Investigation and Search for Malaysian MH370




On 08 March 2014, MH370, a scheduled passenger flight from Kuala Lumpur to Beijing, operated by MAS went missing soon after a routine handover from the Malaysian ATC to Viet Nam ATC. Communications with the aircraft were lost after it passed waypoint IGARI, less than 40 minutes after takeoff. The aircraft operating the flight was a Boeing 777-200ER, registered 9M-MRO. On board the aircraft were 12 crew and 227 passengers (239 persons in total).

 Evidence shows that Flight MH370 diverted from the filed flight plan route. The aircraft’s transponder signal ceased for reasons that could not be established and was then no longer visible on the ATC radar display. The changes in the aircraft flight path after the aircraft passed waypoint IGARI were captured by both civilian and military radars. These changes, evidently seen as turning slightly to the right first and then to the left and flying across the Peninsular Malaysia, followed by a right turn south of Penang Island to the north-west and a subsequent (unrecorded) turn towards the Southern Indian Ocean, are difficult to attribute to anomalous system issues alone. It could not be established whether the aircraft was flown by anyone other than the pilots. Later flight simulator trials established that the turn back was likely made while the aircraft was under manual control and not the autopilot.

 KL ATSC operation was normal with no significant observation until the handover to Viet Nam ATC. Being the accepting unit, HCM ACC did not notify the transferring unit (KL ATSC) when two-way communication was not established with MH370 within five minutes of the estimated time of the transfer of control point (Establishment of Communications, page 11 of Operational LOA between DCA Malaysia and Vietnam Air Traffic Management effective 1 November 2001). Likewise, KL ATSC should have acted to contact HCM ACC, instead, relied on position information of the aircraft provided by MAS Flight Operations. By this time, the aircraft had left the range of radars visible to the KL ATSC. It is noted that about one minute elapsed from the last transmission from MH370 and the SSR being lost from the radar display. The Air Traffic Controllers of both Centres did not initiate the various emergency phases as required then, thereby delaying the activation of the alerting and Search and Rescue operations.

The PIC and FO held valid airman licences and medical certification. There is no evidence to suggest that the PIC and FO experienced recent changes or

difficulties in personal relationships or that there were any conflicts or problems between them. All the flight and cabin crew were certified fit to fly and were within duty-time limits at the time of the flight and were adequately rested. There had been no financial stress or impending insolvency, recent or additional insurance coverage purchased or recent behavioural changes for the crew.

The radio-telephony communications conducted by the PIC and the FO with the Air Traffic Controllers conformed to the routine procedure and no evidence of anxiety or stress was detected in the communications.

 The aircraft maintenance records indicated that the aircraft was equipped and maintained in accordance with existing regulations and approved procedures, except for the instance of the SSFDR ULB battery which had expired. The aircraft had a valid Certificate of Airworthiness and was airworthy when released for the flight and there was no record or report of any defect or malfunction in the aircraft that could have contributed to the event. Although it cannot be conclusively ruled out that an aircraft or system malfunction was a cause, based on the limited evidence available, it is more likely that the loss of communications (VHF and HF communications, ACARS, SATCOM and Transponder) prior to the diversion is due to the systems being manually turned off or power interrupted to them or additionally in the case of VHF and HF, not used, whether with intent or otherwise. No ELT signal from the aircraft was reported by the Search and Rescue agencies or any other aircraft.

 The SATCOM data indicated that the aircraft was airborne for more than 7 hours suggesting that the autopilot was probably functioning, at least in the basic modes, for the aircraft to be flown for such a long duration. This in turn suggests that the air and inertial data were probably available to the autopilot system and/or the crew. The inter-dependency of operation of the various aircraft systems suggests that significant parts of the aircraft electrical power system were likely to be functioning throughout the flight. The analysis of the relevant aircraft systems considering the route followed by the aircraft and the height at which it flew, constrained by its performance and range capability, does not suggest a mechanical problem with the aircraft’s airframe, control systems, fuel or engines. Except for the first report, the ACARS reports normally sent every 30 minutes by the SATCOM system were not received. Data from the last seven SATCOM ‘handshakes’ were used to help establish the approximate path of the aircraft over the Indian Ocean.

The initial log-on request and the hourly pings have been termed as ‘handshakes’. SATCOM transmissions indicated that a link was available from 1825 UTC on 07 March 2014 to 0011 UTC on 08 March 2014 although not used for any voice, ACARS or other data services apart from two unanswered ground-to-air telephone calls.

Two log-ons, at 1825 UTC (07 March 2014) and 0019 UTC (08 March 2014), were initiated by the aircraft most likely due to power interruptions to the SATCOM avionics. The power interruption leading up to 1825 UTC was probably due to power bus cycling, the reason for it being unknown. The power interruption leading up to 0019 UTC was probably due to low fuel at this time resulting in the loss of both engines and their respective generators. There was probably enough fuel for the APU to start up and run long enough for its generator to power the SATCOM avionics to initiate a log-on request.

 To date, the main wreckage of MH370 has still not been found despite a 4-year search in the South Indian Ocean. However, items of debris possibly from MH370, have been found as far north as the eastern coast of Tanzania and far south as the eastern coast of South Africa. This is in addition to several islands and island nations off the east coast of the African continent. Of these, the flaperon, a part of the right outboard flap and a section of the left outboard flap were confirmed to be from MH370. A few other pieces of debris were determined to be almost certain from MH370 which included some cabin interior items.

