Airbus Spoilers Deployed...

redtail

redtail

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Redtail
...during the takeoff roll!

I don't fly the airlines that often but when I do, I usually get a window seat because I enjoy the view. Two days ago while departing SFO runway 1L, on an A320 enroute to JFK, I noticed something that I have never seen before and it had me a little concerned. The spoilers were up during the takeoff roll and for a brief moment after liftoff. My son was sitting next to me as I was recording the takeoff.

My first thought (which honestly freaked me out a little) was, that there was a takeoff configuration mistake. However, after we successfully took off and I observed them retract, that thought dissipated and I convinced myself that everything was ok.

I know the Airbus is FBW, so my question is: Is that normal? Can someone explain what was going on?

Thanks.
By the way, I have no real world jet experience and my flightsim experience has been primarily Boeing aircraft (PMDG 737, 747 and Level-D Simulations 767).;)
 
Were all the spoilers on the wing up or just the outboard ones? Was the aileron on that side also up?
 
SkyDog58 said:
Were all the spoilers on the wing up or just the outboard ones? Was the aileron on that side also up?
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Appears to be all of the spoilers. After reading your post, I watched it again and just noticed that the aileron does go up a little after we lined up on the runway (hadn't noticed that initially). But the spoilers didn't retract until we were airborne. The flaps looked like they were set correctly for takeoff.

One small detail I forgot to mention. As we lined up the spoilers were down, they didn't go up until a few seconds before the takeoff roll began.
 
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Ryanb said:
Hmm.. I would guess this too. Aileron movement also uses spoilers. Was it a bumpy climb out?
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A little bumpy, nothing extreme.

So are you saying this was aileron & spoiler deflection (roll control) as per a normal crosswind takeoff? If so, then does that indicate that the spoilers on the other wing were down?

I hadn't considered that. I assumed they both were up (although I couldn't see the right wing).
 
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here is how the 320 system works. there are 5 spoiler panels on each wing, 1 through 5. #1 is the inboard most board. 2,3,4,5 are used for roll control and deflect when a roll input is put on the side stick. ground spoilers use all 5. speed brakes use 2,3,4. part of the captains after start flow is to arm the ground spoilers, once armed the logic tree to extend the spoilers fills a whole page. bottom line is that all 5 spoilers can open only if a bunch of things happen. any system failure and they fail safe to close. if a side stick input was made spoilers 2-5 will deflect, that is why SOP on the bus is to not use aileron input in a crosswind takeoff. i have not seen your video, but i am guessing that the pilot was holding some side stick input, and you were seeing panels 2-5. not panel 1.

bob
 
unsafervguy said:
here is how the 320 system works. there are 5 spoiler panels on each wing, 1 through 5. #1 is the inboard most board. 2,3,4,5 are used for roll control and deflect when a roll input is put on the side stick. ground spoilers use all 5. speed brakes use 2,3,4. part of the captains after start flow is to arm the ground spoilers, once armed the logic tree to extend the spoilers fills a whole page. bottom line is that all 5 spoilers can open only if a bunch of things happen. any system failure and they fail safe to close. if a side stick input was made spoilers 2-5 will deflect, that is why SOP on the bus is to not use aileron input in a crosswind takeoff. i have not seen your video, but i am guessing that the pilot was holding some side stick input, and you were seeing panels 2-5. not panel 1.

bob
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very interesting! Thanks. So, if I understand you correctly, during a crosswind takeoff the SOP is to maintain neutral side stick and the FBW computers will determine the correct amount of aileron-spoiler deflection based on the wind?
 
unsafervguy said:
here is how the 320 system works. there are 5 spoiler panels on each wing, 1 through 5. #1 is the inboard most board. 2,3,4,5 are used for roll control and deflect when a roll input is put on the side stick. ground spoilers use all 5. speed brakes use 2,3,4. part of the captains after start flow is to arm the ground spoilers, once armed the logic tree to extend the spoilers fills a whole page. bottom line is that all 5 spoilers can open only if a bunch of things happen. any system failure and they fail safe to close. if a side stick input was made spoilers 2-5 will deflect, that is why SOP on the bus is to not use aileron input in a crosswind takeoff. i have not seen your video, but i am guessing that the pilot was holding some side stick input, and you were seeing panels 2-5. not panel 1.

bob
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This.... With the exception of a couple company specific SOP's, but the system logic is correct.
 
