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Straits of Malacca to Andaman Sea

From 1:52 MYT to 2:22:12 MYT Saturday, 8 March 2014
(17:52 UTC to 18:22:12 UTC Friday, 7 March 2014)

1. Last Primary Radar Observation at 1822:12 UTC (0222:12 MYT)

The last Military primary radar observation of MH370 is described in the Safety Investigation Report MH370/01/2018 as follows:-

At 1803:09 UTC [0203:09 MYT] the “blip” disappeared, only to reappear at 1815:25 UTC [0215:25 MYT] until 1822:12 UTC [0222:12 MYT], about 195 nm from Butterworth, on a heading of 285°, speed of 516 kt and at an altitude of 29,500 ft.

The radar track of MH370 is shown in Figure 2 opposite.

  • The civilian Air Traffic Control radar track (secondary radar) is shown as the pale line from Kuala Lumpur to the last secondary radar observation at 1722 UTC (0122 MYT).
  • The Military primary radar track is shown as a yellow line from the turnback near waypoint IGARI, across Malaysia and north-west along the Malacca Strait.

The exact latitude and longitude of MH370 at 0222:12 MYT is not provided, but from the graphic it can be seen that MH370 is located north-east of the tip of Sumatra and heading north-west towards the Andaman Sea.

ATSB MH370 - Definition of Underwater Search Areas 2014 Figure 2

Figure 2: MH370 flight path derived from primary and secondary radar data
Source: MH370 - Definition of Underwater Search Areas[1], Australian Transport Safety Bureau, 2014.

2. SATCOM Log-on Request at 1825:27 UTC (0225:27 MYT)

At 0225:27 MYT the satellite data unit (SDU) on MH370 seems to have recovered from a power interruption and initiated a log-on sequence with the Inmarsat satellite communication system. The satellite data link was lost some time between 1707:48 and 1803:41 UTC, possibly due to a loss of electrical power. The reasons for these events is discussed in the Safety Investigation Report MH370/01/2018 and the extracts linked from each event in the Timeline.

Investigators have called this log-on event the first ‘handshake’ - because it was a successful communication between the aircraft and the ground station via the satellite.

The other benefit of this communication is the metadata associated with this transmission - the Burst Timing Offset (BTO) provides an indication of the distance of the aircraft from the satellite at that time. This is shown graphically (with other 'handshakes') as a series of concentric circles, or rings, in Figure 18 below. Since only part of the ring is technically feasible, the valid section is called an 'arc'.

In the diagram opposite, the position of MH370 is shown on this first, 1825 UTC arc.

It seems unlikely that the heading has changed significantly in the short period since the last primary radar observation.

Bayesian Methods in the Search for MH370 Fig 4.3

Fig. 4.3 18:02 prediction to 18:25, shown in yellow. The Malaysian military radar track is shown in white, on the right. The near-vertical white line on the left corresponds to the 18:25 BTO arc.
Source: Bayesian Methods in the Search for MH370[2]

Malaysian Military Radar

On this page the military radar observations provide a context and background for other events related to flight MH370 during the 'Air Turnback' - from the loss of contact to the last primary radar observation as MH370 was heading towards the Andaman Sea, west of Malaysia.

A 'blip' believed to be MH370 was observed from 1721:13 UTC [0121:13 MYT] to 1822:12 UTC [0222:12 MYT]

A 'blip' is a spot of light on a radar screen indicating the position of a detected aircraft.

Figure 3: History of recorded events

The Operational Search for MH370 Figure 3

Source: ATSB, using Ministry of Transport Malaysia data

01:52:31 MYT

At 0152:31 MYT the aircraft was observed by military radar to be at 10 nm south of Penang Island on a heading of 261°, with a speed of 525 knots at an altitude of 44,700 ft (above the service ceiling of 43,100 ft).

02:01:59 to 02:03:09 MYT

At 0201:59 MYT the aircraft was in the area of Pulau Perak. Military radar data showed the “blip” on a heading of 022°, speed of 492 kt and altitude at 4,800 ft.

The 'blip' disappeared from radar screen at 0203:09 MYT.

02:03:23 MYT

Malaysia Airlines ODC sent an ACARS message to MH370, direct to the cockpit printer. The ACARS message requested the crew to contact the HCM ACC immediately. The incoming downlink message at 1803:24 UTC showed the message failed to reach the aircraft. The message was retransmitted (automatically) at least seven times. On each occasion, an automated downlink message by ACARS showed ‘failed’.

02:03:41 MYT

GES initiates a DATA-2 ACARS transmission (uplink), but receives no acknowledgement from the SATCOM. Therefore, the SATCOM Link was lost at sometime between 1707:48 and 1803:41 (UTC).

02:05:11 MYT

GES initiates a DATA-2 ACARS transmission, but receives no acknowledgement from the SATCOM, indicating that there is still no SATCOM link at this time.

02:15:25 to 02:22:12 MYT

On Military radar a 'blip' reappeared at 0215:25 MYT and was observed until it finally disappeared at 0222:12 MYT.

At 0222:12 MYT the 'blip' was about 195 nm from Butterworth, on a heading of 285° - towards waypoint MEKAR on Airway N571 - with a speed of 516 kt and an altitude of 29,500 ft.

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