Sorry, 777, we were on different flight paths! I was referring to the SURFACE debris field, where the narrow debris field at the Pentagon is a fair comparison. Your points on the ocean floor debris field are well made, with respect. Water not being compressible a high-speed ocean impact mimics a high-speed building impact. The Pentagon is a solid building, but not much more solid than the ocean surface if you hit it doing 500 knots.
Dutchy: the angle of descent of a shot-down aircraft can be affected by a number of factors. With MH17 the most important was probably the loss of the nose section, which from memory broke away fairly early. This affects the aerodynamics, very obviously, although please don't try it at home.
I suspect that MH17 had power for longer than MH370 - the mere fact that the pilots have been murdered and the cockpit flight controls shot away does not mean that the engines will go to flight idle, although most do. They may remain at their last commanded power setting, at least for some time.
Fuel supply is another factor. The fuel supply to the engines does not appear to have been affected by either missile impact. The AAM was aimed at the upper port cockpit area of MH17, well away from the engines and the fuel lines. The Chinese Buk appears to have detonated fairly close in, in semi-active homing mode. It was closer eg than the Phoenix which took down AF447. Neither engine on 17 appears to have sustained missile damage.
Damage to control surfaces, flight control avionics (the 777 is Fly-By-Wire) and hydraulics are also important factors, of course. 370 may have sustained critical control damage. We are talking different missiles of course - the Fakour-2 (modified Phoenix) has a 135lb warhead, the Chinese HQ-16 Buk 154. However the Fakour may have exploded closer in and may have taken out an engine and one or more hydraulics systems.
I would not be surprised if elevator control was lost in the case of 370, whereas we have a functioning elevator (from memory the 777 has an adjustable stabiliser and elevator rather than a stabilator) in the case of 17.
The two main differences affecting surface debris field as between MH370 and MH17 are the in-flight break-up sequence of 17 and its shallower descent angle.
There is no criticism of either crew. The crew of MH17 were murdered doing their duty before the plane crashed. It impacted the ground whilst out of control. Without specialist training,and with no obvious warning of a missile attack, neither attack was in practice survivable by civilian pilots.
One of my purposes in writing on this site, in Flypast and elsewhere is to make such attacks survivable in the future.
The critical things are to:
(1) exercise firm radar EMCON from the moment that radio and ACARS jamming is observed, in order to prevent or break missile lock. Remember that the incoming will have terminal radar guidance - you have no time to lose. Do not forget your radar altimeters.
(2) go to TOGA power and initiate an immediate powered descent to below FL100, vectoring away from the threat and towards the nearest land if over the ocean and you are facing a sub-launch.
(3) use ACARS, satellite phones or if in radio range cellphones to broadcast a Mayday message and squawk 7700.
(4) secure the cabin for evasive manoeuvring, warning the passengers that the aircraft is about to come under missile attack. Flight attendants should be seated by windows and in easy reach of telephones to warn the flight crew of incoming. Passengers with military backgrounds could be asked to assist.
(5) depressurise as soon as it is safe to do so, and no later than passing FL100.
(6) disregard the 250 knot speed level below FL100 and all airframe speed limits, maintaining manual control. Civilian autopilots are not designed for combat use. The aircraft should be pushed to the point where vibration levels suggests that structural failure is imminent. You are in a combat situation and the normal flight envelope no longer applies. Your first priority is to save your passengers - overstressing the airframe only becomes a major concern if it threatens structural break-up.
(7) Delay your evasive manoeuvres for as long as possible. Remember that the incoming is guided and you are trying to defeat its guidance system. You cannot outrun it, you can only out-turn it.
(8) Remember you have more fuel reserves than the incoming. It will only outrun you for as long as it has fuel. By the time you see it it may already have exhausted 50% of its fuel and
(9) Beware shrapnel damage if the warhead explodes within say 500 feet of your aircraft. An explosion within 150 feet is a hit, not a miss - remember it has a proximity fuse. If you cannot evade keep turning and present the least vulnerable section of the aircraft - the outer wings - to the blast. You will probably have inner ailerons and may retain some turning ability if you lose an outer aileron. What you do not want to lose are your passengers, your fin or rudder, you or your engines.