You use neutral side stick to keep the spoilers closed to reduce drag and use rudder to maintain center line. Once you rotate you then use side stick to keep wings level. You also do the same on landing, crab right down to the ground and rudder to straighten it out at the last moment,but you do not put in wing down input. It takes getting use to. My guess is the pilot and on that flight was putting roll input in without even noticing it.

Bob
 
redtail said:
very interesting! Thanks. So, if I understand you correctly, during a crosswind takeoff the SOP is to maintain neutral side stick and the FBW computers will determine the correct amount of aileron-spoiler deflection based on the wind?
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The flight control computers will not input aileron deflection for wind.
Our SOP is to use minimal side stick input during takeoff. Basically just enough to keep control of the airplane.

Not sure about Bobs SOPs
 
unsafervguy said:
You use neutral side stick to keep the spoilers closed to reduce drag and use rudder to maintain center line. Once you rotate you then use side stick to keep wings level. You also do the same on landing, crab right down to the ground and rudder to straighten it out at the last moment,but you do not put in wing down input. It takes getting use to. My guess is the pilot and on that flight was putting roll input in without even noticing it.

Bob
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Wow, I can't even imagine crabbing all the way down to the runway! But thanks for explaining it to me. Anyhow, if the pilot was inadvertently putting in roll input, then what I was seeing was indeed out of the norm. I'm guessing it's nothing bad as long as it's "into the wind".
 
Kritchlow said:
The flight control computers will not input aileron deflection for wind.
Our SOP is to use minimal side stick input during takeoff. Basically just enough to keep control of the airplane.

Not sure about Bobs SOPs
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I understand, thanks. This was just something I've never noticed before and it looked strange. Wish I could upload the video. It's a JVC .mod file
 
So how do you keep the upwind wing from lifting during x-wind ground roll? That's some major side load on the downwind strut if aircraft roll attitude is left to its own devices....
 
hindsight2020 said:
So how do you keep the upwind wing from lifting during x-wind ground roll? That's some major side load on the downwind strut if aircraft roll attitude is left to its own devices....
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Our sop is to use "just enough" for a safe takeoff.
Flying a heavier airplane is a bit different than a small GA airplane. Things just don't happen as abruptly.
 
I would think a smart aircraft like that wouldn't allow aileron input to spoilers with weight on wheels (ground sense), speed brakes is another story. Could you see spoilers on both wings?
 
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redtail said:
Wow, I can't even imagine crabbing all the way down to the runway! But thanks for explaining it to me. Anyhow, if the pilot was inadvertently putting in roll input, then what I was seeing was indeed out of the norm. I'm guessing it's nothing bad as long as it's "into the wind".
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No idea about the 'bus, but some jets (including a couple I fly) have a form of an rudder to aileron interconnect programmed into their FCS logic in the landing configuration, i.e. it automatically inputs some rudder when aileron inputs are made. In some cases (again, not sure about the 'bus), you don't want to counter a crosswind with aileron for this reason lest you induce a PIO, and will instead rely on NWS and/or rudder to do it. I also fly a different jet, that requires really hard rudder pressure in the aerobrake during a crosswind landing to maintain centerline……like uncomfortable amounts, while the thing essentially skids on the mains all the way down the runway in a full crab.
 
I used to fly the citation X. The wings were so swept (37°) that you had a 5/7 window before scraping a wing. If you flared 5°, you could bank 7°, or the other way around.
If forced you to learn the "kick it & stick it" method of landing. It works just fine with a heavier airplane.
 
You will see the same thing here.

<iframe width="420" height="315" src="
" frameborder="0" allowfullscreen></iframe>
 
1L is almost always going to be facing a crosswind. And there's a 1R that would also be in heavy use at SFO. (28 L and R would be the usual headwind runways, which is why they are generally used for arrivals and the 1's are only used for departures.)

If I had to guess, I'd say that the prevailing wind from the NW made the pilot either consciously or subconsciously wary of drifting towards 1R, resulting in the control input. But it's just a guess.
 
midwestpa24 said:
You will see the same thing here.

<iframe width="420" height="315" src="
" frameborder="0" allowfullscreen></iframe>
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Yep. Ours weren't moving as much, probably due to the milder conditions. We were in clear weather.
Interesting, but it's still unclear to me if this is normal, voluntary inputs by the pilot for roll control or due to poor takeoff technique outside of the SOPs. Perhaps due to being used to flying other aircraft?
 
