Manually overriding autothrust
 

To quote from Airbus...

"Except in emergency situations, AP and A/THR must not be overridden manually."

Just curious whether this applies to any other types. I have seen it done for a few moments on Boeings.

Depends what mode you're in, but on a Boeing anything, feel free if Thrust is your Speed mode and the ATC isn't keeping up nicely...... Approach as an example

What pilot would not override an autopilot or autothrottle if it wasn't doing what he wanted. No competent company would ever say don't override it if neccessary. Not even Airbus.

Absolutely, but if it's Speed on Pitch, then I guess you would look at other solutions
I never flew a 'Bus, but the quote sounds otherwise very odd, yeah

Don't tell me Airbus actually said that. Maybe that is why AF 447 crashed. Nobody was allowed to hand fly. When the autopilot failed because of loss of IAS maybe they were not taught how to fly pitch and power because they would have to disconnect the autopilot. I know it disconnected by itself but it might have been confusing for them.

Can you please reference that statement.

Seems to me we violate that directive every time we're on final.

The Douglas/Boeing doesn't prohibit it and it's sound practice I believe on approach in blustery conditions, as it saves that sinking feeling when the speed washes off towards Vmin and the AT goes to warp power to prevent further speed loss. :8

As far as 'over-riding an AP' goes, I guess we don't do that on any type really ( I have been known to change modes though, or disconnect it at times)
The 'Bus is a little unusual tho and I've heard that you don't touch the controls with the AP in ....... But then, why would you want to?
ATs are a different story tho, obviously

I think the confusion is between "Over-ride" and "Disconnect". I don't think AB is saying don't disconnect or downgrade automation if it isn't delivering what is required- but don't OVER-RIDE that is, make manual inputs while the automation is still connected, unless it's a serious, time critical problem.

In a Boeing, the same would be true of the A/P, though there's no problem "Helping" the A/T a bit if it is slow correcting the speed.

Why not override an autopilot? I did whenever it wasn't doing what I wanted. I don't even care if the autopilot works so overriding it is no big deal. Hand flying is quite simple. We all did it.

Don't think it's wise to override an AP, Bubs.
AT, sure at times

Why is it not OK to override an AP? That kind of complacency and trust leads to accidents.

A few people here are getting confused between over -ride and disconnect.

My mistake, it was referring to a runaway situation or hardover.

I believe they mean in this situation to disconnect. Only override if disconnection is not possible and an emergency situation has been created due to the malfunction.

:ouch:

The AT should be left alone,dont push or pull the TL when the AT is engaged.
If the AT is bit sluggish then increase the command speed and it will react,once done,reset speed to required.
Now if your AT is not behaving as it should be,(read turkish),then disconnect the:mad: and fly manually.
This overriding,push pull with full automatics on damages the AT clutch and is bad practice.

At least on the Boeing I fly overriding the AP is a normal feature and will degrade its function to CWS. Our SOPs call for that in a few specific situations but it is not reserved for emergencies at all.

Overriding the AT is possible, that is why there is a clutch in the first place. But it is of course not good practice to fly the whole flight that way. However is good practice to manually override for short term speed deviations. Might be a good idea for example in mountain wave situations.

You mean disconnecting surely.:p

bubbers 44
Wizofoz is correct. There is a difference between overriding AP and disconnecting the AP. You cannot override the AP or ATHR in Airbus FBW. If you force the side stick the AP will disconnect anyway. But there is no restriction on taking over manually. That should be done with ID button on the stick. As the Thrust levers do not move and are static in CLB gate you cannot overide (overpower) them but you can control them manually. Airbus goden rule 2 "Use appropriate level of automation.means flying selected speed, disconnecting ATHR and using manual thrust or even flying manually if required. Rule4 "Take action if things do not go as expected" tells you to be proactive and make the aircraft do what is needed with or without automation.

One of the classic automatic monkey event I witnessed (n the simulator thank goodness), was a experienced Chinese captain who in the 737 rolled over nearly inverted on a coupled ILS after the AT clutch motor on one thrust lever failed while the thrust levers were at idle while slowing for flap and gear extension. As the airspeed came back to Vref+5 with landing flap, the other engine went to high thrust to maintain the selected approach speed while the idle engine stayed at idle.

