B-738 Crash in Russia Rostov-on-Don

[Aluminium shuffler]

For those speculating about autoflight ILS approaches and go arounds on the 737, they are normally flown single channel autopilot for Cat I and most companies only allow dual channel for Cat II/III or practice autolands. On disconnection of the single channel on Cat I, the autothrottle is also disconnected - manual control, manual thrust; Boeing insist on an all or nothing method on the 737, unlike their other types.

However, pressing TOGA while on a single channel app will give TOGA autothrottle while instantly disengaging the autopilot, putting the pilots in an unfamiliar position of having manual control but autothrottle. This is a big set up for one nasty mode reversion habit of the 737 (Classic and NG alike) - when the aircraft approaches its level off altitude, the AFDS goes from its current pitch mode (in this case TOGA) to Alt Aquire. As it does so, the MCP speed window opens at the current speed, not the FMC speed or previously set MCP airspeed. So, with the autothrottles engaged, it is very easy on the level off, especially if ROC was high, to have the engines throttle back to a commanded speed much, much less than the one previously set, possibly much less than the minimum speed for the flap setting (which may be being retracted post GA). This nasty mode reversion really sets you up for a stall just as workload is very high in a way that is not as easy to spot as it should be. This is compounded by the target airspeed airspeed being commanded in a two engine go around by the flap lever, the only time it is ever controlled by anything other than the MCP window or FMC, often causing a level of confusion. So, on each stage of flap retraction, the target speed jumps up a bit higher than the minimum speed for the selected flap, and eventually you see a target faster than clean speed. This flap lever speed selection is overridden by that Alt Aqu reversion, so unless you are watching the mode annunciations or see the speed bug jump, you probably won't know it happened. So, you have seen a safe speed selected, and then, all by it self, it drops by up to 40kts. Not good, especially in shear. It is a quirk that should be emphasised during training, but it doesn't seem to be.