Your lucky you made it out alive...he was probably out of control
 
CC268 said:
Your lucky you made it out alive...he was probably out of control
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haha, yeah it was the only time I've ever worried about the success of the takeoff. At first I thought it went up due to the pre-takeoff flight controls check. But when it stayed up as we accelerated, I was actually scared, wondering how the heck we were going to generate enough lift for takeoff! Again, I was assuming they were deployed equally on both wings (I was on the left side). It never occurred to me that this was a roll control input.
 
redtail said:
Yep. Ours weren't moving as much, probably due to the milder conditions. We were in clear weather.
Interesting, but it's still unclear to me if this is normal, voluntary inputs by the pilot for roll control or due to poor takeoff technique outside of the SOPs. Perhaps due to being used to flying other aircraft?
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Remember it's FBW, so the pilot may be making small corrections for x-wind and the control surfaces may be moving all over the place to get that done.
 
GlennAB1 said:
I would think a smart aircraft like that wouldn't allow aileron input to spoilers with weight on wheels (ground sense), speed brakes is another story. Could you see spoilers on both wings?
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on the bus the spoilers and ailerons are interconnected all the time.if speed brakes are deployed you only get 3 boards and ground spoilers you get 1 and five only. the only way to get all five out is on landing, or rejected TO with ground spoilers deployed and a roll input on the stick.


bob
 
redtail said:
haha, yeah it was the only time I've ever worried about the success of the takeoff. At first I thought it went up due to the pre-takeoff flight controls check. But when it stayed up as we accelerated, I was actually scared, wondering how the heck we were going to generate enough lift for takeoff! Again, I was assuming they were deployed equally on both wings (I was on the left side). It never occurred to me that this was a roll control input.
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Well statistically about 50% of takeoffs and landings are just barely pulled off...I don't fly commercially way too dangerous...just kidding...but commercial flights really scare me
 
GlennAB1 said:
Didn't need to say, "the bus" then, did we.
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496.jpg
 
GlennAB1 said:
Didn't need to say, "the bus" then, did we.
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we sure did…….myself mostly. As long as it is a long haul AA A321 with wifi, those fancy power outlets on the seat backs, free movies, and I'm in the exit row(s), I'll call it anything you like :)
 
Guy had a crosswind and was putting ailerons(which include spoilers on larger jets) into the wind. Normal crosswind procedure, at least on the DC-10. I don't know about the Airbus.
 
Reviving the thread for a comment for @redtail ...

The reason they're used with the ailerons in many of these aircraft is a spoiler roll control will generate a LOT less adverse yaw than ailerons big enough to roll a big aircraft like that. And less overall drag if you don't need a lifting force on the other wing. Plus less drag from the rudder to counteract the adverse yaw.

Works on smaller lighter stuff too, of course. MU-2 for the ultimate incarnation of that. Less drag, more go, if you can just pop one up on the side you want to kill some lift on.

Various aircraft types play different games with it. Some can split the ailerons and only stick one up instead of moving both, at certain speeds...

Just one example of aerodynamic "fun" possible when the surfaces are not interlinked with something physical and computers are driving.
 
Many airliners lock out the outboard ailerons for high speed flight and they become active with flap extension.

Spoilers increase roll effectiveness and allow for use of smaller Ailerons, reducing stress on the wing.

The L-1011 had a unique system called Direct Lift Control (DLC). It activated spoilers with aircraft nose down (AND) Elevator input.

There are all kinds of variables out there.
 
GlennAB1 said:
Many airliners lock out the outboard ailerons for high speed flight and they become active with flap extension.

Spoilers increase roll effectiveness and allow for use of smaller Ailerons, reducing stress on the wing.

The L-1011 had a unique system called Direct Lift Control (DLC). It activated spoilers with aircraft nose down (AND) Elevator input.

There are all kinds of variables out there.
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Cool. Didn't know those. So many interesting variants.

When I do bother to ride commercial, I love to watch the dance. It's too bad they don't put a big cushy first class seat right behind the wing! Heh. I'd pay real money for that. Haha.

I usually have to settle for an exit row so my knees aren't in my ears. :)
 
The L-1011 was pretty cool, viewed as ahead of it's time. It was also unique in that it had a full time horizontal stabilizer (not just for trim), like most fighter aircraft.
 
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