Don't become overly fixated on the "FLCH Trap" . I don't think it is as simple as blaming the "FLCH Trap" .
I suspect that the "FLCH Trap" is one of many things that are causal factors in the crash.
I think there are complex multiple causes and contributing factors to the crash.
Overall and most importantly I feel there is a cultural problem. While automation prevents a lot of accidents; it also introduces some dangers. I feel that automation is contributing to complacency and a lack of basic flying skills.
One way I put it is; pilots are letting the planes fly pilots, rather than the pilots flying the planes.
Allegedly according to flight data recorders, 8 seconds before the crash, the throttles were advanced. If I understand correctly one of the pilots advanced the throttles. If I understand correctly, this would have disengaged the autothrottle. Therefore from that point on I would think "FLCH" would be disengaged.
Allegedly according to flight data recorders, 7 seconds before the crash, a crewmember called out to increase speed.
I don't know how long it takes for these engines to spool up. But I would think 8 or 7 seconds would be enough time to get enough power to have prevented the crash.
I suspect that not enough power was added.
I was taught to largely land airplanes with my hands on the stick and throttle. I think the pilots in the crash were fixated on using attitude/pitch to control the flight path, thusly neglected/forgetting thrust.
I get the impression that many modern pilots have become addicted/dependant to the use of autothrottles and have become complacent with monitoring their speed and throttle. I get the impression that the airline industry often presses pilots into situations that encourage pilots to become auto throttle addicted/dependent. IE: Flying on the edge of flight envelopes to save fuel, time & money.
I get the impression that the *culture for landing large modern aircraft have fallen into the **routine of using hands the stick (yoke) only to land the planes. (As opposed to hands on stick and throttle landings)
*(pilots, airlines, governing agencies, and manufactures)
** (a trap of complacency and dependency).
CRM (Crew Resource Management) seems to have been lacking. Three pilots in the cockpit, yet the aircraft was allowed to get too slow and too low. An instructor with not much time on type of aircraft.
I think automation has increased aviation safety, however I think automation has inadvertently introduced some of its own dangers. There is no perfect solution.
If reasonably possible; training, systems and procedures should be revamped to try to prevent the "FLCH Trap".
More emphasis should be made on monitoring and maintaining the glide path, airspeed and descent rate during landing. (Basic flying skills) Policies should be improved to qualify, train and maintain these fundamental skills.
The above is just my personal opinion, with what little is known publicly.