Damage examination on the recovered part of the right outboard flap, together with the damage found on the right flaperon has led to the conclusion that the right outboard flap was most likely in the retracted position and the right flaperon was probably at, or close to, the neutral position at the time they separated from the wing. Recovery of the cabin interior debris suggests that the aircraft was likely to have broken up. However, there is insufficient information to determine if the aircraft broke up in the air or during impact with the ocean. Apart from the above, no other information about in-flight emergencies, aircraft configuration or impact could be inferred from the nature and damage of the debris.

 MH370 did not carry any cargo classified as dangerous goods. Two cargo items of interest (the Lithium ion Batteries and Mangosteens) which were carried on MH370 had also been transported via scheduled flights on MAS before and after the event. These items were packed and loaded according to standard operating procedures.

As a result of the identified issues, the investigation has issued safety recommendations to enhance the safety of the aviation system. The recommendations made address the Malaysian and foreign air traffic surveillance systems, cargo scanning, flight crew medical and training records, reporting and following-up of crew mental health, flight-following system, development of a Quick Reference for Operations Control and ELT effectiveness.

 It should be recognised that there is a significant lack of evidence available to the Team to determine with any certainty the reasons that the aircraft diverted from its filed flight plan route. However, the change in flight path likely resulted from manual inputs. The lack of evidence includes the exact location and disposition of the main aircraft wreckage and the evidence that it could provide, the information recorded on the Flight Data Recorder, Cockpit Voice Recorder and other recording devices on the aircraft and the absence of any aircraft voice or data transmissions that could indicate why the aircraft flew to the Southern Indian Ocean. Without the benefit of the examination of the aircraft wreckage and recorded flight data information, the investigation was unable to identify any plausible aircraft or systems failure mode that would lead to the observed systems deactivation, diversion from the filed flight plan route and the subsequent flight path taken by the aircraft. However, the same lack of evidence precluded the investigation from definitely eliminating that possibility. The possibility of intervention by a third party cannot be excluded either.

 The disappearance of MH370 and the search effort are unprecedented in commercial aviation history. Improvements must be undertaken to ensure that this type of event is identified as soon as possible, and mechanisms are in place to track an aircraft that is not following its filed flight plan for any reason.

 In recent years, several States have expended significant amounts of funds and resources searching for missing commercial aircraft in remote oceanic locations, including AF447 and MH370. In this technological epoch, the international aviation community needs to provide assurance to the travelling public that the location of current-generation commercial aircraft is always known. It is unacceptable to do otherwise. In conclusion, the Team is unable to determine the real cause for the disappearance of MH370.

Courtesy CNN World

Malaysia Airlines Flight 370 (MH370) was a scheduled international passenger flight that disappeared on 8 March 2014 while flying from Kuala Lumpur International Airport, Malaysia, to its destination, Beijing Capital International Airport in China. The aircraft has not been recovered, and the cause of the disappearance remains unknown. With 239 people on board, the case of MH370 is one of the biggest mysteries in modern aviation history.

All times are UTC. Malaysia is UTC + 8



 ADV Ocean Shield deploys the Bluefin-21 autonomous underwater vehicle, which conducted the seafloor sonar survey from 14 April to 28 May.

A search-and-rescue effort was launched in southeast Asia soon after the aircraft’s disappearance. Following initial analysis of communications between the aircraft and a satellite, the surface search was moved to the southern Indian Ocean one week after the aircraft’s disappearance. Between 18 March and 28 April, nineteen vessels and 345 sorties by military aircraft searched over 4,600,000 square kilometres (1,800,000 sq mi). The final phase of the search was a bathymetric survey and sonar search of the sea floor, about 1,800 kilometres (970 nautical miles; 1,100 mi) south-west of Perth, Western Australia. With effect from 30 March 2014, the search was coordinated by the Joint Agency Coordination Centre (JACC), an Australian government agency established specifically to co-ordinate the search effort to locate and recover Flight 370, which primarily involved the Malaysian, Chinese, and Australian governments.

On 17 January 2017, the official search for Flight 370, which had proved to be the most expensive search operation in aviation history, was suspended after yielding no evidence of the aircraft apart from some marine debris on the coast of Africa. The final ATSB report, published on 3 October 2017, stated that the underwater search for the aircraft, as of 30 June 2017, had cost a total of US$155 million: the underwater search accounted for 86% of this amount, bathymetry 10% and programme management 4%; Malaysia supported 58% of the total cost, Australia 32%, and China 10%. The report also concluded that the location where the aircraft went down had been narrowed to 25,000, by using satellite images and debris drift analysis.

In January 2018, a private U.S. company called Ocean Infinity resumed the search for MH370 in the narrowed 25,000 area with the Norwegian ship Seabed Constructor. As of 13 May 2018, it had searched 86,000 square kilometres (33,000 sq. mi) of the area using eight autonomous underwater vehicles (AUVs). The planned search area of site 1, where the search began, is 33,012 square kilometres (12,746 sq. mi), while the extended search area covers a further 48,500 square kilometres (18,700 sq. mi). In April, a report by Ocean Infinity revealed that site 4 further northeast along the 7th arc had been added to the search plan. The search is ongoing.

Southeast Asia



The initial search area in Southeast Asia

The Kuala Lumpur Aeronautical Rescue Coordination Centre (ARCC) was activated at 2130 —four hours after communication was lost with the aircraft—to co-ordinate search and rescue efforts. Search efforts began in the Gulf of Thailand and South China Sea. On the second day of the search, Malaysian officials said that radar recordings indicated Flight 370 may have turned around; the search zone was expanded to include part of the Strait of Malacca. On 12 March, the chief of the Royal Malaysian Air Force announced that an unidentified aircraft—believed to be Flight 370—had travelled across the Malay peninsula and was last sighted on military radar 370 km (200 nmi; 230 mi) northwest of Penang Island; search efforts were subsequently increased in the Andaman Sea and Bay of Bengal.

