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-   -   Flying below VAPP - What to do ? (https://www.pprune.org/tech-log/565790-flying-below-vapp-what-do.html)

Zenj 7th Aug 2015 08:42

Flying below VAPP - What to do ?
 
on approach with auto thrust on , you find speed going below VAPP or even getting to VLS , what do you do to recover back to your VAPP ?

Thanks

DJ77 7th Aug 2015 08:51

I would recommend you should start praying seriously (for once).

Ollie Onion 7th Aug 2015 09:05

^^^^ What he said!

safelife 7th Aug 2015 09:12

Another option, but thrust levers into FLX/MCT momentarily.

PURPLE PITOT 7th Aug 2015 09:13

I have to assume you are talking about one of those death busses, otherwise you could simply mover the thrust levers to an appropriate position, you know, like a pilot:ugh:

safelife 7th Aug 2015 09:19

I'm aware. But it was, for many years. As I wrote, another option.

ACMS 7th Aug 2015 10:31

Momentarily advancing the thrust levers forward of the detent is perfectly fine.

Just make sure you are in a modified Aircraft otherwise below 100' AGL it will get interesting when you put them back :eek::eek::eek: All of ours are modded and if required I've been known to employ this method when I see IAS heading south and the A/T slow. Seems to work ok.

C_Star 7th Aug 2015 10:35

@ACMS

What happens in non-modiefied a/c?

ACMS 7th Aug 2015 10:36

A330 FCTM quote with regards to loss of speed:---

In gusty wind conditions, the A/THR response time may be insufficient to cope with an instantaneous loss of airspeed. A more rapid thrust response can be achieved by moving the thrust levers above the CL detent (but below MCT). The thrust will quickly increase towards the corresponding TLA. The A/THR remains armed and becomes active immediately the thrust levers are returned to the CL detent. Therefore, the thrust levers should be returned to CL detent as soon as there is a positive speed trend. However, there are two important points to note:



‐ Selecting the thrust levers to the TOGA detent, even momentarily, will engage the Go-Around mode,
and. ‐ In some aircraft selecting the thrust levers above the CL detent below 100 ft RA will disconnect the A/THR. In this case, returning the thrust levers to the CL detent will set climb thrust. Refer to FCOM DSC-22_30-90.

C_Star 7th Aug 2015 10:42


Selecting the thrust levers to the TOGA detent, even momentarily, will engage the Go-Around mode,
and. ‐ In some aircraft selecting the thrust levers above the CL detent below 100 ft RA will disconnect the A/THR. In this case, returning the thrust levers to the CL detent will set climb thrust. Refer to FCOM DSC-22_30-90.

Oops, that might make things interesting...:E Not the loss of autothrust itself, but the unexpectedness of it... Is it an A330 specific thing, or do A320 have this as well?

ACMS 7th Aug 2015 10:55

Yes it's caught out a few boys and girls in the past but not now as we all know about it. ( no I'm not one :ok:)

Don't know about the 320 but it's probably similar?

Amadis of Gaul 7th Aug 2015 14:23


Originally Posted by safelife (Post 9073680)
Another option, but thrust levers into FLX/MCT momentarily.

I was taught that option during OE. Only had to do it once in 18 months, though.

safelife 7th Aug 2015 14:39

Does any operator actually do approaches with autothrust on the A330?
I know it's common on the A320 but on the Airbus 330 the speed tracking is dismal to say the least.

ACMS 7th Aug 2015 14:51

Yes it's standard Airbus ops at our mob and we have the largest fleet of A330's in the world ( or at least we did )

I use it unless it's really gusty, then I'd rather do it myself, unlike the mighty 777.

sierra_mike 7th Aug 2015 14:52

from FCTM/NO-Normal Operations/NO 110-Approach General/FINAL APPROACH


If the A/THR performance is unsatisfactory, the pilot should disconnect it and control the thrust manually.

Intruder 7th Aug 2015 16:30


on approach with auto thrust on , you find speed going below VAPP or even getting to VLS , what do you do to recover back to your VAPP ?
If you have to ask, go back to flight school or find another career!

RAT 5 7th Aug 2015 18:24

Reading this scares me a little. I am a Boeing pilot and know nothing first hand of the AB families. I also fly small piston a/c. In all my types of a/c over a long career thrust management has always been very simple. Forward = more and backward = less. As Pf you decide what datum to set and adjust around that. A/T might be used on later types, but needed watching and if it was slow to respond then my hand was always rolling through and told the silly billy what to do. never a word of thanks. Watching cadets in TR plug in the automatics and them not monitor them is most amusing, especially if they haven't noticed A/T has gone not ARM. The speed goes off the end or decays in to stick shaker: and I let it. They seem so bewildered that "the computer was engaged and it didn't do its job." A salient lesson learnt and never forgotten.
Back to my point; thrust/speed management was easy and intuitive. Now I read about the AB types that do this or that if you select this detent or that, and if you do this above 100' the a/c will assume this and if you do it below 100' it will assume something else and thus cause a whole chain of events to try and catch you out. Am I being staid in my ways or are they making an easy job difficult? If I first have to think about what else will happen if I push the thrust levers forward or backwards and by how much then it might cause unwanted hesitation, especially if operating different modified thrust systems e.g. A320 & A330 as has been mentioned here. Ouch.

JulietSierra6 7th Aug 2015 20:13

Clearly this is an Airbus specific topic but I have to agree with a few of the other guys. This discussion shocks me to say the least. All my limited experience is of Boeing but come on, can you hear yourselves?

I don't know whether to laugh of cry.

Case One 7th Aug 2015 20:52


Originally posted by ACMS:
Don't know about the 320 but it's probably similar?
It certainly was when I flew them, but that was over a decade ago. Landing in moderate/ severe turbulence could be interesting. With your entire body bouncing around, your hand on the thrust levers could easily knock them slightly out of the gate. The chime and ECAM caution weren't particularly attention getting in that situation, and an already entertaining approach could see a surprising flare.

Nice to see those with no AB experience chiming in as usual. Boeing's moving thrust levers are great, and speed tracking does seem better than on the 330/340. However, on AB's non-de-rated types; just pushing fully foward for TOGA thrust and guidance beats Boeing's TOGA button logic/ finger faffing hands down. Not to mention the dubious wisdom of HOLD mode, or having to frequently over-ride the autothrottles on an RNAV STAR in VNAV. A bit like flying with an obstinately poor student. Neither system is perfect and both present opportunities for embarrassment, especially when converting between them.

hikoushi 7th Aug 2015 23:45


Originally Posted by Zenj (Post 9073659)
on approach with auto thrust on , you find speed going below VAPP or even getting to VLS , what do you do to recover back to your VAPP ?

Thanks

Step by step:

1. Disconnect all automation.

2. Add power.

3. Put the nose down a little.

4. When speed trend recovers and you start to feel a little "whooop" lift in the seat of your pants, reverse the motion and recover flight path.

5. Land.

If that all seems improbable at the time choose option B.

1. TOGA / GTFOOD (Get The F Out Of Dodge).


Also, the Airbus G/S Mini mode WILL allow speed to decay below Vapp momentarily in very gusty situations. It won't allow it to decay below Vls if all works as advertised. Regularly land in very gusty wind and it does in fact work quite well (A330). Like others have said I do like the feel of manual thrust in those conditions. Hold a stable power setting and let the speed vary a little. Which, come to think of it, is basically what the G/S Mini function is trying to accomplish anyway by giving you a variable speed target.

If the automation doesn't do the job, turn it off. If you work for a company that absolutely forbids this, or you are simply not comfortable doing so, then your choice is simple, go land somewhere else. Bottom line.


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