Inhibition of speed brakes following config full - A320

[Travelbird .320]

Hello everyone,

Been trying to find out a probable reason for inhibition of speed brakes following landing flap full configuration on the A320s ?

Thank you.

[Goldenrivett]

In case dozy Nigel still attempts to Land with speed brakes deployed.

[Amadis of Gaul]

That's nothing, on the E170/190 the speedbrakes are inhibited anywhere past Flaps 1.

[vilas]

What is there to find out? Just think about the drag with gear down plus flaps full and speed brakes. with speed brakes even without flaps at Green Dot speed itself there is so much increase in VLS. With flaps full there is no margin for it and will trigger alpha floor. If you need speed brakes with flaps full you should be executing missed approach.

[PJ2]

My guess is that roll gain is slightly higher with Config 4 and would be higher still with the additional roll available with speedbrakes extended.

[FlightDetent]

IIRC on A319 and 321 it's flaps 3 that do not mix with speedbrakes. Just an observation...

[vilas]

PJ2
Gain is higher in Conf3 and before trying to find out why A320 it is not allowed it may be interesting to find out if there any aircraft that recommends the use of speed brakes in full configuration.

[RunSick]

A330 allows speedbrake with CONF FULL.

[vilas]

RunSick
Do you really fly the A330? I so a ground subject refresher is due. Pleas read below from A330 FCOM:


Ident.: PRO-NOR-SOP-18-B-B-00014481.0001001 / 29 MAY 13




AT 2500 FT AGL MINIMUM


FLAPS2...................................................... ............................................................ .........ORDER


FLAPS 2 lever....................................................... ............................................................ ....SELECT




‐ Check deceleration toward "F" speed.


‐ For ILS / GLS  and approaches using FLS  , if the aircraft intercepts the flight path below


2 500 ft AGL, select FLAPS 2 at one dot below the flight path.


‐ If the aircraft speed is significantly higher than "F" speed on the flight path, or the aircraft does not decelerate on the flight path, extend the landing gear in order to slow down the aircraft. The use of speed brakes is not recommended.


‐ When the speed brakes are deployed, extending the FLAPS beyond FLAPS 1 may induce a slight roll movement, and in calm conditions a small lateral control asymmetry may remain until disturbed by a control input or by an atmospheric disturbance.


When speed brakes are not recommended at flaps2 the question of flaps full does not arise.

[Check Airman]

Not recommended isn't the same as not permitted. I don't fly the 330, but I think that if Airbus didn't want the speedbrakes out with full flaps, they'd have designed the system to work like it does in the 320. Seems as if Airbus has left it up to the pilot's judgement and the scenario at hand.

Certainly the manufacturer's recommendation will be taken into account, but I wouldn't fault him for using speedbrkes with full flaps if he deems it necessary, given the limited information in this thread.

[vilas]

Not recommended isn't the same as not permitted. I don't fly the 330, but I think that if Airbus didn't want the speedbrakes out with full flaps, they'd have designed the system to work like it does in the 320. Seems as if Airbus has left it up to the pilot's judgement and the scenario at hand.

Certainly the manufacturer's recommendation will be taken into account, but I wouldn't fault him for using speedbrkes with full flaps if he deems it necessary, given the limited information in this thread.Check Airman speed brake increases Vls. As I mentioned before it will trigger alpha floor as there is no margin.The recommendation has some meaning. Even at GD speed it difficult to use. Not recommended does not mean permitted it only means it is possible with associated consequences.

[RunSick]

Hi Vilas, yes, I do fly the 330 and I have used the speedbrake with CONFIG FULL quite a few times..That plane loves to fly and sometimes with speed control of 160kts till 4NM... well, they come in really handy. No big issue on that my friend. On the A320 on the other hand it is not allowed. Cheers!

[RunSick]

You can do the same on the 340, by the way. I have never needed it on that plane, but it is an option. On the 320, if you read the procedures, after selecting CONF FULL it says that you should retract the speed brakes before selecting CONF FULL because they will automatically retract, causing a pitch down. That note is not applicable for the 330/340.

Now, do you fly any of those planes?

Cheers!

[vilas]

RunSick
A320 yes I have. My point was I have not seen it recommended on any aircraft B747,707, A300, A310, and A320 or A330 for that matter. It is not inhibited on A330 but so was on all other aircraft. All had the same recommendation not to. Why is that? It means A330 is similar in this respect. And quiet a few times means routinely doing something not recommended. You are not expected to accept ATC speed restrictions if you have to do something not recommended. Anyway it's your problem. Good luck.

[RunSick]

Hi Vilas,
mate you need to relax a bit. First this thing you told me about "needing a refresher course" (when you have not even operated the aircraft in question) and then stating that it is my "problem". Well, yes, I guess it is, but... it really is not a problem. Maybe you should consider that you do not have the final say all on things?

Also, what is all this anxiety about VLS and ALPHA FLOOR? ALPHA FLOOR will trigger at some point between Alpha Prot and Alpha Max. It doesn´t have a set point and it is not related anyway to VLS.