Records of signals sent between the aircraft and a communications satellite over the Indian Ocean revealed that the aircraft had continued flying for almost six hours after its final sighting on Malaysian military radar. Initial analysis of these communications determined that Flight 370 was along one of two arcs—equidistant from the satellite—when its last signal was sent; the same day this analysis was publicly disclosed, 15 March, authorities announced they would abandon search efforts in the South China Sea, Gulf of Thailand, and Strait of Malacca to focus their efforts on the two corridors. The northern arc—from northern Thailand to Kazakhstan—was soon discounted as the aircraft would have had to pass through heavily militarised airspace and those countries claimed their military radar would have detected an unidentified aircraft entering their airspace.

Southern Indian Ocean


 The shifting search zones for Flight 370 in the Southern Indian Ocean. The inset shows the path taken by the vessel ADV Ocean Shield operating a towed pinger locator, acoustic detections, and the sonar search. The underwater phase (both the wide area search and priority area) is shown in pink.

The focus of the search shifted to the Southern Indian Ocean west of Australia and within Australia’s aeronautical and maritime Search and Rescue regions that extend to 75°E longitude. Accordingly, on 17 March, Australia agreed to lead the search in the southern locus from Sumatra to the southern Indian Ocean.

Initial search

From 18–27 March 2014 the search effort focused on a 305,000 km2 (118,000 sq mi) area about 2,600 km (1,400 nmi; 1,600 mi) south-west of Perth,[106] that Australian Prime Minister Tony Abbott said is “as close to nowhere as it’s possible to be” and which is renowned for its strong winds, inhospitable climate, hostile seas, and deep ocean floors.[107][108] Satellite imagery of the region was analysed; several objects of interest and two possible debris fields were identified on images captured between 16–26 March. None of these possible objects were found by aircraft or ships.[109]

Revised estimates of the radar track and the aircraft’s remaining fuel led to a move of the search 1,100 km (590 nmi; 680 mi) north-east of the previous area on 28 March, which was followed by another shift on 4 April.  Between 2 and 17 April an effort was made to detect the underwater locator beacons (ULBs; informally known as pingers attached to the aircraft’s flight recorders, whose batteries were expected to expire around 7 April. Australian naval cutter ADV Ocean Shield equipped with a towed pinger locator (TPL); China’s Haixun 01 equipped with a hand-held hydrophone; and the Royal Navy’s HMS Echo equipped with a hull-mounted hydrophone; were utilised in the search. Operators considered it a shot in the dark,  when comparing the vast search area with the fact that a TPL could only search up to 130 km2 (50 sq. mi) per day. Between 4–8 April several acoustic detections were made that were close to the frequency and rhythm of the sound emitted by the flight recorders’ ULBs; analysis of the acoustic detections determined that, although unlikely, the detections could have come from a damaged ULB.  A sonar search of the sea-floor near the detections was carried out between 14 April and 28 May without any sign of Flight 370.  In a March 2015 report, it was revealed that the calendar life of the battery for the ULB attached to Flight 370’s flight data recorder had expired in December 2012 and may not have been as capable.

Underwater search

In late June 2014, details of the next phase of the search were announced;  officials have called this phase the underwater search, despite the previous seafloor sonar survey. Continued refinement of analysis of Flight 370’s satellite communications identified a wide area search along the arc where Flight 370 was located when it last communicated with the satellite. The priority search area within the wide area search was in its southern extent. Some of the equipment to be used for the underwater search operates best when towed 200 m (650 ft) above the seafloor at the end of a 10 km (6 mi) cable. Available bathymetric data for this region was of poor resolution, thus necessitating a bathymetric survey of the search area before the underwater phase began. Commencing in May, the bathymetric survey charted around 208,000 km2 (80,000 sq. mi) of seafloor through 17 December 2014, when it was suspended for the ship conducting the survey to be mobilised in the underwater search.

The governments of Malaysia, China, and Australia agreed to thoroughly search 120,000 km2 (46,000 sq. mi) of seafloor. This phase of the search, which began on 6 October 2014, used three vessels equipped with towed deep-water vehicles that use side-scan sonar, multi-beam echo sounders, and video cameras to locate and identify aircraft debris. A fourth vessel participated in the search between January–May 2015; it had an autonomous underwater vehicle (AUV) to search areas which cannot be effectively searched by equipment on the other vessels.  Following the discovery of the flaperon on Réunion, the Australian Transport Safety Bureau (ATSB) reviewed its drift calculations for debris from the aircraft and, according to the JACC, was satisfied that the search area was still the most likely crash site. Reverse drift modelling of the debris, to determine its origin after 16 months, also supported the underwater search area, although reverse drift modelling is very imprecise over long periods. On 17 January 2017 Malaysia, China, and Australia jointly announced the suspension of the search for Flight 370.

2018 search

On 17 October 2017, Malaysia received proposals from three companies (the Dutch company Fugro being one of them) offering to continue the search for the aircraft.

In January 2018, a private U.S. company called Ocean Infinity announced it was going to resume the search in the narrowed 25,000 sq. km area. The attempt was approved by the Malaysian government, provided payment would be made only if the wreckage was found. Ocean Infinity chartered the Norwegian ship Seabed Constructor to conduct the search. Later that month it was reported the tracking system showed the vessel had reached the search zone on 21 January and started moving to 35.6°S 92.8°E, the most likely crash site according to the drift study by the Commonwealth Scientific and Industrial Research Organisation. As of 13 May 2018, Ocean Infinity has searched 86,000 square kilometres (33,000 sq. mi) of the area using eight autonomous underwater vehicles (AUVs). The planned search area of site 1, where the search was begun, is 33,012 square kilometres (12,746 sq. mi), while the extended area covers some more 48,500 square kilometres (18,700 sq. mi). All areas of site 1 (including areas beyond the originally planned search area of site 1), and site 2 have been searched. In April, a report by Ocean Infinity revealed that site 4 further northeast along the 7th arc had been added to the search plan. In May 2018, the final phase of the search will start before the weather limits Ocean Infinity’s ability to continue working this year. The search continues in site 3.

