Frequently asked questions

The search for missing Malaysia Airlines flight MH370 comprised two phases. Phase One, a bathymetric survey, provided a detailed map of the sea floor topography in the search area; this was used to guide Phase Two, a more detailed underwater sea floor search.

Australia, with the support of Malaysia and the People's Republic of China, committed to publicly releasing the data acquired during the bathymetric survey and underwater search. The Phase One and Two data are now available in multiple formats via the Geoscience Australia website.

Phase One of the search was a first pass survey that provided detailed information on the sea floor topography, or bathymetry, of the search area using multibeam sonar equipment mounted on ships. This data was then used to plan and guide Phase Two of the search, the underwater search which collected data using towed and autonomous underwater vehicles.

The underwater search used sidescan and multibeam sonar equipment mounted on towed and autonomous underwater vehicles to collect high resolution sonar images of the sea floor in an attempt to identify the location of MH370.

Phase One data was acquired by vessels from the sea surface, while the Phase Two data was acquired by underwater vehicles towed approximately 100 metres above the sea floor. As a result the resolution of the Phase 2 data is much higher, and consequently, much larger in data volume than Phase One.

Bathymetry is the study and mapping of sea floor topography. It involves obtaining measurements of the depth of the ocean and is equivalent to mapping the topography (or the shape of the ground) on land.

Further information on bathymetry is available via the Geoscience Australia website.

Bathymetry data is collected using sonar equipment mounted on the hull of a survey vessel. The sonar system (known as a multibeam echosounder) sends out multiple soundwaves that bounce off the sea floor and return to the ship. The delay between sending and receiving the signal provides a measurement of ocean depth.

Collecting multibeam bathymetry data is a time-consuming process where the ship travels across the water in overlapping lines, similar to mowing grass. Scientists then process this data to produce a map charting the depth of the water and the terrain of the sea floor.

Further information on bathymetry is available via the Geoscience Australia website.

Phase One of the search involved the collection of backscatter data along with the bathymetry data. Backscatter data provides information on the& ‘hardness’ of the sea floor and is used to differentiate between different types of sea floor, such as hard rock or soft sediment.

Backscatter data was collected using the multibeam echosounder at the same time as the bathymetry data. While bathymetry uses sonar signals to obtain measurements of the depth of the ocean, backscatter measures the strength of the return sonar signal off the sea floor to determine the sea floor hardness.

The backscatter data provided additional information on possible navigational hazards in the search area which was important for the navigation of the Phase Two underwater vehicles.

Backscatter data was also used to identify any unusually hard areas of the sea floor to investigate further in Phase Two. The backscatter provided an indication of where hardness changed, and where further investigations should be undertaken. Phase Two of the search provided the high resolution data to identify features in much greater detail.

More information on backscatter data is available on the Geoscience Australia website.

Phase Two of the search involved the collection of sidescan sonar data, along with bathymetry and backscatter data from multibeam sonar.

Sidescan sonar data efficiently creates a detailed image of the sea floor and provides information on seabed texture and substrate types, such as hard rock or soft sediment. This data was used in the search to identify any unusual shapes or hard surfaces on the seafloor. Because sidescan sonar data can be acquired at centimetre resolution, it allowed the search to identify potential areas, or features for further investigation with an underwater camera.

During the search, sidescan sonar data was acquired by a towed-body or 'fish', typically composed of two transducers mounted on either side of the body. Sidescan sonar data uses high-frequency sound pulses that are bounced off the seafloor and received by the transducers. Coverage of sidescan data is very wide, but due to the geometry of the transducers, the data is quite poor in the nadir area (directly beneath the sonar). Therefore, bathymetry and backscatter data from multibeam sonar was collected simultaneously with sidescan sonar data to infill the nadir areas during phase 2.

Geoscience Australia is the Australian Government’s expert geology and geography organisation and has extensive experience conducting marine surveys. Given its expertise in this field, Geoscience Australia provided advice and support to the Australian Transport Safety Bureau on procurement, technology and planning for the search for MH370. As the data custodian for geophysical data in the Australian territories and the MH370 search data, Geoscience Australia processed and archived the Phase One bathymetric data. Geoscience Australia is also responsible for archiving and releasing the Phase Two data.