"ALPHA FLOOR protection is triggered when the FMGECs recieve a signal elaborated by the PRIMS. This signal is sent when the aircraft´s ange of attack is above a pre-determined threshold function of the aircraft´s configuration"

"ALPHAFLOOR is activated through the autothrust system when : alpha is greater than a threshold depending on the aircraft configuration, the ground speed variation, and the difference between ground speed and air speed..."

"If a pilot attempts a stall, he feels the aircraft trying to pitch down as speed approaches the amber and black strip. The pilot can resist this tendency until speed reaches the red band (alpha maximum), and then further nose down is not available. Between this two points alpha floor automatically sets go around thrust."

Cheers!

[Stone_cold]

Vilas always has to have the last say Gents . Don't get wound up . He usually quotes some abstract document from an Airbus conference . The A380 also has speedbrake capability in full .

Vilas : The OP asked why and it is a fair question as it is not INHIBITED on other types . Instead of your pompous knowitall answers , answer the actual question if you can . Recommended and inhibited are 2 different issues ! As for the 747-4 , there is no note , recommended or not (that I can find , 767 and 777 included ) . Where does it say specifically "not recommended" on Boeing types ? Very dismissive answers to anyone who doesn't agree .BTW , when referencing material , get a current manual ! And as Runsick said , AI also has a note before selecting Flap Full to retract speedbrake , so obviously the manufacturer recognizes that speedbrake may be needed and used whenever deemed necessary .

[vilas]

RunSick
If I ruffled feathers my apology. I quoted FCOM not my opinion. I am trying to make a sense between three entities, the manufacturer, the employer and the pilot. So some question come to mind. Let's continue the discussion. I am aware about what you said about alpha floor. What I said came from FCOM:

If the flight crew uses the speed brakes to increase the rate of deceleration or to increase the


rate of descent, the VLS will increase as well:


• The flight crew should ensure that appropriate speed margin exists before the extension of


the speed brakes


• If the speed brakes are extended, the flight crew should ensure that appropriate speed


margin exists before the beginning of a turn.


This will avoid the activation of the Alpha-Floor protection.


So how to manage that at 4miles and yet be stabilised at 3miles(1000ft)?
Forbidden is rarely mentioned in manuals, generally not recommended is used. All things being normal how does one decide when to disregard manufacturer's recommendations?
What is the preferred course of action? during approach? Not accept ATC constraints requiring non recommended pilot action or accept them at any cost? The first course is recommended in FOBN.


Stone_cold

You express your opinions and don't like it when manufacturer's documents prove them wrong. You are the one and not me who has the last say even when proved wrong by Airbus document by calling them abstract. I am surprised that you are asking me to provide another reference when it will be termed obscure by you as in the past. The only problem with me is that I believe in manufacturer's expertise in stating how their product is safely used. I am interested in exchange of information and you are welcome to provide it.

[Goldenrivett]

Horses for Courses.

If you really want to fly with Flaps Full and Full Speed Brake on A320 series, then I suggest you fly A318.
http://www.dream-air.ru/new/pilotam/13_steep_approach.pdf
"Gear Down
 CONF FULL
 SPD BRKS lever FULL → Only SPLR 3+4 are extended to 30°"

[vilas]

This is so as to prevent a diving approach at idle thrust by adding a controlled calculated drag from speed brakes.

[vilas]

Another abstract document. This time from Boeing for those who might be interested.


FCT 737 NG (TM)
The use of speedbrakes with flaps extended should be avoided, if possible. With
flaps 15 or greater, the speedbrakes should be retracted. If circumstances dictate
the use of speedbrakes with flaps extended, high sink rates during the approach
should be avoided. Speedbrakes should be retracted before reaching 1,000 feet
AGL.

[RunSick]

Hi Vilas,

"So how to manage that at 4miles and yet be stabilised at 3miles(1000ft)?"

That is a very valid question.

Where I operate, If given ATC speed control you have down to 500ft to get the speed parameter inside the stabilized approach criteria. ONLY speed, and ONLY when ATC has given speed control.

About the speedbrake use and VLS etc. I will tell you how I do it, and this is not more than that, my personal technique/idea/whatever:

First I try to avoid doing it unless really required. Saying unable is of course a more than valid option.

Then, when using the speed brake you don´t have to go either 1/2 or full, a gentle gradual extension monitoring VLS and the speed trend arrow is better. I have found that in the end no more than around 1/4 should be required and also that once the speed starts going down you can put them back in.

In the 330 I think it is just about putting some dirt on the wing and kind of "breaking the inertia". There are a few seconds between pressing for managed speed and the speed really starting to go down that are the problem and can be crucial in order to reach Vapp before 500ft.

I´ve never needed to use them on the 340 with CONF FULL. I think this comes to be more an issue of the 330.

Cheers!

[vilas]

May be it is more critical in A320 CG etc. Even A330 flare mode pitch down is not that pronounced as in A320.