There are 2 noteworthy occurrences in the ATC radio transcript within just minutes of a 3rd noteworthy, quite unprecedented occurrence in aviation history:
- At 01:07:55 MH370 unnecessarily reported maintaining FL350 a second time
At 01:19:29 MH370 famously only replied "Good Night, Malaysian 370" without reading back the frequency for the handover, although this is an ATC instruction that should be repeated (see below)
At 01:20:33 MH370 "goes dark" (losing XPNDR, ACARS and SDU).
This temporal proximity caught my attention and left me wondering if the 2 ATC transmissions cited above are out of the ordinary (and thus a possible precursor of what was to come).
What are some important things controllers usually expect you to read back?
• Clearances: headings, vectors, altitudes, transponder codes, and radio frequencies. (a288)
« The last radio transmission “Good Night Malaysian Three Seven Zero” was spoken by the PIC. However, he did not readback the assigned frequency, which was inconsistent with radio-telephony procedures. » (safety investigation report, p.431)
Please cite what (if any) ATC rules have not been followed.
From your experience as flight controllers or pilots, how unusual is that ? Is this rather unheard of or occurring fairly regularly ?
Is the handoff procedure described below by the 767 Captain technically correct and does the missing step 3 permit the conclusion that step 2 was not executed either ?
@Edward_767, a 767 captain, has closely studied the audio recordings of the MH370 radio transmissions. He is convinced that the second altitude call at 01:07:55 was NOT made by the Captain, but by the First Officer, possibly because the captain was not in the cockpit at that time. His theory is that the first officer made the call because he was not sure whether the captain had made the previous altitude call at 01:01:14.
He makes another interesting observation regarding the final exchange where MH370 is handed off to HCM. He states that the typical radio procedure would be to
- receive the new frequency (in this case, 120.9 MHz)
- dial it into the radio as the standby frequency
- read back what frequency was dialed in as part of the confirmation of the handoff
- listen for the final transmission
- hit the radio switch which swaps the active and standby frequencies
- and call ATC on the new frequency.
In the transmission that acknowledged the handoff to HCM, the captain did not read back the frequency. Ed believes this is because the new frequency was never dialed into the radio, as the captain never anticipated making a call to HCM ATC. Ed believes the missing frequency during the acknowledgement of the handoff is yet another red flag.
The time between the 2 transmissions would be less than 15 seconds. It was 13 seconds at MH370’s previous controller handoff, where the new frequency was read back. At the handoff between Kuala Lumpur and Ho Chi Minh, the pilot acknowledged the handoff, but never read back the new frequency, and the call to Ho Chi Minh was not made. That leaves a window of only about 15 seconds for the abnormal event that caused the turn back.
ATC transmission log (full transcript incl. taxiing here)