I've been discussing with other people around here and as I have listened to a different version of the story, regardless if it is right or not, I thought I should point it out, even though it contradicts my previous post a little.
This version basically claims that:
- Legacy was cleared to remain on FL370 after BRS until TERES (where on their FPL they should've climbed to FL380)
- There was a comm failure near TERES, but the Legacy proceeded according to FAA Lost Comm procedures, remained on the last cleared FL (instead of following ICAO procedures of following FPL levels).
- As the Legacy set the XPDR to 7600, the XPDR went unnoticed to STBY (aparently it wasn't fixed by the
AD).
- There was a Lost Comm freq given by Brasilia, but that frequency was aparently copied wrong.
- After the MAC, Legacy pilots realized XPDR was on STBY and turned it on 7700.
This is by no means an official version. It's just a different version that I heard.
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Suposedly Contributing factors
- ALTN Comm freq being copied wrong;
- XPDR going to STBY after 7600 was set
- FAA Lost Comm procedure being executed instead of ICAO Standard (the later directs the lost comm aircraft to follow the FPL)