Marine debris

As of October 2017, twenty pieces of debris believed to be from 9M-MRO had been recovered from beaches in the western Indian Ocean. On 16 August 2017, the Australian Transport Safety Bureau released two reports: an analysis of a 23 March 2014 satellite imagery, two weeks after MH370 disappeared, classifying 12 objects in the ocean as probably man-made, and a drift study of these objects by the Commonwealth Scientific and Industrial Research Organisation, identifying the crash area with unprecedented precision and certainty, at 35.6°S 92.8°E, northeast of the main 120,000 km2 (46,000 sq. mi) underwater search zone.



Boeing 777 flaperon



Location of flaperon discovery relative to Flight 370’s flight path and the main search area


Currents within the Indian Ocean

The first item of debris identified as coming from flight 370 was the right (starboard) flaperon (a trailing edge control surface). It was discovered at the end of July 2015 on a beach in Saint-André, on Réunion, an island in the western Indian Ocean, about 4,000 km (2,200 nmi; 2,500 mi) west of the underwater search area. It was transported from Réunion—an overseas department of France—to Toulouse, where it was examined by France’s civil aviation accident investigation agency, the Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile (BEA), and a French defence ministry laboratory. Malaysia sent investigators to both Réunion and Toulouse. On 3 September, French officials announced that serial numbers found on internal components of the flaperon link it with certainty to Flight 370. These serial numbers were retrieved via borescope.

After discovery of the flaperon, French police conducted a search of the waters around Réunion for additional debris and came across a damaged suitcase which might be associated with Flight 370. The location is consistent with models of debris dispersal 16 months after an origin in the current search area, off the west coast of Australia. A Chinese water bottle and an Indonesian cleaning product were found in the same area.

France also conducted an aerial search for possible marine debris around the island, searching an area 120 by 40 km (75 by 25 mi) along the east coast of Réunion. Foot patrols along beaches to search for debris were also planned. Malaysia asked authorities in neighbouring states to be on alert for marine debris which could be from an aircraft. On 14 August, it was announced that no debris that could be related to Flight 370 had been found at sea off Réunion, but that some had been found on land. Air and sea searches for debris ended on 17 August.

Parts from the right stabiliser and right wing

In late February 2016, an object (with a stencilled text “NO STEP” on it) was found off the coast of Mozambique; early photographic analysis suggested it could have come from the aircraft’s horizontal stabiliser or the leading edges of the wings. It was found by Blaine Gibson on a sandbank in the Mozambique Channel, between Mozambique in eastern Africa and Madagascar; and in the same part of the southern Indian Ocean where the flaperon had been found the previous July. The fragment was sent to Australia where experts identified it as almost certainly a horizontal stabiliser panel from MH370.

In December 2015, Liam Lotter found a grey piece of debris on a beach in southern Mozambique, but only after he read in March 2016 about Gibson’s find (some 300 kilometres (190 mi) from his find) did his family alert authorities. It was flown to Australia for analysis. It carried a stencilled code 676EB, which identified it as part of a Boeing 777 flap track fairing, and the style in which the lettering was painted onto the fairing matched stencils used by Malaysia Airlines, making it almost certain that the part came from 9M-MRO.

The location where both pieces were retrieved was found to be consistent with the drift model performed by CSIRO, further corroborating they could have come from Flight 370.

Four other pieces

On 7 March 2016, more debris, possibly from the aircraft, was found on the island of Réunion. Ab Aziz Kaprawi, Malaysia’s Deputy Transport Minister, said that “an unidentified grey item with a blue border”, might be linked to Flight 370. Both Malaysian and Australian authorities, co-ordinating the search in the South Indian Ocean, sent teams to verify whether the debris was from the missing aircraft.

On 21 March 2016, South African archaeologist Neels Kruger found a grey piece of debris on a beach near Mossel Bay, South Africa that has an unmistakable partial logo of Rolls Royce, the manufacturer of the engines of the missing aircraft.  An acknowledgement of a possible part of an engine cowling was made by the Malaysian Ministry of Transport.  An additional piece of possible debris, suggested to have come from the interior of the aircraft, was found on the island of Rodrigues, Mauritius, in late March and was to be examined by Australian authorities. On 11 May 2016, the authority determined that these two pieces of debris were almost certainly from Flight 370.

Flap and further search

On 24 June 2016, the Australian Transport Minister, Darren Chester, said that a piece of aircraft debris had been found on Pemba Island, off the coast of Tanzania. It was handed over to the authorities so that experts from Malaysia could determine whether it was part of the aircraft. The Australian government released photos of the piece, believed to be an outboard flap from one of the aircraft’s wings, on 20 July. On 15 September, Malaysia’s transport ministry confirmed that the debris came from the missing aircraft. On 21 November 2016, families of the victims announced that they would take up the search for debris in Madagascar, in December.


International Participation

Malaysia set up a Joint Investigation Team (JIT), consisting of specialists from Malaysia, China, the UK, the US, and France, led according to ICAO standards by an independent investigator in charge. The team consists of an airworthiness group, an operations group, and a medical and human factors group. The airworthiness group will examine issues related to maintenance records, structures, and systems of the aircraft. The operations group will review flight recorders, operations, and meteorology. The medical and human factors group will investigate psychological, pathological, and survival factors. Malaysia also announced, on 6 April, that it had set up three ministerial committees—a Next of Kin Committee, a committee to organize the formation of the Joint Investigation Team, and a committee responsible for Malaysian assets deployed in the search effort. The criminal investigation is being led by the Royal Malaysia Police, assisted by Interpol and other relevant international law enforcement authorities.

