Originally Posted by
Uplinker
The THS is not "hidden"; the trim wheels either side of the thrust lever quadrant clearly show any THS movement. Auto trim would not be a surprise to a properly trained Airbus FBW pilot.
Mechanically coupled side-sticks would need to have joints, bearings, levers etc, and would require a mechanism to uncouple the sticks, all of which could jam and cause more problems than it might solve.
Hence, if the side-stick position indication display - see below - that we use to check our controls before take-off were to reappear on both PFDs in the event of a stick being held at or near a limit in flight, then both pilots - and a third pilot - would be able to see on both PFDs what was happening. It would only take a couple of lines of extra program code in the software to add this feature.
I think there is something inconsistent in what you're saying.
You're saying that the THS is not hidden, and that the trim wheels clearly show any THS movement.
But at the same time you say that the opposite sidestick is not visible enough.
In fact, the opposite sidestick is approximately as visible as the trim wheel, if not a bit more. It is in the peripheral vision, not in the primary or secondary visual circuit.
So I don't see why you would oppose making the THS more visible, while advocating for making the sidestick more visible.
I understand even less when considering that pitch control is achieved with both THS and elevators, trim wheel and sidestick.
Originally Posted by
Uplinker
Airbus FBW is a very good design and well engineered product - an order of magnitude better than what existed before its introduction. Nothing can ever be completely fool proof however, which is why the authorities rightly demand ATPL licences and type ratings - to ensure that aircraft are flown by capable professionals, not fools.
Reality is a bit different.
Airbus design directly contradicted the usual rules that existed before. And uncommanded THS movement is directly involved in this.
Aircraft are supposed to have a positive longitudinal static stability. Airbus FBW does not behave like that, "thanks" to THS moving automatically.
It has been deemed acceptable only with protections, and when those fail, you have an aircraft that would not be certified, with no information to the pilot.
Originally Posted by
Goldenrivett
Would you call a B737-300 a normal aircraft? Would you think the crew of a B737 would recognise the pitch trim winding slowly backwards with the AP engaged on an ILS APP as the speed reduced? I suggest you read
B737 GA at Bournemouth
"During the go-around the aircraft pitched up excessively; flight crew attempts to reduce the aircraft’s pitch were largely ineffective. The aircraft reached a maximum pitch of 44º nose-up and the indicated airspeed reduced to 82 kt. The flight crew, however, were able to recover control of the aircraft and complete a subsequent approach and landing at Bournemouth without further incident. "
Crews need to be constantly alert and not become "passengers" by assuming their aircraft will perform flawlessly every time.
Well, with AP engaged the trim can do what it wants.
I never flew the B737, so I don't know how that one behaves, but I have a clear idea of what I would think ideal.
It would be ideal if the stick longitudinal position represented the total pitch moment. Fully back : everything is pulling fully up (THS and elevators), and vice versa.
So if your aircraft is slow, you feel it because your hand/arms are backwards. That is, if your airplane is an awkward position you will feel awkward too.
And the trim only purpose would be to set the zero force position.
If I recall correctly, light aircraft with an AP work like this, and you've never heard of a pilot who applied the right flying technique stall and crash in this type of aircraft (or if you did, it was because of other factors such as flying recklessly into conditions that they're not trained or equipped for). And they have much less yearly experience than airline pilots.
There is nothing 'dangerous back there' to a properly trained Airbus pilot. I think you have been very badly taught the Airbus and also your scan needs revising and improving. I think your problem is with your 'trainers' not with Airbus design.
I'm sorry but my airline uses the standard airbus TR. The trim wheel was never in the scan. The amount of manual flying in degraded situations is minimal, just read the latest syllabus to count how many minutes there are...
And if this type of unexpected THS behavior crashed at least 4 medium/large hulls (I'd have to look for others) then I don't see how you can deny that it's dangerous.
Did you imagine yourself for one second with the THS going unexpectly full up ?
Even if you noticed, did you imagine yourself pushing down the wheel ? How many turns would that be ? How much time would it take, with both hands ? What else could you be doing at the same time since you would have to look at the small numbers in the pedestal ?