anticipating. It’s also possible that the debris field is located in an area that was not fully searched due to challenging terrain, low quality data, or equipment issues, such as the steep slope identified above as the high priority search area due south of the LEP. As such, the investigation of many of the contacts previously identified becomes more important, as one or more of these contacts could be parts of MH370 that separated before impact. It’s also possible that one or more contacts are part of a less conspicuous debris field.

We again acknowledge that with pilot inputs, it is possible that MH370 glided after fuel exhaustion beyond the areas that were previously scanned. Therefore, searching wider along the 7th arc should also be part of the search plan if pursuing areas close to the 7th arc is unsuccessful in locating any of MH370’s wreckage.

Update on Nov 3, 2023

Andy Sherrill offered these additional comments:

“We did get rerun over GP16, and collected some higher frequency AUV SSS on that one. Looks highly likely to be geologic in my opinion.

We did not reacquire any more data over GP46, however that one looks very similar to GP16 and I would still classify it as highly likely to be geologic.”

Tags: , , , , ,
Posted in Aviation | 425 Comments »