On 17 March, Australia took control for coordinating search, rescue, and recovery operations. For the following six weeks, the Australian Maritime Safety Authority (AMSA) and ATSB worked to determine the search area, correlating information with the JIT and other government and academic sources, while the Joint Agency Coordination Centre (JACC) coordinated the search efforts. Following the fourth phase of the search, the ATSB took responsibility for defining the search area. In May, the search strategy working group was established by the ATSB to determine the most likely position on the aircraft at the 00:19 UTC satellite transmission. The group included aircraft and satellite experts from: Air Accidents Investigation Branch (UK), Boeing (US), Defence Science and Technology Group (Australia), Department of Civil Aviation,  Malaysia, Inmarsat (UK), National Transportation Safety Board (US), and Thales (UK).

The Malaysian Ministry of Transport issued an interim report entitled Factual Information: Safety Information for MH370 on 8 March 2015. As suggested by the report’s title, it focused on providing factual information and not analysis of possible causes of the disappearance. A brief update statement was provided in March 2016 regarding the status of the investigation. The final report was published 3 October 2017.

Analysis of satellite communication

The communications between Flight 370 and the satellite communication network operated by Inmarsat, which were relayed by the Inmarsat-3 F1 satellite, provide the only significant clues to the location of Flight 370 after disappearing from Malaysian military radar at 1822. These communications have also been used to deduce possible in-flight events.  The investigative team was challenged with reconstructing the flight path of Flight 370 from a limited set of transmissions with no explicit information about the aircraft’s location, heading, or speed.


 A depiction of an Inmarsat-3 series satellite. Flight 370 was in contact with Inmarsat-3 F1 (also known as “IOR” for Indian Ocean Region).

Aeronautical satellite communication (SATCOM) systems are used to transmit messages from the aircraft cockpit, as well as automated messages from on-board systems using the ACARS communications protocol, but may also be used to transmit FANS and ATN messages and provide voice, fax and data links using other protocols. The aircraft’s satellite data unit (SDU) is used to send and receive signals with the satellite communications network; it operates independently from other aircraft equipment that communicate through the SATCOM system, many using the ACARS protocol. Signals from the SDU are relayed by a satellite, which simply changes the signal’s frequency, and then received by a ground station, which processes the signal and, if applicable, routes it to its destination (e.g., Malaysia Airlines’ operations centre); signals to the aircraft are sent in reverse order. When the SDU is powered on and attempts to connect with the Inmarsat network, it transmits a log-on request, which the ground station acknowledges. This is, in part, to determine that the SDU belongs to an active service subscriber and used to determine which satellite should be used to transmit messages to the SDU. After connecting, if a ground station has not received any contact from a terminal for one hour, the ground station will transmit a log-on interrogation message, informally referred to as a ping; an active terminal responds automatically. The entire process of interrogating the terminal is referred to as a handshake.

 Communications from 1825 to 0019

Although the ACARS data link on Flight 370 stopped functioning between 01:07 and 02:03 MYT, the SDU remained operative. After last contact by primary radar west of Malaysia, the following events were recorded in the log of Inmarsat’s ground station at Perth, Western Australia (all times are UTC):

  • 1825:27 – 1st handshake – a log-on request initiated by aircraft
  • 1839:52 – Ground to aircraft telephone call, acknowledged by SDU, unanswered
  • 1941:00 – 2nd handshake (initiated by ground station)
  • 2041:02 – 3rd handshake (initiated by ground station)
  • 2141:24 – 4th handshake (initiated by ground station)
  • 2241:19 – 5th handshake (initiated by ground station)
  • 2313:58 – Ground to aircraft telephone call, acknowledged by SDU, unanswered
  • 0010:58 – 6th handshake (initiated by ground station)
  • 0019:29 – 7th handshake (initiated by aircraft); widely reported as a partial handshake, consisting of two transmissions:
  • 0019:29.416 – log-on request message transmitted by aircraft (7th partial handshake)
  • 0019:37.443 – log-on acknowledge message transmitted by aircraft, last transmission received from Flight 370
  • 0115: The aircraft did not respond to a ping.


A few deductions can be made from the satellite communications. The first is that the aircraft remained operational until at least 0019 —seven hours after final contact was made with air traffic control over the South China Sea. The varying burst frequency offset (BFO) values indicate the aircraft was moving at speed. The aircraft’s SDU needs location and track information to keep its antenna pointed towards the satellite, so it can also be deduced that the aircraft’s navigation system was operational.

Since the aircraft did not respond to a ping at 0115, it can be concluded that at some point between 0019 and 0115, the aircraft lost the ability to communicate with the ground station The log-on message sent from the aircraft at 0019:29 was log-on request. There are only a few reasons the SDU would transmit a log-on request, such as a power interruption, software failure, loss of critical systems providing input to the SDU, or a loss of the link due to the aircraft’s attitude. Investigators consider the most likely reason to be that it was sent during power-up after an electrical outage. At 08:19, the aircraft had been airborne for 7 h 38 min; the typical Kuala Lumpur-Beijing flight is 5​12 hours, so fuel exhaustion was likely. In the event of fuel exhaustion and engine flame-out, which would eliminate power to the SDU, the aircraft’s ram air turbine (RAT) would deploy, providing power to some instruments and flight controls, including the SDU. Approximately 90 seconds after the 1825 handshake—also a log-on request—communications from the aircraft’s inflight entertainment system were recorded in the ground station log. Similar messages would be expected following the 0019 handshake, but none were received, supporting the fuel-exhaustion scenario.



