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British Airways A350 Hard Landing at Tel Aviv

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British Airways A350 Hard Landing at Tel Aviv

Old 23rd Jan 2020, 12:29
  #21 (permalink)  
 
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Hi FlareArmed2,
Maybe I have been lucky, but we always check and adjust Vapp to at least Vls+5kts on approach, since we are often heavier than we think, and if so Vapp might not be quite right.

We also used to have "phase advance" available; where you pushed the thrust levers forward, just out of the CLB gate for literally a second, then back in the CLB gate. This was particularly useful on the A330 whose auto-thrust gains are not increased in the lower levels* - to just give a small 'blip' of power to prevent speed washing off too much. Airbus took phase advance away though, which was a shame, because it was very useful.

* Were not. Perhaps newer airframes do?
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Old 23rd Jan 2020, 17:06
  #22 (permalink)  
 
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The decision by AB to not have the thrust levers move with auto thrust definitely doesn't make it easy to control/adjust power in the flare. I often see pilots start to flare relatively early, not reducing TLA while the nose comes up. Thrust increases (speed mode), landing is long, max reverse and hot brakes as a result. I just flew with a new guy, and when I explained you could wave off from the flare without touching the thrust levers (TL in CLB detent, AT on and in speed mode, AT will keep Vapp regardless if you climb or descend) he definitely hadn't realized that was possible.

Also if you do need a little power in the final part of the approach due to a change in wind, everyone's instinctive reaction would be to advance the thrust lever, leading to a quite drastic increase in thrust. Even if you were aware enough to reduce the TLA and push the IDB, getting the right amount of power is not nearly as easy as it would be if the thrust levers moved, and you could just bump them up a bit.

Because of this I have gotten in the (bad?) habit of not using the AT on the approach often. If I do use the AT I start reducing TLA towards 1.05 EPR (mostly by muscle memory, same spot as for the T/O) before I start raising the nose. At that point I should not need full CLB power, and if I did need it, I would select TOGA and GA.
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Old 23rd Jan 2020, 19:15
  #23 (permalink)  
 
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Yep, after certain (low) altitude thrust will not increase automatically. You will see loong decreasing speed trend and most probably use full backstick to flare. And it still may by not enough. Two solutions:
- manual thrust in gusty conditions
- move thrust levers momentarily forward from CLB and immediately back to the detent. It works and definitely better then helplessly watching speed decaying.
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Old 23rd Jan 2020, 21:11
  #24 (permalink)  
 
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Originally Posted by Romasik View Post
Yep, after certain (low) altitude thrust will not increase automatically. You will see loong decreasing speed trend and most probably use full backstick to flare. And it still may by not enough. Two solutions:
- manual thrust in gusty conditions
- move thrust levers momentarily forward from CLB and immediately back to the detent. It works and definitely better then helplessly watching speed decaying.
The first part is definitely wrong for the A320 I fly. I often see people start to flare with the lever in the detent and invariably I will see an increase in thrust. This will happen all the way down to touch down.
Moving the lever forward of the CLB detent will give you full climb power if you leave it too long, IMHO it is asking for trouble.
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Old 23rd Jan 2020, 22:16
  #25 (permalink)  

Only half a speed-brake
 
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That apart from the reason the CLB+ "bump" had been removed from the manuals.

If it's done too low, the A/THR will not re-engage and the pilot is left with CLB thrust once the TLs are set back into the detent. Not compatible with landing.

Last edited by FlightDetent; 25th Jan 2020 at 02:13.
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Old 24th Jan 2020, 12:58
  #26 (permalink)  
 
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After 10000+ hours on the A320 I still wish it had a conventional auto throttle, it is the weakest part of the aircraft.






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Old 24th Jan 2020, 15:22
  #27 (permalink)  
 
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Noooooooo !

Please don't start that.
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Old 24th Jan 2020, 15:39
  #28 (permalink)  
 
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Re phase advance: As FlightDetent reminds us, if you use it below 100', auto-thrust will not re-arm, and thrust will therefore rapidly increase to the TLA position.

To use phase advance properly, you push the thrust levers forward out of the CLB gate by only about 1 cm for 1 or 2 seconds maximum, then click them straight back into the CLB gate: Click...click, like that. Auto-thrust will re-engage above 100'.

I think phase advance was poorly taught, then attempted by some who do not understand the Airbus auto-thrust logic, so they got themselves into trouble and Airbus took it away. I still use it if I need to on 'lazy' A330s, but remember if you do so below 100' RA, you will then be in manual thrust, so will then need to control thrust and speed yourself until the flare.

Probably safer, if you're not sure about phase advance, to add a couple of knots to Vapp during approach on hot, thermally days, when A330s can wallow a bit and get caught out.

