From the English version of the prelim report;
The messages were at least five or six seconds apart, which can be explained by the limited rate of communication by satellite. There are two possible reasons for the longer gaps: either the aircraft did not have any messages to transmit, or it no longer had the means for doing so (loss of satellite communication performance, for example).
and
• the last message was transmitted to the aircraft at 2 h 14 min 28 s and was effectively received,
• the twenty-five messages transmitted by the aircraft were correctly received by the ground station,
• the gap observed between the message sent at 2 h 13 min 14 s and the one sent at 2 h 13 min 45 s is due, at least in part, to a temporary interruption in the communication link between the aircraft and the satellite,
• there were no satellite telephone communications during the flight.
It also clarifies that
17 The reception time given is that of the service provider’s server processor
The messages average six seconds between each one and this, as stated, reflects the timestamp applied at the SITA server, in other words the time received by the service provider, not the time generated. If you look at the first fifteen messages you'll note they were all generated in the 0210 window, so the cascade was progressing very rapidly.
There are then four messages generated at 0211 and one, the NAV ADR DISAGREE, generated at 0212. Then come the biggies, the PRIM1 and SEC1 faults generated at 0213. There follows a maintenance status message on ADR2 and the CABIN VERTICAL SPEED advisory followed by an uplink message to the aircraft, probably an ACK of the last advisory, which was "effectively received".
The report noted that four transmit cycles were missed from
2h 13min 14s and attributes that, in part, to the aforementioned "temporary interruption" in the satellite link. No mention here of lack of messages to transmit. The most likely causes for this stated interruption (IMHO) would be temporary loss of power to the transmitter or, more likely, the SATCOM antenna being outside of its operating envelope. However, it was back and capable of receiving and transmitting an ACK up until at least 2h 14min 30s (as stated above).
Questions to the ACARS pundits;
1. Why the drop off in message traffic after the 0210 window
2. What is the interpretation of the 0211/0212 sequence
3. At what point would you surmise the upset may have occured.
Rgds.
24V