Spoilers not deployed

[alvcheng]

A few days ago, I was travelling on a 747-400 flight from London Heathrow to Hong Kong. After it touches down, I found no spoilers are being deployed. Is it normal? I have never travelled on a flight with no spoilers being delpoyed after touch down. Is it a mechanical failure or is there other reasons to explain why the pilots do not deploy the spoilers?

[ACman]

Well where were you sitting?

[RingwaySam]

A few days ago, I was travelling on a 747-400 flight from London Heathrow to Hong Kong. After it touches down, I found no spoilers are being deployed. Is it normal? I have never travelled on a flight with no spoilers being delpoyed after touch down. Is it a mechanical failure or is there other reasons to explain why the pilots do not deploy the spoilers?

I suppose it depends on the weight of the aircraft etc. Were there a lot of people on-board? and did you taxi to a stand near the end of the runway?

[MaxPower]

Well where were you sitting?

:skeptic:

First class or Monkey class, does it really matter where he was sitting , if so, how ? ? ?

[ACman]

:skeptic:

First class or Monkey class, does it really matter where he was sitting , if so, how ? ? ?

It does.

You know about optical deceptions right?

Well there are seats on certain aircraft forward of the wing that when the spoilers get deployed it looks like nothing has happend.

Where ever you are and watever your facing has an effect on what seeing.

[MaxPower]

^^You got a point there, I didnt know you were referring to the visual deception.

And by my previous post, I meant that it wouldnt matter where he was sitting though, as mechanical failure or not, the plane would give a cr@p where that passenger was sitting. But I get what you mean.

Btw What was the aircrafts landing weight at that time ? If AL Cheng can get it or anyone else, might solve it.

[AJ]

Shouldn't matter, spoilers should be deployed on all 747 landings, whether by the auto-speedbrake system or manually if it is not servicable.

[FlyingPhotog]

Shouldn't matter, spoilers should be deployed on all 747 landings, whether by the auto-speedbrake system or manually if it is not servicable.

Out of curiosity, how long would it take to manually deploy a 747's spoilers?

[ACman]

Out of curiosity, how long would it take to manually deploy a 747's spoilers?

Manual Deploy is when you move the spoiler lever yourself, instead of setting it to Auto.

[FlyingPhotog]

Manual Deploy is when you move the spoiler lever yourself, instead of setting it to Auto.

You mean they don't go out on the wing and lift it by hand? :lol: So it's just a switch you move? I see. So it only would take a couple seconds then. I didn't know if it was a botton, or a crank or what.

[MaxPower]

Capt to F/O *Oh Charlie, Its not working.. Can you please go out on the wiing and crank it out ?* :lol:

[YYZPICS]

Im pretty sure its a crank?

[alvcheng]

At that time, I am sitting at the back of the plane. The plane is full of passengers. The fuel tank should be quite empty after a long flight, so the plane should not be too heavy.

Before touchdown, I did see spoilers being deployed to slow the airplane down, so optical deceptions is not a reason. Moreover, I found that reverse thrust is also not being used.

Is the use of spoilers a must for a 747 during touchdown?

[G-DALE]

Out of curiosity, how long would it take to manually deploy a 747's spoilers?
Simply pull the lever out from the 'Down' position, then move it into the 'Up' position.

You can clearly see the lever on the left here -

[photoid=409139]
Before touchdown, I did see spoilers being deployed to slow the airplane down, so optical deceptions is not a reason.
When you say "before touchdown," do you mean whilst on descent or literally seconds before touchdown? If this happened a few seconds before touchdown then it's more than likely that the PIC (pilot in command) was making a few final corrections using the roll ailerons (on the surface of the wings), which are the spoilers and fully deploy when the aircraft has touched down on the runway.

Hope that helps,

Dale

[Foxtrot]

You know, this topic just reminded me of a similar instance. I was in a DL
L 1011-500 on a flight from ATL to FRA back in 1993. Just after touchdown at FRA, I distinctly remember the spoilers not deploying. Flaps were fully deployed. The reverse thrust was also loud, but no spoilers. I was sitting in one of the last ten rows behind the wing, where I had a clear view of the flaps and everything, so I should've seen the spoilers come up but I didn't.

Going to the 744, there are some things I'd like to say. The spoilers should deploy regardless of what the plane's weight is, but as I just said, the
L 1011's spoilers didn't deploy at all when it landed (the one I was in i.e.). So I can believe that. Also, only if you're in the front first/business class cabin forward of the first door might you not see the spoilers being deployed. Otherwise, it shouldn't matter, you should be able to see the spoilers going up, they're not that small.

