In my opinion it will be highly interesting to see the actions of Air Traffic Control of Brasilia and Manaus and the communication between the two control centers indeed. In the light, that Brasil officials maintain, that Brasilia Center did try to contact the Legacy for 7 times (over a period of about one hour), but did not receive a reply, and at the same time states, that the transponder of the Legacy was off, what would have been sensible for ATC to do indeed, and what was ATC required to do? Should they leave it at that - and do nothing, trusting that the pilots would follow proper procedures? Or should they have done something?
From my point of view it would have been logical to block both FL360 (their flight planned level in case they followed loss of communication procedures) as well as FL370 (the last known level they were on and that they were cleared to, in case they didn't notice the loss of communication) for all other traffic. At the same time, with loss of voice communication and transponder signal, it would seem prudent to no longer assume RVSM, so at least separate aircraft by 2000 feet minimum, as has been suggested before in this thread already. That would mean, that the B737 could have been assigned to FL390 (if able) or to FL330, perhaps as an additional safety margin asking her to track parallel (and not on) the centerline of the airway at say 5 or 10 nm deviation.
Now add the picture, that the Legacy was seen turning, climbing and descending without clearance on radar, which led to the conclusion by officials, that the pilots had turned their transponder off to "show off the airplane to the new owners". Would that not set off all alarm bells with Air Traffic Controllers? Would that, in an unexpected loss of communication scenario, not trigger suspicions, that the airplane may be in an emergency and the pilots just not able to communicate (following the principle aviate, navigate, communicate), and invoke according ATC emergency procedures?
So this is why I have this hot burning question: what did Brasilia Center do indeed? Did they talk to Manaus and tell them, that there is a likelihood of an airplane approaching the intersection at (the wrong) FL370 or FL360, and then coordinate a level change for the oncoming B737? Did they indeed (attempt to) clear the airspace around the Legacy? What is the procedure for an air traffic controller, who cannot ascertain, that an airplane under his control approaches the boundaries of his sector at the correct altitudes/flight levels, that have been assigned for transferring the airplane into the responsibility of the next sector?
So far, the lack of any information on that topic as well as the facts, that the Boeing was still on flight level 370 (the last level the Legacy was known on too) and the collision occured close to the section boundary, seems to suggest, that there was no such coordination between the two centers. Such a coordination would however have broken this link in the chain to disaster.
Don't get me wrong here - if the Legacy crew indeed did turn off the transponder or did wrong as is being alleged, then they should face the consequences. The actions of ATC (or the lack thereof) may however well have contributed to the collision. Within that hour between the loss of communication and the collision ATC did have a significant chance to break one of the links in this chain to disaster. BTW, I am aware of the AD, which may also explain the loss of transponder signal, but would not explain why their CVR recorded the 7 attempts by Brasilia ATC to contact the airplane (which prompts me to be very suspicious regarding the Legacy crew, although there may be another technical reason not yet discussed, why the CVR could read Brasilia, but the crew would not - but that's not the purpose of my posting).
What's the implication, BTW, with the automatic descent or climb to flight level according to flight plan, if the airplane looses communication at quite some different flight level or perhaps altitude (e.g. cleared to FL120, flight plan at FL330)? Would that automatic climb/descend not create a lot of havoc and risk of midair collisions with planes on flight levels in between, especially in a busy airspace? While I might see, how air traffic control could handle such a scenario with working transponder signals by knowing exactly, what altitude the losscom airplane is at, without a working transponder and thus without knowing exactly what the losscom airplane is doing, that seems to be an impossible task, except clearing the entire airspace around that airplane ... Any insight?
Servus, Simon