Instead of disconnecting the AT system and using manual thrust on both engines, the captain thought the idle thrust engine was actually an engine failure! He called engine failure and directed his F/O to shut down the engine with the failed AT clutch motor. There was nothing wrong with the engine. The AP could not cope with the huge amount of crossed controls needed to maintain the coupled ILS on one engine and disengaged itself. At no time did the captain attempt to use rudder to correct the yaw. All the time both pilots had their hands on their knees impassively watching the 737 roll on its back and go in like a bomb. The simulator was then "frozen" to prevent further embarrassment and consequent loss of face.

Centaurus
This has happened in actual flight on China airlines 006 where crew failed to monitor the aircraft flight path during restart of failed no.4 engine. The disoriented crew let the aircraft go on the back and screaming dive loosing 30000ft in 2and a half minute. The pilot finally completed the barrol roll experiencing 5g was able to land safely.

Really?...... The last few posts make me shiver, for so many basic reasons it's not worth talking about

I guess that Airbus' just aren't tactile machinery ....that's all there is to it!

Boeings are very much so, tho..... even the Tripple is tactile for a FBW

Altcrznav..........you do understand now, Yeah?

A peculiar thing about this post is a question is asked about an Airbus procedure by a non Airbus pilot and also all the answers and conclusions are drawn by non Airbus people and finally ending up with favourite past time A vs B. I have flown both enjoyed both. I treated them as different concepts. I would not comment on something I don't know.

Explain the difference in an Airbus.

Making manual inputs while automation is still connected is not unusual nor abnormal. We have 4 levels of automation and, for example, changing heading to avoid a cell would simply be a change to the level of automation. Nothing is over-ridden and I don't ever remember seeing that referenced.

You don't over-ride anything but merely change levels. Level on is all automation off (occasionally final approach) and level 4 is fully automated (CRZ).

Alt,

Changing from, say, LNAV to HDG SEL to avoid a cell is neither disconnecting nor over-riding automation, it is simply changing mode, and as such is not a manual intervention.

Manual flight implies direct control input- i.e via the yolk in a Boeing, and that would NOT be a normal input while the A/P was still connected.

If a sudden, time critical intervention was required, disconnect and manual flight would be appropriate.

I understand that.

But this thread was started as a reference for Airbus which doesn't have an over-ride.

Why are we talking Boeing stuff?

Fair enough, I have little knowledge about Airbi- But if you CAN'T over-ride an Airbus A/P-A/T, why does the Airbus manual contain a statement to not DO so except in an emergency?

Golden Rules.... AIRBUS
 

From Airbus FCTM........

I THINK NO.6 answers the question.....

Could be applied to any modern aircraft really.

1.The aircraft can be flown like any other aircraft 2.Fly, navigate, communicate - in that order 3.One head up at all times 4.Cross check the accuracy of the FMS 5.Know your FMA at all times 6.When things don't go as expected - take over 7.Use the proper level of automation for the task 8.Practice task sharing and back-up each other

That's not over-riding the Airbus automation, its turning it off or changing to a different level of automation.

Again, you DO NOT over-ride Airbus automation. You downgrade it to a different level.

There used to be an airbus procedure that sugested momentarily pushing the thust levers above the climb detent if the autothrust was slow to correct an underspeed in approach. It is a technique that I have used (only rearly I may add) and it worked ok.

I can no longer find a reference for the procedure, has it been taken out?

I hope so because it'll get you into trouble.

Fifteen years on the Bus and I've never heard of that recommendation.

It applies to any classic controls, autopilot equipped type (e.g. A300 and 310). Don't fight the autopilot. Just don't.

For those who want to know more, IIRC back in late 1990ies Richard L Collins reported about experiment in which GA pilots were put in Malibu simulator and given "soft" AP failure with descent initiated in altitude hold. Quite a lot of them thought they can just pull a bit back on the yoke while keeping the AP engaged to return the aeroplane back to altitude and keep it there. Many of them were eventually simulated killed through dive into ground coming from extreme nose down trim introduced by AP. Interestingly, Nagoya A300 catastrophe was quite similar; pilot was fighting the pitchup with down elevator and still active AP fought it by trimming the stab up.

N/A for FBW Airbi. Attempt to override (introduce manual input through stick with AP engaged) will invariably lead to AP discon. Quote that started the thread is from general brand A operations note, dealing with their entire catalogue.

Provided hand is coupled to FCU, not to stick. That needs not be everyone's (or even majority's) definition of manual.

I don't understand your comment. Its superfluous.

If your hand is "coupled" to the stick and your making inputs, you're going to disconnect the autopilot.

You cannot make stick inputs with the AP on in the Airbus - period.

