The Search for MH370:
Challenges in Performing an Underwater Search in a
Remote Area of the Deep Ocean
Lead Author:
David Millar
President
Fugro Pelagos, Inc.
3574 Ruffin Road
San Diego, CA 92123
USA
[email protected]
+1 858 427 2005
Secondary Authors:
Steve Duffield
Managing Director
Fugro Survey Pty Ltd
24 Geddes Street, Balcatta
Western Australia 6021
[email protected]
+61 8 6477 4401
Paul Kennedy
Operations Manager
Fugro Survey Pty Ltd
24 Geddes Street, Balcatta
Western Australia 6021
[email protected]
+61 8 6477 4401
Abstract:
When it was decided that the Australia Transport Safety Bureau (ATSB) would lead the search
for MH370, they assumed responsibility for one of the most complex and challenging ocean
mapping and seafloor search operations ever conducted. Technical analysis of the limited
satellite communications data and aircraft flight information related to MH370 resulted in the
establishment of a prioritized search area on the seventh arc in a remote portion of the southern
Indian Ocean. Because the seafloor in this search area had never been mapped in detail
previously, before a high-resolution seafloor search could commence, it was necessary to
conduct a bathymetric survey to ensure that the seafloor search equipment could be operated
safely.
Fugro was contracted by the ATSB to perform both the initial bathymetric survey and the
subsequent seafloor search within the prioritized search area. This paper will examine the
challenges in performing an underwater search in a remote area of the deep ocean during the
Southern Hemisphere winter. It will focus primarily on the initial ocean mapping operation,
where significant differences from the previously accepted and published depths were observed,
but will also show how the results are being used in the subsequent seafloor search.
Lead Author Biography:
David Millar is the President and Managing Director of Fugro Pelagos, Inc., which is a coastal
and ocean mapping company, located in San Diego, California. He has worked there for over 23
years and has held the Chief Executive position for the past 5 years.
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The Search for MH370:
Challenges in Performing an Underwater Search in a
Remote Area of the Deep Ocean
David Millar – Fugro Pelagos, Inc. – San Diego, USA
Steve Duffield, Paul Kennedy – Fugro Survey Pty Ltd – Perth, Australia
Abstract
When it was decided that the Australia Transport Safety Bureau (ATSB) would lead the search
for MH370, they assumed responsibility for one of the most complex and challenging ocean
mapping and seafloor search operations ever conducted. Technical analysis of the limited
satellite communications data and aircraft flight information related to MH370 resulted in the
establishment of a prioritized search area on the seventh arc in a remote portion of the
southern Indian Ocean. Because the seafloor in this search area had never been mapped in
detail previously, before a high-resolution seafloor search could commence, it was necessary
to conduct a bathymetric survey to ensure that the seafloor search equipment could be
operated safely.
Fugro was contracted by the ATSB to perform both the initial bathymetric survey and the
subsequent seafloor search within the prioritized search area. This paper will examine the
challenges in performing an underwater search in a remote area of the deep ocean during the
Southern Hemisphere winter. It will focus primarily on the initial ocean mapping operation,
where significant differences from the previously accepted and published depths were
observed, but will also show how the results are being used in the subsequent seafloor search.
1.0 Introduction
On 8 March 2014, Malaysia Airlines Flight 370 (MH370), a Boeing 777-200ER with 239
passengers and crew onboard, disappeared from air traffic control radar during a regularly
scheduled flight from Kuala Lumpur, Malaysia to Beijing, China. Initial search efforts were
focused in the Gulf of Thailand and Southern China Sea, where the aircraft lost contact with air
traffic control during a transition from Malaysian and Vietnamese airspace. These efforts were
soon expanded to include the Strait of Malacca and the Andaman Sea, when it was realized that
Malaysia military radar continued to track the aircraft over the Malay Peninsula into the
Andaman Sea, after it had deviated from its planned flight path. Subsequent analysis of radar and
satellite communication data indicated that the aircraft remained in flight for 6 hours after the
final military radar fix and placed the aircraft on an arc in the Southern Indian Ocean, within the
Australian search and rescue zone. The subsequent search that occurred and which continues
today has been the most complicated and expensive search operation in history.