A heat map indicating the probable location of missing Flight 370 based on a Bayesian method analysis of possible flight paths by Australia’s Defence Science and Technology Group.

Two parameters associated with these transmissions that were recorded in a log at the ground station were key to the investigation:

  • Burst time offset (BTO) – the time difference between when a signal is sent from the ground station and when the response is received. This measure is proportional to twice the distance from the ground station via the satellite to the aircraft and includes the time that the SDU takes between receiving and responding to the message and time between reception and processing at the ground station. This measure was analyzed to determine the distance between the satellite and the aircraft at the time each of the seven handshakes occurred, and thereby defining seven circles on the Earth’s surface the points on whose circumference are equidistant from the satellite at the calculated distance. Those circles were then reduced to arcs by eliminating those parts of each circle that lay outside the aircraft’s range.
  • Burst frequency offset (BFO) – the difference between the expected and received frequency of transmissions. The difference is caused by Doppler shifts as the signals travelled from the aircraft to the satellite to the ground station; the frequency translations made in the satellite and at the ground station; a small, constant error (bias) in the SDU that results from drift and ageing; and compensation applied by the SDU to counter the Doppler shift on the uplink. This measure was analyzed to determine the aircraft’s speed and heading, but multiple combinations of speed and heading can be valid solutions.

By combining the distance between the aircraft and satellite, speed, and heading with aircraft performance constraints (e.g. fuel consumption, possible speeds and altitudes), investigators generated candidate paths that were analyzed separately by two methods. The first assumed the aircraft was flying on one of the three autopilot modes (two are further affected by whether the navigation system used magnetic north or true north as a reference), calculated the BTO and BFO values along these routes, and compared them with the values recorded from Flight 370. The second method generated paths which had the aircraft’s speed and heading adjusted at the time of each handshake to minimize the difference between the calculated BFO of the path and the values recorded from Flight 370. A probability distribution for each method at the BTO arc of the sixth handshake of the two methods was created and then compared; 80% of the highest probability paths for both analyses combined intersect the BTO arc of the sixth handshake between 32.5°S and 38.1°S, which can be extrapolated to 33.5°S and 38.3°S along the BTO arc of the seventh handshake.

Possible in-flight events

Power interruption

The SATCOM link functioned normally from pre-flight (beginning at 1600 until it responded to a ground-to-air ACARS message with an acknowledge message at 1707. Ground-to-air ACARS messages continued to be transmitted to Flight 370 until Inmarsat’s network sent multiple Request for Acknowledge messages at 1803, without a response from the aircraft. At some time between 1707 and 1803, power was lost to the SDU. At 1825, the aircraft’s SDU sent a “log-on request”. It is not common for a log-on request to be made in-flight, but it could occur for multiple reasons. An analysis of the characteristics and timing of these requests suggest a power interruption in-flight is the most likely culprit. As the power interruption was not due to engine flame-out, per ATSB, it may have been the result of manually switching off the aircraft’s electrical system.

Unresponsive crew or hypoxia

An analysis by the ATSB comparing the evidence available for Flight 370 with three categories of accidents—an in-flight upset (e.g., stall), a glide event (e.g., engine failure, fuel exhaustion), and an unresponsive crew or hypoxia event—concluded that an unresponsive crew or hypoxia event best fit the available evidence for the five-hour period of the flight as it travelled south over the Indian Ocean without communication or significant deviations in its track, likely on autopilot. No consensus exists among investigators on the unresponsive crew or hypoxia theory. If no control inputs were made following flameout and the disengagement of autopilot, the aircraft would likely have entered a spiral dive and entered the ocean within 20 nautical miles (37 km; 23 mi) of the flameout and disengagement of autopilot. The analysis of the flaperon showed that the landing flaps were not extended, supporting the spiral dive at high speed.

 Possible causes of disappearance

Passenger involvement

Two men boarded Flight 370 with stolen passports, which raised suspicion in the immediate aftermath of its disappearance. The passports, one Austrian and one Italian, were reported stolen in Thailand within the preceding two years. Interpol stated that both passports were listed on its database of lost and stolen passports and that no check had been made against its database. Malaysia’s Home Minister, Ahmad Zahid Hamidi, criticized his country’s immigration officials for failing to stop the passengers travelling on the stolen European passports. The two one-way tickets purchased for the holders of the stolen passports were booked through China Southern Airlines. It was reported that an Iranian had ordered the cheapest tickets to Europe via telephone in Bangkok, Thailand, and paid in cash. The two passengers were later identified as Iranian men, one aged 19 and the other 29, who had entered Malaysia on 28 February using valid Iranian passports. The head of Interpol said the organization was “inclined to conclude that it was not a terrorist incident”. The two men were believed to be asylum seekers.

United States and Malaysian officials were reviewing the backgrounds of every passenger named on the manifest. On 18 March, the Chinese government announced that it had checked all of the Chinese citizens on the aircraft and ruled out the possibility that any were involved in destruction or terror attacks. One passenger who worked as a flight engineer for a Swiss jet charter company was briefly suspected as a potential hijacker because he was thought to have the relevant skill set.

Crew involvement

US intelligence officers believe the most likely explanation was that someone in the cockpit of Flight 370 re-programmed the aircraft’s autopilot before it travelled south across the Indian Ocean. Police searched the homes of the pilots and seized financial records for all 12 crew members, including bank statements, credit card bills and mortgage documents. On 2 April 2014, Malaysia’s Police Inspector-General said that more than 170 interviews had been conducted as part of Malaysia’s criminal investigation, including interviews with family members of the pilots and crew.

