A319 Overspeed Recovery

[Sean Dell]

This requires use of full speedbrake with the Autopilot on.
Has anyone tried this in anger (be honest)?
Did you use FULL speed brake as per the Airbus drill?
How quickly did the full speedbrakes retract when you were below MMO ?

Thanks for any info.

[SetStandard]

Seems like this is now the advice given by Airbus on the A318/319/320/321 in case of an overspeed.

We did it in the sim a few weeks ago; from stowing the speedbrake leaver, it was 27 seconds till the flight control page on the ECAM showed they had fully retracted. :ooh:

[Sean Dell]

Thanks for the reply Set Standard.
Seems like the procedure could take you from one end of the scale to the other.
Obviously with the AP in on the 320 you will only get half deflection, but nevertheless..... Seems a bit extreme :confused:

[WhyByFlier]

Bare in mind that half deflection on the 320 is equivalent to full deflection on the 319 (except for the extra 5 degrees on spoiler 2 when not in conf 3).


I've had a real positive windshear at 39000' over Paris - we went from a 40 kt tailwind to a 20 kt in a couple of seconds whilst flying at M0.78. The most effective, safest initial action is to pull speed and select it back (this changes the thrust mode and ATHR is far more responsive. Then we slowly used some speed brakes. We didn't overspeed! In FCTM take note it says if the trend arrow reaches or slightly exceeds Vmo/Mmo then go speedbrakes and THEN selected speed. It goes on to say if it significantly exceeds Vmo or Mmo i.e. it's happened - pull speed and select lower, consider AP disconnect and use speedbrakes with care considering the pitch up moment whilst close to the ceiling.

Ultimately, do use speed brakes but do so with care - bring them out slowly. Move through the flightdeck like it's filled with treacle!

[4468]

It goes on to say if it significantly exceeds Vmo or Mmo i.e. it's happened - pull speed and select lower, consider AP disconnect and use speedbrakes with care considering the pitch up moment whilst close to the ceiling.

In typical Franglais, I strongly suspect this is meant to inform you that the AP WILL ALREADY HAVE disconnected automatically, and you will already be experiencing a 'pitch up moment while close to the ceiling'?

So it's up to you to push the stick forward!

[Sean Dell]

Thanks for your thoughts chaps.

I am of course in agreement with you regarding the Overspeed Prevention drill.
However, this as you describe above suggests consideration of using the speed brake as required.

The Overspeed recovery is very specific in that it states that as soon as speed exceeds Mmo you use full speed brake. I just think its badly written and at least needs some italicised information to ensure the SB is used carefully and slowly.

[lexxie747]

Forget about the overspeed, that will never happen, now , the underspeed, how can we fix that?

[exeng]

[QUOTE
I've had a real positive windshear at 39000' over Paris - we went from a 40 kt tailwind to a 20 kt in a couple of seconds whilst flying at M0.78. The most effective, safest initial action is to pull speed and select it back (this changes the thrust mode and ATHR is far more responsive. Then we slowly used some speed brakes. We didn't overspeed! In FCTM take note it says if the trend arrow reaches or slightly exceeds Vmo/Mmo then go speedbrakes and THEN selected speed. It goes on to say if it significantly exceeds Vmo or Mmo i.e. it's happened - pull speed and select lower, consider AP disconnect and use speedbrakes with care considering the pitch up moment whilst close to the ceiling[/QUOTE]

Only flew the bus for two years and had one over speed in a similar situation to the above. Having flown Boeing's for quite a few years before the bus I treated the bus as if it was an aircraft that wasn't performing as programmed into the FMGC. I immediately disconnected the A/P, reduced the thrust manually, and gently pulled the nose up - and 'hey ho' we were out of the over speed condition almost immediately. In a serious over speed I would use the speed brakes.

Why you would continue to use use the automatics in a degraded mode such as 'selected speed' is quite beyond me. Airbus kindly provided you with a side stick so use it.

[4468]

exeng

If it was a 'proper' over speed, you didn't need to disconnect the AP. The a/c kindly does that for you! If you 'gently pulled the nose up', you were simply doubling up on what the a/c was already doing! So be VERY careful!

This is a FBW a/c with protections, not a 737!
Airbus kindly provided you with a side stick so use it.
As I explained. The AP will have disconnected, so what choice do you have???