On 17 March 2014, the Australian government took charge of the coordination of the search and
rescue operation and on 18 March 2014, a massive multinational aerial and surface search
commenced, involving assets from Australia, Malaysia, China, Japan, Korea, UK and the USA.
Based on information from a Joint Investigation Team (JIT) in Malaysia and other government
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and academic sources, The Australian Maritime Safety Authority (AMSA) and the Australia
Transportation Safety Bureau (ATSB) jointly determined a search area strategy and over the next
six weeks, the surface search covered over 4,600,000 km2 and involved 19 vessels and 345
aircraft sorties. The aerial search concluded on 28 April 2014 without any aircraft debris found
and search then moved to an underwater phase. An ocean floor search in the vicinity of acoustic
detections (thought to be from underwater locator beacon) continued through 28 May 2014.
Figure 1 shows the planned route, the initial radar track, the arc on which satellite
communications indicated the aircraft to be, the location of acoustic detections, the initial surface
search areas and the initial (26 June) priority seafloor search area.
At the same time, the ATSB coordinated a search strategy group comprised of international
satellite and aircraft specialists to further define the most probable position of the aircraft at the
time of the last satellite communications. By using aircraft performance data and data from a
communications satellite system, the group estimated the track of the aircraft and the ATSB
determined a priority 60,000 km2 search area.
Figure 1: The initial surface search locations and information that established it (Source:
Malaysian Government and Australian Maritime Safety Authority)
Because this priority search area was located in an extremely remote and poorly mapped region
of the Southern Indian Ocean, before any high-resolution deep-water search could commence, it
was first necessary to conduct a bathymetric survey of the ocean floor to ensure that the seafloor
search equipment could be operated safely. This operation commenced in mid-May 2014, when
Fugro was contracted by the ATSB and the Fugro Equator joined a Chinese military vessel in
mapping the ocean floor within the wide search area. In early June 2014, the ATSB issued a
Request for Tender (RFT) for the subsequent deep-water search and in August 2014, Fugro was
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also awarded a contract for the high-resolution deep-water search operation as well.
This paper will look at the challenges in performing an underwater search in a remote and poorly
mapped area of the deep ocean and show how the initial ocean mapping data area being used in
the subsequent seafloor search. Because Fugro is not responsible for defining the search area, the
paper will not dwell on that aspect of the search, though some contextual background will be
provided.
2.0 Establishing the Search Area
One of the biggest challenges in the search for MH370 has been establishing where to search.
Unlike most over-water accidents, where reverse-drift techniques are used to determine the
aircraft impact location from floating wreckage, after almost one-year, not a single piece of
aircraft wreckage has been found. In addition, underwater locator beacons fitted to the flight
recorders can also be used to determine the location of wreckage on the seabed. They have a
limited operational endurance, however, (nominally 30-days) and despite some false positives
back in the early days of the search, no emergency locator transmissions were ever detected.
Furthermore, the following circumstances make the disappearance of MH370 a mystery and
have further complicated the establishment of a reasonable search area:
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The final automatically transmitted position occurred 66 minutes into the flight
The last radio communications from the crew was received 78 minutes into the flight
There was no radio notification of a problem received from the crew
The final ATC (secondary) radar fix occurred 81 minutes into the flight
The aircraft deviated from its planned flight path 84 minutes into the flight
The final military (primary) radar fix occurred 181 minutes into the flight
The satellite communications log indicated the aircraft continued to fly another 6 hours
No confirmed eye-witness reports were received
As a result, the search area for MH370 remains very large and has largely been defined through
an analysis of the flight and satellite data as well as performance data of the aircraft.
The priority search area that resulted in June 2014 was approximately 60,000 km2 and extended
in an arc 650 km in length and 93 km in width. Further analysis of the communications data has
result in changes in the prioritization and locale of search activity and in fact, the latest models
have moved the priority search area further south on the 7th arc. Figure 2 shows the initial search
area map that was produced by the ATSB in June 2014, while Figure 3 shows an analysis of the
satellite communications data that lead to the establishment of the initial priority search area in
June 2014.