Last edited by Uplinker; 24th Jan 2020 at 15:55.
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Old 24th Jan 2020, 18:27
  #29 (permalink)  

Only half a speed-brake
 
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As Uplinker reminds us, unlike the benign single-aisle models the Airbus wide bodies have a history of inadequate reactions by the A/THR. Report here.

Hopefully the present models have it well sorted out, though there is probably only so much you can do given the inertia of the airplane as well as the rotating masses inside the engines on the wide-chord installations.

Last edited by FlightDetent; 25th Jan 2020 at 02:15.
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Old 24th Jan 2020, 22:52
  #30 (permalink)  


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One of the reasons I also generally use man thrust on normal landings. A/T in association with GSmini can produce unpredictable and undesirable results at the gravy strokes.
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Old 25th Jan 2020, 15:11
  #31 (permalink)  
 
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It might say in that report @ #29 above, but I don't have time at the moment to check all 80 pages: I was told recently that narrow body Airbus FBW increase the gain of the auto-thrust below 3000', making it more responsive. For some reason the A330 doesn't or didn't have this mod, which is why it often seems lazy about correcting minus delta V's

Anybody know more?
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Old 25th Jan 2020, 15:57
  #32 (permalink)  
 
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Originally Posted by Max Angle View Post
After 10000+ hours on the A320 I still wish it had a conventional auto throttle, it is the weakest part of the aircraft.
Hours? As if hours count for anything; after 1200+ hours on autothrust equipped MRJTs and 4200+ (and counting) on the ones with autothrottle, I have no preference for either. Both have their quirks one just needs acquaint oneself with in order to have happy operational life. Still I maintain any kind of automatic thrust/power control is better than none (5000+ hrs, if you wonder).
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Old 25th Jan 2020, 16:55
  #33 (permalink)  
 
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I was told recently that narrow body Airbus FBW increase the gain of the auto-thrust below 3000', making it more responsive
From A320 FCOM below:
APPROACH AUTOTHRUST:
Below 3 200 ft RA, with at least CONF 1, the A/THR logic is modified to be more responsive to speed variation. This is referred to as approach autothrust
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Old 25th Jan 2020, 18:36
  #34 (permalink)  

Only half a speed-brake
 
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Ref: FCOM A320 (all engine types) DSC-22_30-90 "H": A/THR MODES - Speed/Mach Mode.
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Old 26th Jan 2020, 04:01
  #35 (permalink)  
swh

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Originally Posted by Airbubba View Post
Are you sure it wasn't a ferry?
It was a normal flight back, just cargo onboard to reposition for the next outbound flight. It operated the next day as BA163 to TLV.

The landing was a crew reported suspected hard landing, analysis of the electronic landing data was within normal parameters.
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Old 26th Jan 2020, 09:47
  #36 (permalink)  
 
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Oopps, I could have just looked up auto-thrust myself. Sorry guys.
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Old 26th Jan 2020, 19:14
  #37 (permalink)  
 
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Basically a non-event causing an online discussion, with the usual criticisms from people who obviously know better, by a conscientious crew who correctly reported a suspected planter.

Sometimes I really wish that information didnít leak as much as it did.
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Old 27th Jan 2020, 02:23
  #38 (permalink)  
 
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EcamSurprise

My only comment would be who initiated the nose down input!
According to flight data a loss of 5 knots of IAS occurred as result of a gust (increasing tailwind) which prompted a nose down input and high rate of descent.
.
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Old 27th Jan 2020, 03:49
  #39 (permalink)  
 
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Originally Posted by iceman50 View Post
EcamSurprise

My only comment would be who initiated the nose down input! .
I would assume that the A350 (which I haven't flown) is pretty much the same as the A330 and A340 (which I have flown) in that the Stabilizer (auto trim) freezes at 100 feet RA for the FCS Flare Mode. That leaves only the elevators controlled by the sidestick to flare the aircraft.

At the instant that the Stabilizer freezes, it could be out-of-trim, depending on the conditions experienced passing 100 feet RA. That is, if a large up or down pilot sidestick command was taking place, thrust was above or below the mean, airspeed was above or below VAPP, and rate of descent higher or lower than the mean.

With the Stabilizer in an out-of-the trim position, unusual push or pull force is required on the sidestick to maintain the required vertical profile and again, unusual stick force to accomplish the desired flare manoeuvre.

With due regard to the control system Flare Mode action of the Stabilizer, in gusty conditions, the aircraft response can surprise pilots with an unexpected change in rate of descent, especially when the Stabilizer is frozen Aircraft Nose Down, and then the arse falls out of it.

If the A350 does not have the same FCS Flare mode as the A330/A340 regards the Stabilizer...then please ignore all above.


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Old 27th Jan 2020, 06:15
  #40 (permalink)  
 
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FlexibleResponse

I should have included in my quote
at 70'RA
I have flown A330/A340 and A350 and understand what you are saying. My question was why input nosedown at 70' for a loss of 5 kts?
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