I have thousands or hours on 737s and have trained on all variants up to the -800.
This event looks totally unrelated to any normal or non-normal situation that has been seen before.
An engine fire does not bring down a plane. An engine failure same. Even double engine failure leaves a 737 flyable via manual reversion - the only type in the world that can still do that.
The icing scenario does not fit either. This plane seems to have exploded in mid air prior to impact looking at the vast debris field with burning parts over a large area. The video of what looks like a Concorde last moments is graphic , if true.
Sherlock Holmes said "eliminate the impossible and your are left with the probable"
So what is left?
It is going to be hard since the authorities in Iran are going to have all the evidence and can release what then wish people to think. I believe that even a regime like the one that exists there will have to apply ICAO protocols to the investigation but it will be like pulling teeth.
The one truth that I still believe in here is that the 737 is still one of the best and safest planes every built and this event alas adds fuel to the fire of the narrative that Boeing is bad for you.
Condolences to all aboard. Very sad indeed
Old Timer
Over.....