Then you probably never got the chance to read the Flight Crew Bulletins, part of the FCOM.

I think you're wright !
It appears such procedure is not mentioned anymore ... Airbus did not publicize much why they now think it is better not to mention it any longer ... ?

WIZOFOZ, Elephant and Castel, Altcrznav
Further to my Post#18
1. Override in A320 means disconnecting AP by forcing the side stick. Since it unusual way may be done in emergency.
2. Elephant and castle is right there was a procedure to push thrust levers slightly beyond CLB to get better response.
3. Atcrznav I am surprised you did not know it for 15 years. Anyway you need not know it now. Below is from FCOM Flight Crew bulletins.

Ident.:FCB-FCB24-00013125.0001001 / 31 MAR 11

Applicable to: ALL

REASON FOR ISSUE

During the approach, with the A/THR active, Airbus recommended to set the thrust levers above the CL detent (but below the MCT detent), in exceptional circumstances, if the speed significantly dropped below VAPP. However this procedure is not trained and proved to have more drawbacks than advantages. Therefore, Airbus no longer recommends to use this procedure. The procedure is deleted from the operational documentation.
If the A/THR performance is not satisfactory, the flight crew should take over,and control the thrust manually.

That's another odd (rather stupid) procedure. Why would you risk jamming the sidestick with enough force to overcome the lock and risk putting the aircraft in an inadvertent attitude when you have an ICO right there?

Unusual is a mild way to describe that technique to say the least.

I don't have an FCOM in from of my as my company has its own manuals for training, but does Airbus use the term "override" and "autopilot" together or does it use "disconnect"?


Its quite obvious from the bulletin that it was a crappy procedure and the key there is the it was not trained. My company never adopted it and it was never brought up. I've asked other Airbus drivers about this on our pilot board and none have ever heard of this either - some with many more years than I in the Bus.

You CAN override the autopilot on the Airbus, (but you shouldn't).

If you move the rudder pedals or the side stick with the autopilot engaged, the autopilot will disconnect.

The side stick is locked in neutral when the autopilot is on, but you can move it with enough force, at which point, as I say, the autopilot will disconnect. I suppose this allows an emergency reaction from a pilot given something really sudden and bad, such as a potential collision?

We used to be allowed to "Phase advance" the thrust levers by pushing them just out of the CLB gate and straight back into the gate again to increase revs on approach if the autothrust was being lazy, but this now has been outlawed. (I personally thought it was a very useful procedure, but a lot of pilots obviously misunderstood it and left the levers forward of the CLB gate for too long (i.e. more than a second, and ended up overspeeding).

All other actions, as others have said, are mode changes.

(sorry Alt - think we crossed there)

For me it was not needed often but very ocassionally it was quite useful. It was not trained? Not sure what is there to train. If the autothrust is not reacting to a slow speed in approach you move the levers just forward of the climb gate and back into the gate. That wakes the autothrust up so to speak. Hardly rocket science. Crappy procedure? How do you know, presumably you have never tried it.

AB now recomends disconnecting the autothrust all together if it is not performing. Fine, but this also involves overiding the automation momentarily to match the thrust lever position to the current thrust before pressing the disconnect button. Otherwise you end up with a sudden rush of climb thrust until you retard the levers.

Altcrznav
Jammed stab's quote I have not seen yet but was explaining the implications in Airbus FBW.
As you are aware you cannot override/overpower AP in Airbus it will disengage. There are three ways you can disconnect the AP only one is recommended i.e. ID button, the other two are from FCU and forcing the side stick which are not normal ways. The only emergency situation I can foresee is when you quickly want to take over to change the flight path and the ID button doesn't work then may be you force the side stick. The FCB in question crappy or otherwise was Airbus recommended procedure. Here we are not discussing your company procedures. ATHR disconnect procedure is part of training syllabus while this procedure was not and few pilots obviously have messed up approaches may be by leaving THR LVR in MCT. So now Airbus recommends disconnecting ATHR and use manual thrust instead. If you mess this up you are responsible since you were taught how to. The procedure was useful if you needed quick thrust response.

It could be argued the above comment is in contradiction to the flight technique for severe turbulence.

The B737 Supplementary Procedures recommends the autopilot be set to CWS mode. The pilot then is required to manually "fly" the aircraft through the CWS mode. Control forces are slightly higher than in no automatic flight, which in turn decreases the potential for over-controlling in gusts. This is especially important at high altitude where rapid use of aileron causes spoiler actuation and the scene is set for over-controlling by the pilot.