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PULSARTEK
20th Nov 2014, 22:27
NOT A PILOT:

Was on board A320 during domestic flight, and something caught my attention.

During a 180 turn ( Looks like a steep turn) into final ILS Approach for landing, pilots had the spoilers (air brakes) deployed to about 30% of full scale up diflection.

1. Is this correct procedure for this type of aircraft.
2. Is this increase stall chances.

Thanks,

Nitzan K
Test Engineer

Nowayjose
21st Nov 2014, 09:38
At that stage of flight, the gear would be up, and you would be pribably speed limited to use much flap, if you are trying to decend and slow down, this is difficult in a modern jet as they are so 'slippery'

Spoilers would slow it down to a speed safe to operate gear and flap. They would still be waaaay above the stall speed.

ASRAAM
21st Nov 2014, 12:21
The bus, like many modern airliners is fairly slick,ie reluctant to go down and slow down at the same time. In order to maximise runway utilisation controllers will feed aircraft around base turns prior to the ILS at speeds designed to achieve the correct spacing.They may also reduce ground track to further help. So if you are 220 knots on base and fed in fairly tight or even if you intercept the glide at 180 kts and the headwind is light some speed brake or an early gear selection will be required.

The deployment of speed brakes will as you suggest cause an increase in the red line ( minimum speed you are allowed to fly). This can be countered by flaps

PULSARTEK
21st Nov 2014, 14:05
Thanks for the quick response:
Understand the necessity of slow speeds and terrific separation. But my concern was, are pilots allowed to use spoilers during slow speeds and steep turns when the load on the wing increased. As I was thought that stall can occur in any speeds, and in any angle of attack regardless of configuration.


It was possible to wait to finish the turn before use of spoilers.


Regards,

glendalegoon
22nd Nov 2014, 04:25
dear pulsartek


spoilers can actually be used in many ways.

spoilers can be used to augment roll control, in which case spoilers will come up on one wing and not on the other

spoilers can be used as speedbrakes, in which case they will come up on both wings at the same time.


spoilers can be used to destroy lift upon landing to ensure all the weight of the plane is on the wheels which helps stop the plane using wheel brakes.

and the funny thing is the spoilers can, but not always be, the same piece of the wing...just used in a different way.

Some speedbrakes on planes are different, the BAE146 has a funny little speedbrake on the tail of the plane. Speedbrakes on some fighter planes are really funny looking, and usually on the fuselage.


So, yes it was probably normal that you saw these spoilers deployed to aid in descent. And yes, if you kept the spoilers out you would probably stall at a higher than normal airspeed or you would reach the stalling speed much faster by having the spoilers out.

And there are some planes you are not to extend spoilers when the flaps are extended

And there are other planes that you CAN extend spoilers when the flaps are extended.

AND if you want to ask the pilots next time, be sure to do so...you can easily sound like you know what you are talking about by saying: DID ATC KEEP YOU TOO HIGH? I saw the spoilers out.


So spoilers can be used, in different ways at different deflections for different reasons.

PULSARTEK
24th Nov 2014, 17:44
Tanks for the prompt response, from all responses I received, it looks that no wrong was done. but as everywhere else its better to be on the safe side.

Thank you all.