At various stages, Geoscience Australia had 30 to 40 staff involved in the search for MH370. The search for MH370 involved staff from a range of disciplines including marine geologists, marine ecologists, marine acoustics experts, geophysicists, spatial analysts, numerical modellers, cartographers, hydrographers, project managers, data management specialists, software developers and contract specialists.

The higher resolution of the Phase Two data means that the quantity of data is exponentially larger than Phase One; this makes the public delivery of this data more resource-intensive. Also, as the types of data that were acquired during Phase Two are more complex than Phase One, it is a more time-consuming process and involves staff across a number of disciplines to quality assess, verify and restructure the data so it can be delivered to be public. As the data is also highly complex and intended for use by professionals and technical experts; accessing, processing and analysing the data will require specialised training and software.

In January 2018, the Government of Malaysia accepted the offer by Ocean Infinity to continue to search for the missing Malaysian Airlines flight MH370 for 90 days. They had focused on the search zone identified by the Australian Transport Safety Bureau, and used up to eight Autonomous Underwater Vehicles (AUV) to collect high resolution information. This information was collected using sidescan sonars, mulitbeam echoscounders, sub-bottom profilers, cameras, CTDs, SASs and turbidity sensors. This data acquisition is comparable to data previously acquired during Phase 2 . Geoscience Australia has not been involved in the search effort with Ocean Infinity.

Geoscience Australia has not been involved in the search effort with Ocean Infinity. All enquiries regarding access to the data acquired during this stage should be directed to Ocean Infinity and the Malaysian Government.

Phase One and Two data were acquired with best available technology; however, this technology can be hampered by factors such as poor weather conditions, the depth of the water and the movement of the survey vessel. While these factors make it more difficult to acquire consistent data and can result in ‘gaps’ in the data, all possible precautions were taken to ensure the processed data quality for Phase One was sufficient to safely guide navigation of the towed and remotely operated underwater sonar equipment in Phase Two of the search. In particular, the ships conducting the Phase One survey moved across the search area in overlapping lines to compensate for possible gaps in the data and to ensure there was full coverage of data.

As part of the Phase One data release, the 'transit data' is also being released. The transit data is bathymetry data that was collected as the survey vessels travelled to and from the search area, which is why it appears in lines from the search area to the coast of Western Australia and Singapore.

The transit data was collected by the contracted survey company, Fugro Survey Pty Ltd, who acquired this additional bathymetry data at no cost to the search. This data along with the bathymetry data gathered in the search area is now being released to the public.

The data collected in the search for MH370 during Phase 1 and 2 will contribute to a better understanding of the formation of the southern Indian Ocean. This data could provide new insights for scientists in particular related to:

• continental margin geology
• plate tectonic history
• seabed processes
• identifying unusual sea floor features
• the direction of future survey expeditions to investigate these features

Bathymetry data can also be used as a baseline product in the creation of hydrodynamic models to understand ocean currents, oceanographic connectivity (biological or physical) between different areas of the ocean, and short and long term trends in environmental variables, such as climate. Biological and physical connectivity (dispersal rates) can be affected by geographic barriers (land mass, spatial scale, varying seascapes and drastic environmental gradients).

The depth of the ocean is a major factor in defining the habitat for flora and fauna. Pressure, light and temperature are all reliant on the depth of the ocean, and these conditions affect the suitability of the habitat for individual organisms. Understanding the bathymetry of the sea floor may help scientists identify areas where there may be unique flora and fauna.

The world's deep oceans have had little investigation with only 10 to 15 per cent having been mapped with the sonar technology similar to that used in the search for MH370.