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Figure 2: MH370 Search Area Map 24 June 2014
(Source: Australia Transportation Safety Bureau and Geoscience Australia)
Figure 3: Results from Satellite Communications Analysis where white paths represent the
highest correlation with satellite data
(Source: Australia Transportation Safety Bureau and Satellite Working Group)
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3.0 Developing the Search Plan
With the priority search area constrained to approximately 60,000 km2 of the Southern Indian
Ocean, the next big challenge was execute a high-resolution deep ocean search. This could not
commence until a bathymetric survey of the search area was conducted, however, to ensure that
the seafloor search equipment could be operated safely. Like most of the world’s oceans, this part
of the Southern Indian Ocean has not been accurately mapped and existing maps of the seafloor
within the search area were very coarse.
The topography of the ocean floor within the priority search area had been derived from a
combination of satellite altimetry and ocean passage soundings. The prior provides full seabed
coverage, but at a very low resolution and with relatively low accuracy. The latter provides
higher resolution data at a higher accuracy, but only in relatively spares and isolated areas. As
result, existing seafloor maps within the priority search area provided only a general indication
of water depth and were insufficient to conduct a high-resolution deep ocean search.
Satellite altimetry estimates water depth by accurate and repeated radar measurements of the sea
surface. Depth estimates from satellite altimetry are most accurate where the ocean floor
topography is moderate and composed of ocean crust overlain by less than 200 m of sediment.
The resolution of bathymetry derived from satellite altimetry is very coarse, however, and can be
on the order of 3,400 m.
Consequently, the first step in searching for the wreckage of MH370 within the priority search
area was to conduct a bathymetric survey. To this end, the ATSB awarded a contract to Fugro in
June 2014 to conduct a bathymetric survey of priority search area. This work was executed by
the Fugro Equator in collaboration with the Chinese survey vessel Zhu Khezhen. At the same
time, the ATSB issued a Request for Tender for the subsequent deep-water search operation and
in August 2014, Fugro was also awarded a contract for the high-resolution deep-water search
operation as well. The data acquired during the bathymetric survey were obviously critical in
determining the equipment, processes and priorities for future activities, including the highresolution search operation. The initial bathymetric survey was not intended, nor was it capable
of detecting the wreckage of MH370, even if the aircraft were fully intact on the seabed.
4.0 Bathymetric Survey of the Priority Search Area
In early June 2014, the Fugro Equator commenced a bathymetric survey of the search area. The
vessel is a large ocean going, purpose built survey vessel that is quiet, efficient and reliable. It is
a “new build” vessel that was added to the Fugro fleet in 2012. It is equipped with a hull
mounted Kongsberg EM302 1º x 1º multibeam system, a Kongsberg SBP 300 sub-bottom
profiler system, Applanix POS MV 302 system, Starfix DGNSS positioning system and an
Inmarsat Global Express satellite communications system. The Fugro Equator is 1917 gross tons
has a length of 66 m, a beam of 14 m and a draught of 4.2 m. A photograph of the Fugro Equator
is shown in Figure 4.
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Figure 4: The purpose-built survey vessel Fugro Equator
The vessel had to transit between 1,869 km and 2,690 km to get back and forth between the
search area and re-supply base in Freemantle, Australia. The vessel would return to base
approximately once per month to re-supply and exchange crew. When on-site, conditions were
very tough, with the survey occurring in the Southern Indian Ocean during the southern
hemisphere winter. Sea conditions wave heights were typically 8 m, though up to 16 m.
Between early June and late December, approximately 200,000 km2 of seabed had been surveyed
by the Fugro Equator and Zhu Khezhen. Water depths ranged from 1,325 m to 6,250 m and the
survey revealed many seabed features for the first time. These included seamounts, ridges
approaching 300 m of relief and depressions extending 1,400m deep, as well as finer-scale
seabed features that were not visible in the previous low-resolution data that had been derived
from satellite altimetry. In general, the seabed was more complex and irregular than anticipated.
Additionally, huge variations in absolute depth were found between this high-resolution
bathymetric survey and the previous bathymetry that had been derived from satellite bathymetry.
Much of the area was within +/-100 m, however, there were areas where the differences
exceeded +1,200 m and -1,200 m.
