Reports/The Operational Search for MH370/History of the flight

MH370 DECODED
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History of the flight

Kuala Lumpur to waypoint IGARI

On 7 March 2014 at 1642 UTC[1], a Boeing 777-200ER aircraft, registered 9M-MRO and operating as Malaysia Airlines flight 370 (MH370), departed from runway 32R at Kuala Lumpur International Airport on an international scheduled passenger flight to Beijing, People’s Republic of China. On board the aircraft were 239 persons, comprising 12 crew and 227 passengers[2]. Following take-off, the aircraft was cleared by air traffic control (ATC) at Kuala Lumpur Air Traffic Control Centre to climb to 18,000 ft (FL180)[3] . The crew were approved to cancel the Standard Instrument Departure and track direct to the Instrument Flight Rules (IFR) waypoint IGARI (Figure 3).


Figure 3: History of recorded events

The Operational Search for MH370 Figure 3

Source: ATSB, using Ministry of Transport Malaysia data


Subsequently, the aircraft was cleared to climb to FL250 and then to the planned cruising level of FL350. At 1701:17, the Pilot-in-Command (PIC) of MH370 reported maintaining FL350.

At 1707:29, the Aircraft Communications Addressing and Reporting System (ACARS) transmitted the flight’s first ‘B777 position report’ via the aircraft’s satellite communication system. Information in this report included the total fuel load of 43,800 kg, enough fuel for MH370 to remain airborne until approximately 0012. A position report was normally transmitted every 30 minutes, however the report at 1707:29 was the last ACARS report received from the aircraft.

Prior to the aircraft reaching waypoint IGARI, which denoted the border of the Vietnamese flight information region, Kuala Lumpur Air Traffic Control Centre instructed the crew to contact Ho Chi Minh Air Traffic Control Centre (Vietnam) on a radio frequency of 120.9 MHz. At 1719:30, the PIC of MH370 acknowledged the instruction with ‘Good night Malaysia Three Seven Zero.’ This was the last recorded radio transmission from the aircraft.


Notes
  1. Coordinated Universal Time (UTC) is used throughout this report. Malaysia time (MYT) was UTC +8 Hrs.
  2. A more detailed history of the flight has been published by the Ministry of Transport Malaysia and is available here: www.mh370.gov.my/index.php/en/media2/transcript/category/13-mh370-safety-investigation-public
  3. Flight levels give an approximate altitude in hundreds of feet. FL180 is approximately 18,000 ft.

Waypoint IGARI to waypoint MEKAR

The aircraft was fitted with a transponder that permitted ground-based secondary surveillance radars (SSR) to track it. A subsequent review of recorded ATC radar data revealed that the aircraft passed waypoint IGARI at 1720:31 and that the Mode S transponder symbol of the aircraft was not detected on Malaysian ATC radar after 1720:36. A matching SSR target captured by Vietnamese radar at Conson Island was no longer detected after 1720:33[1].

Some radars, called primary surveillance radars (PSR), can detect an aircraft without relying on a transponder, usually at a much shorter range than SSR. Recordings from a civilian PSR at Kota Baru in the north of Malaysia and a military PSR on Penang Island jointly showed a target that matched the time and location of MH370’s last SSR position. While the recorded primary radar data was not continuous, the target could be followed with no ambiguity with other radar returns in the area. The limited fidelity of the PSR tracking data allowed the aircraft’s speed, location, and altitude to be approximated from IGARI onwards.

From IGARI, the aircraft apparently made a 40° turn to the right and then a 180° turn to the left to track almost directly back across the Malay Peninsula, in the general direction of Penang Island. The aircraft passed over or near IFR waypoints ABTOK, KADAX and GOLUD (which are within 3 NM of each other) and later PUKAR.

The aircraft made a slow right turn south of Penang Island. A mobile telephone registered to the aircraft’s first officer was detected by a mobile telecommunications tower at Bandar Baru Farlim Penang at 1752:27, when the aircraft was south of Penang. There was no record of communications having been made or attempted using this telephone[2].

Radar data shows the aircraft then headed to the northwest, eventually aligning with published air route N571 from IFR waypoint VAMPI. The validity of this section of the radar data was verified using the track of a commercial flight that followed N571 about 33 NM behind MH370. The aircraft continued to the northwest until a final radar position for the aircraft was recorded approximately 10 NM beyond IFR waypoint MEKAR at 1822:12 (Figure 3). There were no reports of the aircraft being detected by any radar after this time. Key events are summarised in Table 3.

