With the retrieval of the black boxes we should know soon enough what happened. It will be interesting to see if the stall warning was activated but for the time being I'll just ask questions to the pilots that fly the 600 and to those who know the airport of departure.
First… To those who know this airport. Do we know if one of the SIDs at this airport requires a right turn after departure?
Flight tracking shows a right turn followed by a left turn and then back to the right where the aircraft is almost on runway ending but off its centre axis. To me this seems they were struggling to control the aircraft.
Second… To ATR 600 pilots. What is the Vmca of this aircraft? What is the Stalling speed of this aircraft assuming a normal fuel load and pax load (58 + crew) to make this flight to destination? Assuming we can come close to its GTOW figures, we can probably figure out the takeoff speeds, a clean stall speed and one with flaps at takeoff position.
Weather was basically VFR with some rain and IIRC the winds on the ground were 10-15kts.
Now for the speculation part…
We know from the flight tracker that the aircraft reached about 1300 feet. The highest speed attained was 116kts, the lowest was 81kts and in its final stage prior to impact was increasing slightly to show a recorded speed of 85kts.
Now these speed are most likely ground speeds so if we take a 10kts headwind component we can assume the IAS would have been 126kts, 91kts and 95kts. Now assuming those IAS speeds are correct are we close to a stalling speed for flap 0 or flap in takeoff position for an ATR 600 for a given weight at takeoff?
We know one of the pilots called the “mayday and engine flame out” so we can almost ascertain there was an engine failure and most likely the left one. Why the left one? Because of the pictures showing us it was feathered or almost feathered, but definitely had a different pitch angle on its blades versus the right engine’s blades and finally it was turning slower than the right engine.
I think there is the possibility that the left hard over was a Vmca departure, a stall or a combination of both. From the video we see the aircraft seems to be level and descending then the left roll occurs.
Was this just a stall or a Vmca departure?
Perhaps has they were “gliding” towards the open area beyond the elevated highway, the pilots knew they were not going to clear it and added power to the one engine producing power, the right engine (on the pictures we see this because the prop is rotating faster).
At that moment perhaps they were close to Vmca and as the power came up there was not enough authority on the controls to keep it level and the aircraft rolled left.
This is just an exercise and is all speculative on my part… I’m not blaming anyone or pointing the figure at anyone, it is merely here for discussion purposes…
Now for your thoughts and view point and please keep it civilized!
In regards to the left hand engine and its propeller, if indeed this pictures shows that left engine it seems to me to be in a feathered position.
