Originally Posted by
Rananim
We MUST assume that :
a)the accident crew were aware of the previous flights UAS because it was written up in the tech log and would prohibit that Commanders acceptance of the
aircraft unless it had been signed off by a licensed engineer.When the accident Captain signs for the aircraft,he acknowledges reading the write up by the previous commander and the corrective action taken by the engineer.He must do this to accept the aircraft.
We CAN REASONABLY assume that:
a)The accident crew would have given special attention to UAS during the pre-flight briefing.They would have reviewed memory items and/or a plan of action.
b)The accident crew would have tried to obtain first hand information from the previous crew if possible(phone)
c)The flying spanner was added to the accident crew because of the tech issue.Lionair is a big airline and will have engineers based at most destinations.
d)The accident crew would have discussed the absolute need NOT to take a known pitot static anomaly into the air,of the need to abort the takeoff if ASIs diasgree at 80 knots.
e)The fact that they did not abort the takeoff implies strongly that the UAS was undiscoverable on takeoff.Prime suspect static vent(s).
We CAN HOPEFULLY assume:
a)Both accident crew members had been trained in UAS events in the simulator on one or more occasions in their flying career.
b)that both crew members knew verbatim the UAS memory items and of the absolute need to disengage ALL AUTOMATION and recognize that there is a mismatch between reality and perception and fly the plane using common sense attitude/thrust combinations.
c)That the crew would have sufficient lateral thinking to disengage any system fed by ADIRU false data that might conflict with their ability to control the aircraft.eg STS.The pilots see/hear the trim wheel spinning.They know or should know it is fed via AP stab trim motor.They know where the AP stab trim cutout switch is.
We can NEVER assume:
a)that the startle effect in all non normal situations will be controlled and handled well by a crew.The longer the startle effect lasts the more chance for loss of muscle memory,cognitive thinking,and onset of panic.
So what do you think that the crews intent was once the UAS issue surfaced. Were they focused on returning to the field (level at 5k vs, gradual climb?) or did they intend to continue the flight as per the previous crew. Given the time lapse (roughly 5 minutes) at roughly 5000 feet without declaring an emergency I'd guess that the crew felt reasonably in control
of the situation. If they intended to continue why not maintain a gradual ascent like the previous flight? If in fact they had flight control issues (vs strictly UAS) why not declare an emergency? Is it possible that the engineer was in the jump seat and making trouble shooting recommendations or observations/requests? Would this create a distraction or complication that would lead to a sudden loss of control?
If the crew had never had a 3rd person involved in a sim setting is it a possibility that the unexpected distraction of that additional voice and potential trouble shooting interaction created enough confusion to lead to a sudden upset or undertake a course of action outside of the preflight brief? I'm wondering if the tech might have asked them to reengage the AP at some point for example?