Factual Information 2015:1.9 Communications/1.9.5 Satcom/1.9.5.4
This page contains an extract from MH370/01/15 Factual Information which accompanied the (first) Interim Statement released by The Malaysian ICAO Annex 13 Safety Investigation Team for MH370 on 8th March 2015.
1.9.5.4 SATCOM Ground Station Logs - Key Observations in Chronological Order
1. 1250:19 - Prior to take-off, the SATCOM initiates a normal Log-On as Class 1 (data only capable) via the Pacific Ocean Region (POR) I-3 satellite, using the Low Gain Antenna (LGA) subsystem. No flight ID is sent to the GES at this time. This is the first SATCOM activity recorded at the GES since 0802:27.
2. 1555:57 - The SATCOM initiates a normal Log On Renewal as Class 1 (data only capable) via the POR I-3 satellite, using the LGA subsystem, this time with a valid Flight ID.
3. 1557:49 - The SATCOM initiates a normal Log-On as Class 3 (voice and data capable) via the POR I-3 satellite, using the High Gain Antenna (HGA) subsystem, with a valid Flight ID.
4. 1559:57 - The SATCOM initiates a Log-On handover as Class 3 (voice and data capable) to the IOR I-3 satellite, using the HGA subsystem, with a valid Flight ID.
5. 1642:04 - After take-off, the IFE SMS e-mail application sends a normal beginning-of-flight message.
a. The message contained the correct AES ID, Flight ID "MAS370", origin airport "WMKK", and destination airport "ZBAA".
b. This indicates that the IFE was receiving the Flight ID, origin airport and destination airport from AIMS and the ICAO (AES) ID from the SDU at this time.
6. 1707:48 - Last Acknowledged DATA-2 ACARS Message. No further SATCOM Data-2 ACARS messages or acknowledgements were received at the GES for the remainder of the flight.
7. 1803:41 - GES initiates a DATA-2 ACARS transmission (uplink), but receives no acknowledgement from the SATCOM.
a. Therefore, the SATCOM Link was lost at sometime between 1707:48 and 1803:41.
b. There is no evidence of a cockpit-initiated manual Log-Off of the SATCOM.
8. 1805:11 - 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.
9. 1825:27 - SATCOM Log-On, initiated from the aircraft terminal.
a. This is the first ‘handshake’.
b. This marks the end of the link lost period that began at sometime between 1707:48 and 1803:41.
10. 1825:34 – SATCOM Log-On, successfully completed.
a. The SATCOM link becomes available (for both voice and data – Class 3) once more and normal SATCOM operation resumes (except that there is no Data-2 ACARS traffic which is normally transmitted at least once every 30 minutes).
b. No Flight ID was sent to the GES during the Log-On.
c. The GES recorded abnormal BFOs for the SATCOM Log-On Request and Log-On Acknowledge transmissions.
11. 1827:03 – The IFE sets up a Data-3 ground connection (X.25 circuit) over SATCOM for an SMS/e-mail application after the SATCOM link is re-established.
12. 1828:05 – The IFE sets up a Data-3 ground connection (X.25 circuit) over SATCOM for a BITE application after the SATCOM link is re-established.
13. 1839:52 – Ground to Air Telephony Call Placed from a number with country code 60
a. Q10 Airline Operational Communications (AOC) Priority Level
b. This call would have been routed to the cockpit and should have resulted in a chime and an incoming visual annunciation on the Audio Control Panels (ACPs), and, if the appropriate SATCOM page was selected, then also on one or more MCDU.
c. The GES logs show zero duration, indicating that the call went unanswered. Note that there are two methods for the answering of an incoming call: Either by pressing the relevant Line Select Key on an MCDU, or by keying a microphone.
14. 1840:56 – The GES logs show that the unanswered Ground to Air telephony call was cleared by the calling party.
15. 1941:00 – Log-On Interrogation by the Perth GES, with a response from the SATCOM
a. This is the second ‘handshake’, whereby the GES inactivity timer has expired and the GES has sent a message to interrogate the status of the SATCOM.
b. The SATCOM responded normally and the SATCOM link was therefore available at this time.
16. 2041:02 – Log-On Interrogation by the Perth GES, with a response from the SATCOM
a. This is the third ‘handshake’.
b. The SATCOM responded normally and the SATCOM link was therefore available at this time.
17. 2141:24 – Log-On Interrogation by the Perth GES, with a response from the SATCOM
a. This is the fourth ‘handshake’.
b. The SATCOM responded normally and the SATCOM link was therefore available at this time.
18. 2241:19 – Log-On Interrogation by the Perth GES, with a response from the SATCOM
a. This is the fifth ‘handshake’.
b. The SATCOM responded normally and the SATCOM link was therefore available at this time.
19. 2313:58 - Ground to Air Telephony Call Placed from a number with country code 60
a. Q10 AOC Priority Level.
b. This call would have been routed to the cockpit and should have resulted in a chime and an incoming visual annunciation on the Audio Control Panels, and, if the appropriate SATCOM page was selected, then also on one or more MCDU.
c. The GES logs show zero duration, indicating that the call went unanswered. Note that there are two methods for the answering of an incoming call: Either by pressing the relevant Line Select Key on an MCDU, or by keying a microphone.
20. 2315:02 - The GES logs show that the unanswered Ground to Air telephony call was cleared by the calling party.
21. 0010:58 - Log-On Interrogation by the Perth GES, with a response from the SATCOM
a. This is the sixth ‘handshake’.
b. The SATCOM responded normally and the SATCOM link was therefore available at this time.
22. 0019:29 - SATCOM Log-On, initiated from the aircraft terminal. This is the seventh ‘handshake’.
23. 0019:37 - SATCOM Log-On, successfully completed
a. The SATCOM link becomes available (for voice and data – Class 3) once more and normal SATCOM operation resumes.
b. No Flight ID was sent to the GES during the Log-On.
c. The GES recorded an abnormal frequency offset for the SATCOM Log-On Request and Acknowledge transmissions.
d. The IFE did not subsequently establish the two Data-3 X.25 connections over the SATCOM.
e. Note that this is the last transmission received from the aircraft terminal.
24. 0115:56 - Log-On Interrogation by the Perth GES, with no response from the SATCOM
a. The SATCOM Link was lost at sometime between 0019:37 and 0115:56.
b. There is no evidence of a cockpit-initiated manual Log-Off of the SATCOM.
25. 01:16:06 – Log-On Interrogation by the Perth GES, with no response from the SATCOM
26. 01:16:15 – Log-On Interrogation by the Perth GES, with no response from the SATCOM
Source: Malaysian ICAO Annex 13 Safety Investigation Team for MH370, 8 March 2015, Factual Information MH370/01/15
The Factual Information was updated in 2018 by the Safety Investigation Report MH370/01/2018 which added new content but did not include all of the previous data.