Originally Posted by
MsCaptain
emjanssen: How do they know the FO started the descent without data from the FDR?
This is one thing that is troubling me as well.
This conclusion can reasonably be made by cross matching the timestamps of the ADB mode-s "selected altitude" messages with the timing of the sounds of someone pushing FMC buttons on the CVR.
09:30:52Z.386 MCP/FMC ALT: 38000 ft QNH: 1006.0 hPa
09:30:52Z.567 T,3c6618,43.122208,5.676482,38000,GWI18G
09:30:53Z.036 T,3c6618,43.122894,5.676993,38000,GWI18G
09:30:53Z.546 T,3c6618,43.124271,5.678166,38000,GWI18G
09:30:54Z.083 MCP/FMC ALT: 13008 ft QNH: 1006.0 hPa
09:30:54Z.096 T,3c6618,43.125295,5.678689,38000,GWI18G
09:30:54Z.676 T,3c6618,43.125961,5.679421,38000,GWI18G
09:30:55Z.156 T,3c6618,43.127157,5.680259,38000,GWI18G
09:30:55Z.397 MCP/FMC ALT: 96 ft QNH: 1006.0 hPa