In lighter aviation news. BA plane lands in Edinburgh instead of Dusseldorf by mistake - BBC News
Passengers board for Dusseldorf. Pilot has flight plan for Edinburgh! TBH I am suprised this doesn't happen more often.
Passengers board for Dusseldorf. Pilot has flight plan for Edinburgh! TBH I am suprised this doesn't happen more often.
It is interesting to me that the way to recover control of the 737 Max from the auto-pilot is radically different from its predecessors.
In previous 737 models, the pilot has an autopilot disengage switch on his control column and once pressed the autopilot disengages completely. The plane is under manual control.
In the 737 Max, the button on the column does not fully disengage the auto-pilot but instead leaves the MCAS in control of the stabilizer. There seem to be only two ways for the pilot to disengage the MCAS: switch off the electricity to the stabilizer motors completely via two buttons on the control panel or extend the flaps (MCAS is not supposed to engage unless the flaps are fully retracted).
Importantly: if you switch off the stabilizer motor you can only change the trim by manually rotating the trim wheels. You lose the ability to change the trim under motor assistance from the control column switches. The trim wheels are geared very low and are physically hard to move. That means it takes much more time and effort to change the trim manually than it does when using the column switches under motor assist.
I have seen no mention anywhere of extending the flaps as a recovery method for disabling MCAS even though this would maintain the trim motor assist.
Is it the case that the MCAS recovery procedure simply borrows the old 737 procedure for dealing with a "trim runaway" failure? This would be caused by the stabilizer motor running without being commanded by either the pilot or autopilot. Presumably due to some electrical cable fault or column switch failure. MCAS adds an additional, much more likely failure mode, and always causes the nose to pitch down.
I was intrigued to learn that the stabilizer design of the 737 is such that when the trim is set to full nose down, the pilot cannot counteract it by pulling the control column right back, which controls the elevators. Thus once the stabilizer has been moved by MCAS the only recovery is to reposition the stabilizer. But the fact that the recovery procedure for MCAS (the same as for a trim runaway fault) tells the pilot to disable the stabilizer motor makes it very time consuming and physically difficult to correct it.
So, even if the only system failure was the AOA sensor, the fact that the pilot is not told how to disable MCAS without also disabling the stabilizer motor servo makes the recovery very much harder and slower. The presumption that the extreme action of completely disabling the stabilizer motor (intended for a trim runaway fault) is competent for an MCAS fault during the first minutes of take-off seems ill-conceived to me.
In previous 737 models, the pilot has an autopilot disengage switch on his control column and once pressed the autopilot disengages completely. The plane is under manual control.
In the 737 Max, the button on the column does not fully disengage the auto-pilot but instead leaves the MCAS in control of the stabilizer. There seem to be only two ways for the pilot to disengage the MCAS: switch off the electricity to the stabilizer motors completely via two buttons on the control panel or extend the flaps (MCAS is not supposed to engage unless the flaps are fully retracted).
Importantly: if you switch off the stabilizer motor you can only change the trim by manually rotating the trim wheels. You lose the ability to change the trim under motor assistance from the control column switches. The trim wheels are geared very low and are physically hard to move. That means it takes much more time and effort to change the trim manually than it does when using the column switches under motor assist.
I have seen no mention anywhere of extending the flaps as a recovery method for disabling MCAS even though this would maintain the trim motor assist.
Is it the case that the MCAS recovery procedure simply borrows the old 737 procedure for dealing with a "trim runaway" failure? This would be caused by the stabilizer motor running without being commanded by either the pilot or autopilot. Presumably due to some electrical cable fault or column switch failure. MCAS adds an additional, much more likely failure mode, and always causes the nose to pitch down.
I was intrigued to learn that the stabilizer design of the 737 is such that when the trim is set to full nose down, the pilot cannot counteract it by pulling the control column right back, which controls the elevators. Thus once the stabilizer has been moved by MCAS the only recovery is to reposition the stabilizer. But the fact that the recovery procedure for MCAS (the same as for a trim runaway fault) tells the pilot to disable the stabilizer motor makes it very time consuming and physically difficult to correct it.
So, even if the only system failure was the AOA sensor, the fact that the pilot is not told how to disable MCAS without also disabling the stabilizer motor servo makes the recovery very much harder and slower. The presumption that the extreme action of completely disabling the stabilizer motor (intended for a trim runaway fault) is competent for an MCAS fault during the first minutes of take-off seems ill-conceived to me.
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Given the elevator is a comparatively tiny flap on the back of the stabliser that is not really suprising.
In short,
The 737 Max introduces a new failure mode due to engine size and placement that can cause stalling during take-off.
The remedy was to add MCAS to prevent stalling. This introduces a second failure mode when the AOA sensor is wrong and causes MCAS to fly the plane into the ground.
The official remedy for an MCAS failure is to use the existing trim runaway procedure that switches off the stabilizer motor (needlessly) thus making recovery a lot harder and very hazardous when the plane is so near to the ground after take-off.
The 737 Max introduces a new failure mode due to engine size and placement that can cause stalling during take-off.
The remedy was to add MCAS to prevent stalling. This introduces a second failure mode when the AOA sensor is wrong and causes MCAS to fly the plane into the ground.
The official remedy for an MCAS failure is to use the existing trim runaway procedure that switches off the stabilizer motor (needlessly) thus making recovery a lot harder and very hazardous when the plane is so near to the ground after take-off.
Don't forget that according to Airline pilots prior to the Lion Air crash they were not told that MCAS exists and training for the 737 MAX consisted of playing on an ipad for less than an hour.
All the info that has come out points firmly into the direction of Boeing being at fault and none towards other issues. The planes were practically new so maintenance should be out, the Lion Air plane had a new sensor fitted before the flight.
Human error is hard to conceive since Boeing basically told pilots that the MAX flies exactly like any other 737.
I suppose we will know more once the official reports are published.
All the info that has come out points firmly into the direction of Boeing being at fault and none towards other issues. The planes were practically new so maintenance should be out, the Lion Air plane had a new sensor fitted before the flight.
Human error is hard to conceive since Boeing basically told pilots that the MAX flies exactly like any other 737.
I suppose we will know more once the official reports are published.
The pilots were saying that now the computer can over ride the pilot whereas previously it was the other way around.
This is fine if all the sensors are working ok but if something goes wrong then its the old computer adage of "garbage in, garbage out".
Wife and I went to Paris for s short break in a January via Eurostar. On the way back, 20 mins out of Garde du Nord. we are cruising along, and suddenly the train stops and we are stuck for about 10 mins before the announcement ‘ ladies and gentlemen . . . We are on the wrong track’
At least they caught it in time LOL
I am pretty sure that the plane would gain more than enough altitude to make it difficult to see what side of the road the traffic is on pretty quickly. Try google earth at 5000 feet eye level and remember what rate of climb a plane achieves in normal flight out of an airport. The viewing angle to the ground is also not that good from a passenger seat anyway.
I tried google earth over a housing estate that can be recognized from the air and it would be pretty difficult to spot the direction of the traffic from 1000M or about 3000 feet. I did not put a link up because it will not work in some browsers. You would have to be on the look out for something pretty big on the ground that you have also seen from google maps setellite so that when you see it from a plane you will know where you are.
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