Media reports have claimed that Malaysian police have identified Captain Shah as the prime suspect if human intervention is proven to be the cause of Flight 370’s disappearance. The United States’ Federal Bureau of Investigation (FBI) reconstructed the deleted data from Captain Shah’s home flight simulator; a Malaysian government spokesman indicated that nothing sinister had been found on it. The preliminary report issued by Malaysia in March 2015 stated that there was no evidence of recent or imminent significant financial transactions carried out by any of the pilots or crew and that analysis of the behaviour of the pilots on CCTV showed no significant behavioural changes.

In 2016, a leaked American document stated that a route on the pilot’s home flight simulator closely matching the projected flight over the Indian Ocean was found during the FBI analysis of the hard drive of the computer used for the flight simulator. This was later confirmed by the ATSB, although it stressed that this did not prove the pilot’s involvement. It was similarly confirmed by the Malaysian government.


Flight 370 was carrying 10,806 kg (23,823 lb) of cargo, of which four ULDs of mangosteens and 221 kg (487 lb) of lithium-ion batteries are of interest, according to Malaysian investigators. The four ULDs of mangosteens were loaded into the aft cargo bay of the aircraft. The lithium-ion batteries were divided among two pallets in the forward cargo bay and one pallet placed in the rear of the aft cargo bay.

The lithium-ion batteries were contained in a 2,453 kg (5,408 lb) consignment being transported between Motorola Solutions facilities in Bayan Lepas, Malaysia, and Tianjin, China; the rest of the consignment consisted of walkie-talkie chargers and accessories. The batteries were assembled on 7 March and transported to the Penang Cargo Complex to be transported by MASkargo—Malaysia Airlines’ cargo subsidiary—to be loaded onto a lorry to transport it to Kuala Lumpur International Airport and onwards by air to Beijing.[18]:104 At the Penang Cargo Complex, the consignment was inspected by MASkargo employees and Malaysian customs officials, but did not go through a security screening before the truck was sealed for transfer to the airport. The consignment did not go through any additional inspections at Kuala Lumpur International Airport before it was loaded onto Flight 370. Because the batteries were packaged in accordance with IATA guidelines, they were not regulated as dangerous goods.:106 Lithium-ion batteries can cause intense fires if they overheat and ignite, which has led to strict regulations on their transport aboard aircraft. A fire fueled by lithium-ion batteries caused the crash of UPS Airlines Flight 6, and lithium-ion batteries are suspected to have caused a fire which resulted in the crash of Asiana Airlines Flight 991; both were cargo aircraft. Some airlines have stopped carrying bulk shipments of lithium-ion batteries on passenger aircraft, citing safety concerns.

A 4,566 kg (10,066 lb) consignment of mangosteens was aboard Flight 370. The mangosteens were loaded into four ULDs at Kuala Lumpur International Airport and inspected by officials from Malaysia’s Federal Agriculture Marketing Authority before being loaded onto Flight 370. According to the head of Malaysian police, Inspector-General Tan Sir Khalid Abu Bakar, the people who handled the mangosteens and the Chinese importers were questioned to rule out sabotage.


Public communication from Malaysian officials regarding the loss of the flight was initially beset with confusion. The Malaysian government and the airline released imprecise, incomplete, and sometimes inaccurate information, with civilian officials sometimes contradicting military leaders. Malaysian officials were criticized for such persistent release of contradictory information, most notably regarding the last location and time of contact with the aircraft.

Although Malaysia’s acting Transport Minister Hishammuddin Hussein, who is also the country’s Defence Minister, denied the existence of problems between the participating countries, academics said that because of regional conflicts, there were genuine trust issues involved in co-operation and sharing intelligence, and that these were hampering the search. International relations experts said entrenched rivalries over sovereignty, security, intelligence, and national interests made meaningful multilateral co-operation very difficult. A Chinese academic made the observation that the parties were searching independently; thus it was not a multilateral search effort. The Guardian noted the Vietnamese permission given for Chinese aircraft to overfly its airspace as a positive sign of co-operation. Vietnam temporarily scaled back its search operations after the country’s Deputy Transport Minister cited a lack of communication from Malaysian officials despite requests for more information. China, through the official Xinhua News Agency, said that the Malaysian government ought to take charge and conduct the operation with greater transparency, a point echoed by the Chinese Foreign Ministry days later.

Malaysia had initially declined to release raw data from its military radar, deeming the information too sensitive, but later acceded. Defence experts suggested that giving others access to radar information could be sensitive on a military level, for example: The rate at which they can take the picture can also reveal how good the radar system is. One suggested that some countries could already have had radar data on the aircraft but were reluctant to share any information that could potentially reveal their defence capabilities and compromise their own security. Similarly, submarines patrolling the South China Sea might have information in the event of a water impact and sharing such information could reveal their locations and listening capabilities.

Criticism was also levelled at the delay of the search efforts. On 11 March, three days after the aircraft disappeared, British satellite company Inmarsat (or its partner, SITA) had provided officials with data suggesting the aircraft was nowhere near the areas in the Gulf of Thailand and the South China Sea being searched at that time and may have diverted its course through a southern or northern corridor. This information was publicly acknowledged and released by Najib only on 15 March in a press conference. Explaining why information about satellite signals had not been made available earlier, Malaysia Airlines said that the raw satellite signals needed to be verified and analyzed so that their significance could be properly understood before it could publicly confirm their existence. Hishammuddin said that Malaysian and US investigators had immediately discussed the Inmarsat data upon receiving them on 12 March, and on two occasions, both groups agreed that it needed further processing and sent the data to the US twice for this purpose. Data analysis was completed on 14 March: by then, the AAIB had independently arrived at the same conclusion.

