Turkish airliner crashes at Schiphol

[bobcat4]

Rainboe wrote:

Some people are drawing rather silly analogies with car cruise control. There is no similarity whatsoever. A lot of suggestions for 'improvements' are making the systems vastly more complicated. Boeing have designed it for simplicity within the requirements for autoflight. Even so, it is a hard area to master. I think they did a good job- it does what it says on the box! It relies on correct programming by the pilot and good observation.

You're right of course. But one thing strikes me as "weird". If A/T is on power idle, the pilot pushes the throttle levers to full power, and A/T then goes to power idle, then we would have a scenario where the pilot and the A/T disagree about the power setting. Pretty simple, isn't it?

Now, the question is: "Who should have authority in this case?". Forget this accident for a moment. In general, who should have authority, the pilot or the automation? (And yes, I know the pilot could disengage any automation if he like)

If the answer is "The pilot is always right and should always have authority over any automation". Well, then any automation should auto-disengage on pilot intervention. Doesn't that make sense?

It reminds me of a scenario where I was trying to reboot a Windows Server. The server wouldn't let me, for some strange reason. I had the authority to pull the power cord, and so I did. IMHO automation sould never question an operators (pilot) authority. The captain is in charge, not the electronics.

[ant1]

The intended result can be achieved by overriding the thrust levers by pushing them forward and keeping them there or disengaging the A/T and moving the TL forward.

[framer]

It reminds me of a scenario where I was trying to reboot a Windows Server.

LMAO!
Excellent.

[BOAC]

Jack - no, max power it is. The confusion arises over the term 'TOGA'. On the 737 there are buttons which select TOGA power. It is that this TOGA press does other things involving flight directors and the like and the manufacturer's recommendation is a manual setting of max power ('straight arm'), PNF adjusts as necessary, while PF wrestles with the machine, flying basic pitch attitudes. The flight directors will not give useful information for a stall recovery. Once that is complete, the F/D can be reprogrammed to your heart's content. On a 'standard' g/a, pressing the buttons is fine as the F/Ds will give the right commands. Max power applied at a lowlevel stall will, as you should see above, while recovering you from the stall, make the a/c a handful and will also produce a huge nose-up pitch.

Bobcat - it is fine as it is. I think having it 'give up' the moment you touch the levers would be a mistake. It would only have taken a momentary press of a button to get manual control. We also get quite a lot of 'sticky' throttle movement due to friction where the throttles do not respond finely to the A/T demands and such a function might interpret this as pilot 'interference'.

[armchairpilot94116]

Silly SLF question : What are the main things to watch out for if you go for max thrust in a stall. Shouldn't you retract gears and flaps ASAP or should you leave flaps and/or gear as they are and just watch out the nose doesnt rise too much and just let the power get you out? Just SLF here. I should think the main thing is to build speed and altitude ASAP?

p.s. edit: think BOAC may have just answered my Q about max thrust anyway.

[bobcat4]

jackharr wrote:

But it does strike me as bizarre that an aircraft can be certified if max (symmetrical) power cannot be used at ALL STAGES OF FLIGHT.

As a non professional pilot, even I know that max power cannot be used at all stages of flight. The fist thing I thought of was an emergency descent after pressurization failure. Come to think of it, any descent with full power would be bad. And not even when descending. With the immense amount of thrust available in these birds it's easy to overspeed. I would dare to say 100% power is very rarely used on a normal flight. Perhaps except at short runway take-off.

[BOAC]

Not sure I did, 94116! However, no configuration changes are made until you are safely climbing away under control, for at least 2 reasons:
1) Gear stays down in case you touch the ground in the recovery when it will absorb some of the impact (yes, I know about muddy AMS, but in general). There is more than enough power available.
2) Raising flap and gear:
a) is distracting - 100% concentration required from both crew on flying out of the stall
b) can cause further pitch trim changes

[deltayankee]

On my car, if I manually override the cruise control (i.e. put my foot on the throttle) the cruise control disengages until I manually reengage it.

This works fine in a car, but isn't really applicable in an aircraft. Having AP and AT that automatically disconnect on manual input might sound like a good idea but there is another factor maybe you don't consider. Suppose that someone accidentally nudges the yoke or a throttle and doesn't notice it? I can recall at least one CFIT incident where this happened and the aircraft flew gracefully into the ground while the crew were unaware that it was no longer on AP.