Previous maps of the sea floor in the search area were derived from satellite data, which only showed the depth of the ocean at low resolution. The Phase One data was used to generate maps that are at least 15 times higher resolution than previous maps of the sea floor in the search area. The spatial resolution of the seafloor increased from an average of 100km to 0.1km horizontally, and by over 20 times vertically (>100m to ~5m), with the greatest discrepancies occurring over complex features such as Broken Ridge and Diamantina Trench (up to 2,400m) (Picard et al., 2017).

Bathymetry data provides information on the geology of the sea floor and so it could be of interest to a variety of scientific and industry groups, including mining and resources companies.

The purpose of Phase One data was not to detect possible debris from the missing aircraft but to build maps to guide the navigation of the underwater vehicles for the second phase of the search.

Phase One data is at a resolution that is not high enough to identify many man-made objects, such as shipping containers, or shipwrecks.

Phase Two data is much higher resolution and can be used to identify even small man-made objects such as 44-gallon drums, shipwrecks and fishing equipment. Some imagery collected from video and camera systems installed on remotely operated vehicles or the towed-body during Phase Two of the search is available on the ATSB website. The raw and processed data from Phase Two is viewable and downloadable from Geoscience Australia's Marine Data Discovery Portal and the National Computational Infrastructure, respectively.

The search has always been based on the best information and analysis at the time. Analysis of available data has been ongoing since the search for MH370 commenced. Results assisted the initial search and rescue mission and later refinements formed the basis for all of the underwater search activities.

As more information emerged, be it through the discovery of debris from the aircraft, drift modelling of ocean currents, or ongoing analysis of satellite data, those insights were applied to the search. A dedicated team of the best experts from around the world have continued to refine a unique range of analyses to define the probable final location of the aircraft. Experiments were conducted to ensure that predictions and assumptions aligned with actual flight data.

At a meeting of Ministers from Malaysia, Australia and the People's Republic of China on 22 July 2016, it was agreed that should the aircraft not be located in the then-current search area, and in the absence of credible new evidence leading to the identification of a specific location of the aircraft, the search would be suspended upon completion of the 120,000 square kilometre search area.

From 2-4 November 2016, experts in data processing, satellite communications, accident investigation, aircraft performance, flight operations, sonar data, acoustic data and oceanography gathered in Canberra to reassess and validate existing evidence and to identify any new analysis that may assist in identifying the location of the missing aircraft. They agreed that the methodology and effectiveness of the underwater search meant that if an area had been searched there was little to no chance that any aircraft debris had been missed.

While the MH370 search area is in the Australian search and rescue zone, it is not that close to Australia. At its closest, the search area is about 1,870 kilometres from Perth. There are complex ocean currents between the search area and the coast of Australia and this lack of debris arriving on our coastline to date is one of the key pieces of evidence used by the CSIRO in their work examining the drift of debris.

The Story Map, 'The data behind the search for MH370', is designed to provide an exploration of the data acquired and to learn more about the search and interesting findings from contacts that were identified from the Phase 2 datasets. For users wanting to explore the data in greater detail, the contacts database is available for download from the National Computational Infrastructure.

The full resolution (10cm) of Phase 2 sidescan sonar datasets cannot be visualised on this application due to size limitations. However, they are available for download from the National Computational Infrastructure.

Phase One and Two* data is now available to the public via the Geoscience Australia website and the National Computational Infrastructure in a range of formats:

• To learn more about the search for MH370 and to view the data, see The data behind the search for MH370.

For technical users wanting to download the processed data:

• To further visualise and download datasets, visit marine.ga.gov.au/#/

For technical users wanting to download the raw data:

(Please note the raw data is large in terms of data volume, requires speciality software, knowledge and high capacity systems to use the data)

• To download the Phase 1 raw data visit the National Computational Infrastructure
• To download the Phase 2 raw data visit the National Computational Infrastructure
• Amazon Web Service users can access the Phase 1 raw data via s3://mh370.phase1.data.

*As the data is also highly complex and intended for use by professionals and technical experts, accessing, processing and analysing the data will require specialised training and software. Please note that the raw Phase 2 data are provided to the public in the format it was supplied to Geoscience Australia by third party organisations, no additional edits to the datasets have been made.