 

Table 3: Key recorded events

Recorded Event Time (UTC)
Event 1: MH370 departed Kuala Lumpur International Airport 1642
Event 2: PIC reported maintaining FL350 1701:17
Event 3: ACARS report transmitted 1707:29
Event 4: Last radio transmission from MH370 1719:30
Event 5: Aircraft passed over waypoint IGARI 1720:31
Event 6: Last recorded secondary surveillance radar position 1721:13
Event 7: First officer’s mobile phone detected by Penang communications system 1752:27
Event 8: Last primary surveillance radar position 1822:12

Source: Ministry of Transport Malaysia, Royal Malaysian Police


  1. From 1739:03 onwards, Malaysian and Vietnamese controllers attempted to contact the aircraft by radio without success. A distress phase was formally initiated by Malaysian ATC at 2232:00.
  2. This information was obtained by the Royal Malaysian Police and reported to the Ministry of Transport Malaysia.
    Though a formal report was not available to the ATSB, information relevant to the search was shared.

Waypoint MEKAR onwards

At 1825:27, about three minutes after the last primary radar return, the aircraft’s satellite data unit (SDU) initiated a log-on sequence via the Inmarsat Indian Ocean Region I-3 satellite to the ground station in Perth, Western Australia. The log-on sequence and timings of subsequent SDU communications were recorded by the Inmarsat ground station, including several automated handshakes[1] initiated by either the ground station or the aircraft, and two unanswered ground-to-air satellite telephone call attempts (made by the aircraft operator in an attempt to contact the aircraft). This information showed that the flight continued for almost six hours after the last radar return (Table 4).

Table 4: Satellite communications after passing waypoint MEKAR

Recorded SDU communicationsTime (UTC)
Handshake 1 initiated by the aircraft 1825:27
Unanswered ground to air telephone call 1839:52
Handshake 2 initiated by the ground station 1941:00
Handshake 3 initiated by the ground station 2041:02
Handshake 4 initiated by the ground station 2141:24
Handshake 5 initiated by the ground station 2241:19
Unanswered ground to air telephone call 2313:58
Handshake 6 initiated by the ground station 0010:58
Handshake 7 initiated by the aircraft 0019:29
Aircraft did not respond to log-on interrogation from the satellite earth ground station (failed handshake). 0115:56

Source: Inmarsat

As part of routine logging, Inmarsat recorded the burst timing offset (BTO) and burst frequency offset (BFO) information for each handshake. Though not intended for this purpose, the BTO could be used to find the distance between the aircraft and the satellite at the time of each handshake. A series of seven rings, joining points on the earth’s surface equidistant from the satellite, shows the range of possible locations of the aircraft at the time of each handshake (Figure 4). By taking the maximum speed of the aircraft into account, the BTO derived rings could be reduced in length to arcs (there are some areas of the rings the aircraft simply could not have reached).


Figure 4 BTO ring solutions for MH370

The Operational Search for MH370 Figure 4

Source: Google Earth, annotated by ATSB


The BFO was influenced by the speed of the aircraft relative to the satellite which is affected by the aircraft position, direction and speed of travel, and the satellite’s own movement. Analysis of the BFO metadata revealed that the aircraft headed south from some point beyond waypoint MEKAR to a region in the southern Indian Ocean. This analysis was later supported by studying[2] the drift of MH370 debris which was found on the shorelines of eastern African nations in 2015 and 2016.

Analysis of the last satellite communication at 0019.29, which was an unscheduled log-on request from the aircraft, determined that it was probably the result of the aircraft having exhausted its fuel and then being powered by the auxiliary power unit. Based on the last transmitted fuel status and aircraft performance data the time that this occurred generally aligned with the expected time of fuel exhaustion. It was concluded that the aircraft probably impacted the ocean relatively close to the time this last transmission was made, which is referred to as the 7th arc.

The methodologies for calculating the aircraft’s possible flight paths were outlined in the ATSB’s reports:

  • MH370 – Definition of Underwater Search Areas ( released 26 June 2014, amended 18 August 2014, amended 30 July 2015)
  • MH370 – Flight Path Analysis Update (released 8 October 2014)
  • MH370 – Definition of Underwater Search Areas (released 3 December 2015, amended 10 December 2015)
  • MH370 – Search and debris examination update (released 2 November 2016, amended 2 December 2016)
  • MH370 – First Principles Review (released 20 December 2016)

  1. In satellite communications, a handshake is a series of signalling messages that establish or maintain a communication channel.
  2. Refer to the CSIRO reports prepared for the ATSB: The search for MH370 and ocean surface drift- parts I, II and III.

Source: The Operational Search for MH370, Australian Transport Safety Bureau, 3 October 2017
https://www.atsb.gov.au/publications/investigation_reports/2014/aair/ae-2014-054/




Extracts from The Operational Search for MH370 have been included here for reference purposes, particularly the sections which relate to the history of the flight; times and events; the aircraft's satellite data unit (SDU); and the Pilot in Command’s flight simulator.