If you think about it the way it actually works is very sensible: if you make a manual control input it lets you do it, assuming there is some urgent need, but if you don't follow up by explicitly disengaging the automatics it assumes that you don't intend to continue manual control and gets back to automatic control.

Over at Boeing and Airbus there are thousands of experts who work full time on developing these systems. Some of the things they do might appear daft to outsiders, but often there is a reason for things working the way they do.

[theamrad]

MU3001A and BOAC, just for clarification,
I didn't mean to imply that I believe passenger comfort to be part of the criteria concerning A/T off - A/P on approach. Nor would I think of it in terms of convenience - except where we would take that to mean that A/T use allows us more 'freedom' to reprioritise monitoring - and also ease the workload.

with a justification for using A/T based on the perceived difficulty of qualified crews to manually coordinate speed/thrust with an autopilot flown approach

I wouldn't suggest A/T use for that reason at all - but who could deny A/P driven 'pitch hunting' because the FCC's have no A/T input if not coupled - esp with turbulence or gusts and trying to maintain a changing target thrust.
Personally - my point would be to stick to all on (coupled) or all off - in accordance with AFM, etc. Not just because I understand/believe Mr. B's design philosophy/architecture - but it also makes the most sense to me.

BOAC --

Firstly, it is easy to fly manual throttles on an autopilot coupled approach - it is just discouraged by operators. I do not agree with theamrad's statement. It requires more monitoring also but does not really adversely affect pax 'comfort'. The autothrottle takes away a lot of the effort but CANNOT be left alone without monitoring.

Also discouraged by Boeing. But actually I'm not sure what there is for you to disagree with me on here - I agree wholeheatedly with what you're saying here - if we accept that the passenger comfort part isn't really a consideration here.

[Graybeard]

Better a Fail Warn in View than a False Indication

I'll be posting a fairly thorough explanation of the Radio Altimeter within a few days. Meanwhile, consider this:

If a sensor, such as the radio altimeter, is giving you erroneous information, you have the option to disengage its circuit breaker. That way, your brain won't be trying to integrate erroneous, nonsensical data, and further bogus alerts will be silenced. . The automatics such as GPWS, autopilot and autothrottle won't be relying on false data, either. They will look to the backup sensor, if equipped.

If radio altitude errors persist, such as reported at THY, then the C check and corrosion control programs should be reviewed.

GB

[Smilin_Ed]

AoA Indicator?

I asked this question about the AirBus on the Perpignan thread and never got an answer. Now I'll ask it here. Is there no AoA indicator in the 737 cockpit?

It would seem to me that stall recovery would be best accomplished by flying a specific AoA rather than pitch. AoA would compensate for aircraft weight, power setting, and probably some other parameters.

[jackharr]

BOAC

Jack - no, max power it is. The confusion arises over the term 'TOGA'.

Ah, I'm understanding better. So TOGA is not simply "Take Off and Go Around" Power but implies all the others things as well such as Flight Director giving appropriate pitch attitude after take off? I honestly can't remember now after all these years just how we used the term TOGA in the 146

Application of TOGA with all the "add-ons" that implies, might be instinctive close to the ground but in some circumstances, such as stick shaker, is clearly not appropriate. "Firewalling" the throttles (no doubt, even more power than with TOGA) would be the correct response to a low level stall but it might not be what pilots would immediately think of.

I go back to when I instructed on the Varsity in the 1960s/early70s. We would practice stalls in the approach configuration. If I remember correctly, the drill was: Full Power - Flaps to intermediate position - when climb established, Gear up. Would seem to be a good drill for any aircraft.

It does seem that all this modern automation leads to the possibility of mindlessly obeying the "computers" and not thinking outside the box. I am not alone in making this point.

[Smilin_Ed]

RadAlt Problems Noted?

If a sensor, such as the radio altimeter, is giving you erroneous information, you have the option to disengage its circuit breaker.

I don't think anyone ever noticed the RadAlt problems on this or any of the previous eight flights. If they did, I don't think they reported it.

[jackharr]

bobcat4

Come to think of it, any descent with full power would be bad.

Of course you wouldn't do that. But what I meant is that it should be possible to use full power at any stage of flight without losing control.