At the end of the day, an overspeed is not ideal, but it's little more than a paperwork exercise. So don't stall, zoom climb, or pull the wings off the thing, and even if it takes a few seconds, she'll be right!

Edited to add: if you're planning to use full speed brake at FL390 etc I would polish up your 'Mayday' calls! Particularly if you think you might close the thrust levers too!!

[WhyByFlier]

In typical Franglais, I strongly suspect this is meant to inform you that the AP WILL ALREADY HAVE disconnected automatically, and you will already be experiencing a 'pitch up moment while close to the ceiling'?


Yes sorry, that was what I meant - I did an 'informal' quote because I don't have FCOM on my desktop which I was on at the time! The AP will disconnect with a severe overspeed and this is what they are pointing to I believe.

Only flew the bus for two years and had one over speed in a similar situation to the above. Having flown Boeing's for quite a few years before the bus I treated the bus as if it was an aircraft that wasn't performing as programmed into the FMGC. I immediately disconnected the A/P, reduced the thrust manually, and gently pulled the nose up - and 'hey ho' we were out of the over speed condition almost immediately

Yup, the A320 is extremely passive in it's response to most things when in soft alt mode. It's my experience that you should go selected (preferably at this level) or AP off to get it to start thinking again - it's quite happy to sit there at target speed + X knots at FL390 a couple of millimetres from Mmo whilst doing very little about the thrust.

The Overspeed recovery is very specific in that it states that as soon as speed exceeds Mmo you use full speed brake. I just think its badly written and at least needs some italicised information to ensure the SB is used carefully and slowly.


The thing is I believe that the FCOM overspeed recovery, though not stipulated, is with regards to a descent or low level. In that case I'd follow it strictly - speed brakes full would be my first response. However If you're in the cruise above FL330 and an overspeed occurs - immediately banging out FULL speed brake may well stick you into coffin corner if you're at a high enough weight. I'm not certain on this as I've never seen it and until someone shows me it at FL390, 60 tonnes I'm reluctant to try it. Even if it didn't put you into coffin corner, I don't trust the pitch mode of the A320 and THR mode of the ATHR enough to believe it wont leave you low on energy out of the overspeed - fine if the AP is off but if I don't have to hand fly at a high FL then I won't.

It's an interesting topic and your question is one I've benefitted from - for a definitive answer that you can produce in a court room I'd recommend asking your company technical pilot via e mail and getting a response from her or him in writing. It's the only way you'll cover your back should mother nature deal you a rough hand and there's some day time TV watching, injury lawyers for you type in the back who wishes to sue you for them banging their head on the locker!

[Sean Dell]

Guys, thanks for some well reasoned words. As ever, it just goes to show the never ending struggle to read between the lines and arrive at conclusions via inference.

plus ça change, plus c'est la même chose. The Airbus way....

[Check Airman]

I've had a real positive windshear at 39000' over Paris - we went from a 40 kt tailwind to a 20 kt in a couple of seconds whilst flying at M0.78. The most effective, safest initial action is to pull speed and select it back (this changes the thrust mode and ATHR is far more responsive. Then we slowly used some speed brakes. We didn't overspeed!

Not an Airbus pilot (my airplane doesn't even have A/T), but why wouldn't you just reduce power manually? Not criticising your action, as I'm not in a position to do so, but genuinely curious.

[WhyByFlier]

When in the cruise in the A320 we go into 'Soft Alt Mode (Cruise)'. In this mode the Mach target is maintained by allowing a +/- 50 feet variation from the cruising flight level - this is to improve fuel efficiency. I don't know what Airbus have done to achieve this but it makes the ATHR less responsive. To achieve better responsiveness I have found selecting the speed works well. Selected modes take priority over managed modes (managed modes being based upon the information that has been inputted to the flight computers). Going man thrust is a possibility for sure and in severe turbulence is recommended - to just set the relevant N1 and try and fly the pitch.

As you may have seen with the AF447 case sometimes (especially with the Airbus) it's best to do nothing initially - less is more on this plane. That said we all know the Airbus golden rules - one of which is to take over if the aircraft isn't doing what you want. I suppose it depends on whether you are pro-acting or reacting. Either way - pause and move through the flight deck like it's filled with treacle (to again repeat something said to me by an ex BA capt who trained me early on - he came across to easy with retirement). Nothing worse than startle, impulse and thoughtlessness in these cases - especially when working in a multi crew environment. As has been said this is really just an annoying paperwork exercise on the ground.