Point of speedbrakes ARMED during T.O A320
 

It's still good to have Armed speedbrakes at T.O in an A320, But when rejecting take off and as soon as reverse is selected on atleast one engine the speedbrakes extend no matter what. So what is the point of putting it in Armed position..

If they're armed they will extend when the thrust is selected to idle. If they are not armed they will only extend if reverse is selected.

Autobrake will not activate unless the spoilers extend, and they will only extend after 72 knots regardless of spoiler handle position.

I guess arming them is simply to mitigate against a case during a rejected TO where idle is selected by reverse is not.

Let's put it another way: why would you NOT arm them?

In case of people set thrust levers to idle and forget to set one thrust reverser in IDLE for exemple

My FCOM says DSC 27-10-20 SPEED BRAKES AND GROUND SPOILERS

GROUND SPOILER CONTROL

Spoilers 1 to 5 act as ground spoilers.
When a ground spoiler surface on one wing fails, the symmetric ground spoiler surface on the other wing is inhibited.

ARMING
The pilot arms the ground spoilers by pulling the speedbrake control lever up into the armed position.

FULL EXTENSION – REJECTED TAKEOFF PHASE
▪ If the ground spoilers are armed and the speed exceeds 72 kt, the ground spoilers will automatically extend as soon as both thrust levers are reset to idle.
▪ If the ground spoilers are not armed and the speed exceeds 72 kt, the ground spoilers will automatically extend as soon as reverse is selected on one engine (the other thrust lever remains at idle).


DSC 32-30-10 AUTOBRAKE -GENERAL

SYSTEM ACTIVATION

Automatic braking is activated:

‐ at the command for ground spoilers extension (Refer to DSC-27-10-20 Speed Brakes and Ground Spoilers - Speed Brake Control), for LO and MED mode.

‐ at the command for ground spoilers extension and the aircraft speed is above 40 kt, for MAX mode.

Therefore, if the aircraft makes an acceleration stop and begins to decelerate when its speed is under 72 kt, the automatic braking will not activate because the ground spoilers will not extend.
For autobrake to activate, at least two SEC's must be operative.

Http://www.a320quiz.com

The spoilers are so very important for reject stopping performance. The distance traveled while you are selecting reverse thrust can be enough to make the difference between an over run or not. The spoilers also put the weight on the wheels and make braking that much more effective.
Arm your speed brakes; its costs nothing.

It's not required to ARM speedbrakes in A320 as once idle is put it will extend speedbrakes, it's recommended to put armed position though.

But thank you for your answers! and opinions!

BEL1000
What do you mean by that?

It is permissible to dispatch the A320 (subject to your own MEL-Not all allow it!) with both thrust reversers inop.

In the reject case, the technique stipulated by the MEL is to retard the thrust levers to idle and not to select reverse (I guess to avoid the increased idle reverse thrust brings). If you haven't armed the speedbrake prior to T/O where does that leave you?

If the lever is there for you to arm them, just do it. If it was meant to be done in a different way, the lever wouldn't be there.

It doesn't extend unless you arm it. Also wrong conlcusion Not required but recommended.
You are thanking everyone without having understood anything.

FCOM is quite clear....arm the ground spoilers after start.

Apart from anything else the T/O config. test will fail if the spoilers are not armed.

Do you have a reference for that?
My FCOM says CONFIG SPD BRK NOT RETRACTED

However the TO MEMO would have the blue line "SPD BRK".

Goldenrivett
How do you explain the following part about 4okts. Then where does 72 kt get in?


DSC 32-30-10 AUTOBRAKE -GENERAL

SYSTEM ACTIVATION

Automatic braking is activated:

‐ at the command for ground spoilers extension (Refer to DSC-27-10-20 Speed Brakes and Ground Spoilers - Speed Brake Control), for LO and MED mode.

‐ at the command for ground spoilers extension and the aircraft speed is above 40 kt, for MAX mode.

Therefore, if the aircraft makes an acceleration stop and begins to decelerate when its speed is under 72 kt, the automatic braking will not activate because the ground spoilers will not extend.
For autobrake to activate, at least two SEC's must be operative.

Looks like you are right, will try it next time I am on the a/c.

Hi Vilas,

72kts logic for ground spoiler activation during RTO is common. (same as B747-400 from memory)

The 40kt logic is to prevent a dozy crew hurting standing cabin crew if they select MAX autobrake during taxi out and the ground spoilers haven't been stowed from the previous landing. I know it's hard to believe but some manage to miss it during the after landing checks and pre-departure checks. I think it will only activate the MED setting below 40kt. (I've never tried it myself).

That's why the flight control checks are performed before the MAX autobrakes are armed during taxi out. Hopefully the dozy crew will then notice the ground spoilers are still deployed from the previous landing.