ATSB has published some maps from bathymetric survey of the priority search area, but data
collected ultimately be released by Geoscience Australia.
Figure 5 presents a map that shows the progress of the bathymetric survey through 23 December
2014. Figure 6 shows a 3D rendering of the bathymetric survey for an area of seabed around and
to the south of Broken Ridge. Figure 7 shows the differences in water depth observed between
the bathymetric survey and the previous bathymetry data derived from satellite bathymetry.
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Figure 5: Bathymetric Survey Progress Map - Released 23 December 2014
(Source: Australia Transportation Safety Bureau and Geoscience Australia)
Figure 6: Three-Dimensional Model of the Sea Floor Terrain
(Source: Australia Transportation Safety Bureau and Geoscience Australia)
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Figure 7: Differences in Water Depth between the Bathymetric Survey and the Previous
Bathymetry Derived from Satellite Bathymetry
4.0 High-Resolution Search and Optical Imaging of the Priority Search Area
On 4 June 2014, the ATSB released a RFT to acquire the services of a specialist company
capable of conducting a deep-water search for MH370 under their direction. The successful
contractor was to provide the expertise, equipment and vessel or vessels necessary to undertake
an underwater search for the missing aircraft in a priority search area defined by the ATSB.
While the precise search zone was still being established during the tender process, it was
expected that the successful tenderer would search an area up to 60,000 km2. The successful
tender would localize, positively identify and map the debris field of MH370 using specialized
equipment such as towed and autonomous underwater vehicles with mounted sonar and/or
optical imaging systems. Data from a bathymetric survey (contracted separately and underway at
the time of the RFT) was to be provided to the successful contractor to aid in the search. The
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search vessel or vessels used by the prime contractor may also be coordinated with other vessels
undertaking search activities in the search zone on behalf of other countries.
In August 2014, Fugro was awarded the ATSB contract to conduct a deep-water search for
MH370. The Fugro proposal was based on the approach used in the successful Air France Flight
477 search. It offered multiple vessels, utilizing deep-tow sidescan sonar systems for conducting
a high-resolution, wide area search to find and identify the debris field. It was necessary to detect
2 m2 objects (size of a Rolls Royce Trent engine) in up to 6,000 m water depth, such that a debris
field could be positively identified, while not producing false negatives. Once a debris field was
found, autonomous underwater vehicles (AUVs) would be used to provide mapping and optical
imaging of the debris field to ultimately produce a photo mosaic for the aircraft engineers. This
would prioritize the recovery of specific aircraft components, including flight recorders, thereby
assisting with the Malaysian investigation.
While the Fugro Equator was still conducting the bathymetric survey of the search area, the
Fugro Discovery commenced the high-resolution deep ocean search in October 2014. Like the
Fugro Equator, the Fugro Discovery is a large ocean going survey vessel that is acoustically
quiet, efficient and reliable. It was built in 1997, but acquired and retro-fitted by Fugro in 2007
as part of its vessel modernization program. For this project, it was equipped with an EdgeTech
DT-1 deep tow mapping system that included a 75 kHz sidescan sonar, an underwater video
camera and aviation fuel detection sensors. The system would be towed approximately 150 m
above seabed which depending on the water depth could result in a tow that was up to 9 km
behind the vessel. Figure 7 shows one of Fugro’s EdgeTech DT-1 Deep Tow sidescan sonar
systems, while Figure 8 presents a rendering of the operational / tow configuration used on the
deep-water search.
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Figure 8: Fugro’s EdgeTech DT-1 Deep Tow Survey Systems
Figure 8: Rendering of the Operational/Tow Configuration Used on the Deep-Water Search
Upon completion of the bathymetric survey work in December 2014, the Fugro Equator was
mobilized to conduct underwater search operations as well and in late January 2015, it
commenced search activities in the defined search area. The Fugro Equator was equipped with
identical survey systems as were being used on the Fugro Discovery.
As a result of the extremely complex seabed in portions of the priority search area, it was
decided to mobilize a third Fugro vessel, equipped with an AUV, to the search area. The logic
being that an AUV would be able to safely and efficiently survey those portions of the search
area that could not be searched effectively by the towed systems being used on the other vessels.