In June 2014, relatives of passengers on Flight 370 began a crowdfunding campaign on Indiegogo to raise US$100,000—with a goal of raising US$5 million—as a reward to encourage anyone who knows the location of Flight 370 or the cause of its disappearance to reveal what they know. The campaign, which ended 8 August 2014, raised US$100,516 from 1007 contributors.

Air transport industry

The fact that, in a digitally-connected world, a modern aircraft could disappear was met with surprise and disbelief by the public. While changes in the aviation industry often take years to be implemented, airlines and air transport authorities responded swiftly to act on several measures to reduce the likelihood of a similar incident.

Aircraft tracking

The International Air Transport Association (IATA)—an industry trade organization representing over 240 airlines (representing 84% of global air traffic)—and the International Civil Aviation Organization (ICAO)—the United Nations’ civil aviation body—began working on implementing new measures to track aircraft in flight in real time. The IATA created a task force (which included several outside stakeholders) to define a minimal set of requirements that any tracking system must meet, allowing airlines to decide the best solution to track their aircraft. The IATA’s task force planned to come up with several short-, medium-, and long-term solutions to ensure that information is provided in a timely manner to support search, rescue, and recovery activities in the wake of an aircraft accident. The task force was expected to provide a report to the ICAO on 30 September 2014, but on that day said that the report would be delayed, citing the need for further clarification on some issues. In December 2014, the IATA task force recommended that, within 12 months, airlines track commercial aircraft in no longer than 15-minute intervals, although it still has not released its report and full details of proposed changes. The IATA itself did not support the deadline, which it believes cannot be met by all airlines, but the proposed standard has the support of the ICAO. Although the ICAO can set standards, it has no legal authority and such standards must be adopted by member states.

In 2016, the ICAO adopted a standard that, by November 2018, all aircraft over open ocean report their position every 15 minutes. In March, the ICAO approved an amendment to the Chicago Convention requiring new aircraft manufactured after 1 January 2021 to have autonomous tracking devices which could send location information at least once per minute in distress circumstances.

In May 2014, Inmarsat said that it would offer its tracking service for free to all aircraft equipped with an Inmarsat satellite connection (which amounts to nearly all commercial airliners). Inmarsat also changed the time period for handshakes with its terminals from one hour to 15 minutes.


There was a call for automated transponders after the 11 September 2001 terrorist attacks; no changes were made, as aviation experts preferred flexible control, in case of malfunctions or electrical emergencies. In the wake of Flight 370, the air transport industry was still resistant to the installation of automated transponders, which would likely entail significant costs. Pilots also criticized changes of this kind, insisting on the need to cut power to equipment in the event of a fire. Nonetheless, new types of tamper-proof circuit breakers were being considered.

Flight recorders


 Diagram of location of ship, thermocline, towed pinger locater at end of tow cable, and blackbox pinger. Detection of the acoustic signal from the ULBs must be made below the thermocline and within a maximum range, under nominal conditions, of 2,000–3,000 m (6,600–9,800 ft). With a ULB battery life of 30–40 days, searching for the important flight recorders is very difficult without precise coordinates of the location the aircraft entered the water.

The frenzied search for the flight recorders in early April 2014, due to the 30-day battery life of the underwater locator beacons (ULBs) attached to them, brought attention to the limitations of the ULBs. The distance the signal from the ULBs can be detected from is 2,000–3,000 m (6,600–9,800 ft), or 4,500 m (14,800 ft) under favourable conditions. Even if the flight recorders are located, the cockpit voice recorder memory has capacity to store only two hours of data, continuously recording over the oldest data. This length complies with regulations and it is usually only data from the last section of a flight that are needed to determine the cause of an accident. The events which caused Flight 370 to divert from its course and disappear happened more than two hours before the flight ended. Given these limitations and the importance of the data stored on flight recorders, Flight 370 has brought attention to new technologies that enable data streaming to the ground.

A call to increase the battery life of ULBs was once again made after the unsuccessful initial search in 2009 for the flight recorders on Air France Flight 447, which were not located until 2011. A formal recommendation that the ULB design be upgraded to offer a longer battery life or to make the recorders ejectable had been included in the final report of the board of inquiry into the loss of South African Airways Flight 295 over the Indian Ocean in 1987; the ICAO made such a recommendation in 2014, with implementation by 2018.The European Aviation Safety Agency (EASA) issued new regulations requiring that the transmitting time of ULBs fitted to aircraft flight recorders be increased from 30 to 90 days. The agency proposed a new underwater locator beacon with a greater transmitting range to be fitted to aircraft flying over oceans. In June 2015, Dukane, a manufacturer of underwater locator beacons, began selling beacons with a 90-day battery life.

In March 2016, the ICAO adopted several amendments to the Chicago Convention to address issues raised by Flight 370’s disappearance. For aircraft manufactured after 2020, cockpit voice recorders will be required to record at least 25 hours of data, so that they record all phases of a flight. Aircraft designs approved after 2020 will need to have a means to recover the flight recorders, or the information they contain, before the recorders sink below water. This provision is performance-based so that it can be accomplished by different techniques, such as streaming flight recorder data from aircraft in distress or using flight recorders which eject from aircraft and float on the water’s surface. The new regulations will not require modifications to existing aircraft.

Safety recommendations

In January 2015, the US National Transportation Safety Board cited Flight 370 and Air France Flight 447 when it issued eight safety recommendations related to locating aircraft wreckage in remote or underwater locations; and repeated recommendations for a crash-protected cockpit image recorder and tamper-resistant flight recorders and transponders.

Courtesy of


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