[armchairpilot94116]

To deltayankee regarding car on cruise : Reminds me that when you have cruise on in your car set to say 75mph and you punch the gas pedal to pass and go past 75 and then you may want to drop speed below 75 as you tuck in behind that truck but the cruise keeps you at 75 and this could cause momentary confusion while you are watching out for traffic. Could it be that having half auto and half manual control of a moving vehicle leads to confusion if your attention is on something else? I guess more training would help in this regard. But it must be more complex when some systems are set to do certain things when you do something manually and you forget that it will do that.

IN Congonhas (and a few other similar incidents) the crew forgot to bring both TL to idle on touchdown (their minds were on other seemingly more pressing watch out factors ) and thus the machine ,by design didn't know they intended to come to a complete stop and didn't allow all its systems towards that end.

To BOAC thanks. What is your take on the Ci676 stall and non-recovery on Feb 16,1998 at CKS on an A300-600? Seems to me they didn't watch their speed on approach and got into a stall they shouldn't have and then fiddled with the configuration and went to max thrust but didn't watch the nose. One wing dropped and then confusion reigned all the way to the ground. A possibly faulty altimeter apparently got them 1000 feet too high on the glide slope and the subsequent go around was mis-handled? I take it that they should've left the configuration for the moment, BUILT SPEED and watch the nose to get out?

What lessons can be applied to this latest stall/crash?

AG RVS - The Crash of Flight CI676

Please scroll down in the link to the timeline. Thanks again.

[dimitris_lam]

@BOAC #1916

a) is distracting - 100% concentration required from both crew on flying out of the stall
b) can cause further pitch trim changes

Is it only distruction of the crew or insane loss of lift due to retraction of flaps? Lift keeps you aloft, thrust gives speed to produce the lift, no? If you are at stall speed in landing config and you retract flaps you fall out of the sky don't you?

[MU3001A]

BOAC: "it is easy to fly manual throttles on an autopilot coupled approach."

I figured as much, thanks for confirming from experience.

The equipment I fly does not incorporate A/T so perhaps I'm biased against from the git go, simply due to unfamiliarity. However it does seem to me that A/T adds a layer of complexity not present with the manual application of power. If this added complexity - at a level once removed from direct control - leads to increased safety under all operations where A/T use is permitted and even required, then all to the good. But are there not routine operations where the utility of A/T violates the KISS principle allowing the potential for introducing yet more holes in the cheese only to be exposed when least helpful to a successful conclusion of the flight?

I wonder also if in this instance the presence of a training captain and the imposition of a checking regime perhaps intimidated the handling pilot into continuing with the automation when under different circumstances he might have reverted to some level of manual control? Perhaps the CVR will enlighten us?

[ant1]

Deltayankee, if you nudge the yoke enough it will indeed disconnect the A/P. Not the same story with A/T though disconecting these by moving them can theoretically be achieved, under certain circumstances already posted, it has little or no practical use.

MU3001A, my perception is that introducing A/T it's not like adding more holes, as I see it, you remove some holes and introduce new ones in a different spot. The trick consists in introducing less holes, or in a better place than what you remove.

[protectthehornet]

automation masks poor flying skills

I think using automation is a way to lessen the skill levels required to perform in the cockpit.

I think that many manufacturers of airliners have tried to simpligy things so that piloting becomes more of a minor skill rather than a dedicated calling. Indeed, we see reductions of flying time at every level of flight.

Those pilots who once were highly skilled are becoming automated out of being good pilots.

SADly, at the time when you need the skills, they are now gone...whether it is stall avoidance or recovery.

Stall recovery is not that hard. Firewall power and minimize altitude loss while the plane accelerates. Certainly, the old method of stall recovery, pushing forward on the yoke works too...if there is enough altitude.

Much has been made of the nose up tendency with the application of power on the 737...anyone who has ever flown the plane knows about this and should be ready.

I blame the industry that wants to make skilled pilots something of a bygone era. Sad.

[dicks-airbus]

bobcat4:

But one thing strikes me as "weird". If A/T is on power idle, the pilot pushes the throttle levers to full power, and A/T then goes to power idle, then we would have a scenario where the pilot and the A/T disagree about the power setting. Pretty simple, isn't it?

Fully agree with bobcat4, normal "system" behavior would be to diengage the automatic setting when there is manual override applied. This seems not the case with the NG.

Could the plane have crashed because the captain just needed three arms? TL, stick and trim back the AP settings?

Perhaps he just did not trim back assuming that AT would disengage when TL are moved by hand? Still very hard case with the amount of hours he had. And too simple considering all the training...