By late January 2015, the Fugro Supporter commenced search operations utilizing a Kongsberg
Hugin 4500 AUV. The Hugin AUV operates autonomously and is self-propelled (not towed),
meaning it can better navigate around the most complex terrain within the priority search area.
The AUV includes a still-camera capability and was retro-fitted with the identical side scan sonar
transducers and frequencies as the deep tow systems. It has an endurance of approximately 24
hours and returns to the surface at approximately this interval to download data and power recharge.
It should be mentioned that in addition to the three Fugro vessels currently engaged in the highresolution search, a fourth vessel, the GO Phoenix, has also been participating in this phase of
the operation. The GO Phoenix is being used by Phoenix International Holdings to provide deepwater towed sidescan sonar services in the search and has been contracted by DRB-HICOM
Defence Technologies (DEFTECH), who was contracted by Petroliam Nasional Berhad
(Petronas) and the Government of Malaysia. Their operation is closely coordinated by the ATSB.
As of mid-February 2015, over 24,000 km2 of the seafloor have been searched, which represents
approximately 40 per cent of the priority search area. Barring no other significant delays with
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vessels, equipment or from the weather, the current underwater search area may be largely
completed in May 2015.
Figure 9 presents the underwater search area priorities as of 14 January 2015. When compared to
Figure 2, one can see that the underwater search priorities have moved to the southwest.
Figure 9: Underwater Search Area Priorities 14 January 2015
(Source: Australia Transportation Safety Bureau and Geoscience Australia)
Figure 10: Representation of Probability Distribution from Satellite Communications
Analysis where Red Paths are Most Probable
(Source: Australia Transportation Safety Bureau and Flight Path Reconstruction Group)
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This movement is the result of further analysis of the satellite communications data that has been
ongoing and whose latest analysis is presented in Figure 10.
When the debris field is finally found, an ultra-high resolution mapping and optical imaging
program will be conducted. This work will be performed using either a Kongsberg Hugin 4500
(Fugro Echo Surveyor VII) or a Remus 6000 AUV, depending on the water depth. The Hugin
4500 can operate up to 4,500 m water depth, while the Remus 6000 AUV can operate up to
6,000 m water depth. Both AUV systems are equipped with high-resolution MBES and highresolution cameras.
Figure 11: Fugro’s Hugin Echo Surveyor VII AUV
5.0 Final Thoughts
Almost one-year after Malaysia Airlines Flight 370 went missing, the search continues. It
remains one of the biggest aviation mysteries in history and leaves friends and families of the
239 victims with continued grief, loss and a lack of closure. Despite a lack of any physical
evidence and the extreme challenges associated with a deep-ocean search in this remote and
hostile part of the ocean, the search goes on. Already the largest and most expensive search in
aviation history, we press on, so that we can provide closure for the families of the lost and
provide information that could potentially prevent a recurrence.
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References:
Australian Government. Australian Transport Safety Bureau. Fact Sheet. Considerations on
Defining the Search Area - MH370. Australia: 26 May 2014. Web. 21 Feb. 2015.
Australian Government. Australian Transport Safety Bureau. ATSB Transport Safety Report,
External Aviation Investigation, AE-2014-054, MH370 – Definition of Underwater
Search Areas. Australia: 18 August 2014. Web. 21 Feb. 2015.
Australian Government. Australian Transport Safety Bureau. Fact Sheet. MH370: Bathymetric
Survey. Australia: 10 September 2014. Web. 21 Feb. 2015.
Australian Government. Australian Transport Safety Bureau. ATSB Transport Safety Report,
External Aviation Investigation, AE-2014-054, MH370 – Flight Path Analysis Update.
Australia: 8 October 2014. Web. 21 Feb. 2015.
Sandwell, D. and Smith, W. “Exploring the Ocean Basins with Satellite Altimeter Data.”
National Geophysical Data Center, National Oceanographic and Atmospheric
Administration, 25 November, 2004. Web. 21 Feb. 2015.
<http://www.ngdc.noaa.gov/mgg/bathymetry/predicted/explore.HTML>.
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