As for reverse thrust not being used, hmm, that's strange, it might be that the pilots just deployed the doors and let the engines idle to slow the plane down.

[alvcheng]

I mean I see spoilers being deployed whilst on descent, not a few seconds before touchdown.

I think a 747 can still land sucessfully by using the auto-brakes only. The runway in Hong Kong has a length of 3800m.

Also, I remember the captain mention something about fast approach. I guess the pilot is trying to slow the plane to taxi speed just before the plane reach the high speed taxiway so that the runway can be cleared quickly. Maybe that is the reason they don't use spoilers.

[G-DALE]

I mean I see spoilers being deployed whilst on descent, not a few seconds before touchdown.

I think a 747 can still land sucessfully by using the auto-brakes only. The runway in Hong Kong has a length of 3800m.

Also, I remember the captain mention something about fast approach. I guess the pilot is trying to slow the plane to taxi speed just before the plane reach the high speed taxiway so that the runway can be cleared quickly. Maybe that is the reason they don't use spoilers.
Ah, that explains it then.

If the aircraft's gate is towards the end of the runway then there's not much point in vacating early, so they'll often keep it rolling to the last taxiway, thus there's not as much of a hurry in stopping.

Alternatively you can touchdown towards the middle of the runway, then apply spoilers and reversers etc.

Cheers,

Dale

[YYZPICS]

747's can stop pretty fast..

A normal arrival on 33L

[photoid=5682767]

A 774 half way down the rwy(33L)
http://www.jetphotos.net/user-uploads/yyzhf744arrival.jpg

[G-DALE]

747's can stop pretty fast..
Yes.... With spoilers and reversers deployed ;)

[MaxPower]

Yes.... With spoilers and reversers deployed ;)

How about without them reversers and spoilers, how much of a 3800m runway will it have to use before it is at deadstop ? Just curious if you happened to kow that as well.


Thanks

[AJ]

Ah, that explains it then.

If the aircraft's gate is towards the end of the runway then there's not much point in vacating early, so they'll often keep it rolling to the last taxiway, thus there's not as much of a hurry in stopping.

Alternatively you can touchdown towards the middle of the runway, then apply spoilers and reversers etc.

Cheers,

Dale
Mr. Boeing would have a hernia! Roll throughs still require the speedbrake to be armed and idle reverse selected (selecting idle reverse will deploy the speedbrake even if it was not armed. The only thing that will not allow the spoiler to be deployed is if the thrust was never retarded to idle. 3,800m would not be long enough in that situation.

Most airline SOPS dictate a touchdown in the touchdown zone (prior to 2,500' in a -400). Even our Dash 8s are required to do that since the installation of QARs.

[Colin Parker]

CX definately requires speedbrakes to be used for every landing. Not only does it act as an aerodynamic block to airflow, but it pushes the weight of the aircraft down onto the breakes and wheels which helps it to stop. We most certainly do not disarm the speedbrakes even if we can roll the end end of the runway. It would be as ridiculous as landing halfway down the runway on purpose because you merely want to vacate at the end! In CX we always land in the 1000-2000ft touchdown zone. Anything outside this will earn you a fail on a flight test.

[screaming_emu]

In CX we always land in the 1000-2000ft touchdown zone. Anything outside this will earn you a fail on a flight test.

or worse

[photoid=519106]

[jmackey_YYT]

Would strong headwinds and the combination of needing to get to the opposite end of the runway to exit have any impact on the decision to do this?

[G-DALE]

It would be as ridiculous as landing halfway down the runway on purpose because you merely want to vacate at the end!
Okay, in a B747 or similar I agree, not so bad in something like a Dash 8 or an F50 though.

Dale

[Kevin]

I remember when i was in Sydney earlier this year I saw a Dash 8 touching down right on the piano key, just to vacate teh runway as quickly as possible to get to the gate (runway 16R).:wiggle:

[pkonowrocki]

Actually do the spoilers reduce the speed ?? I thought it helps the aircraft stay on the runway and not "jump" just after touchdown.
Oh and btw. 767s also can stop really fast. When I was flying to Warsaw captain set autobrakes to 3 and with reversers it stopped reallly fast. When flying something smaller, like 737, do you have to use spoilers ?

[screaming_emu]

Actually do the spoilers reduce the speed ?? I thought it helps the aircraft stay on the runway and not "jump" just after touchdown.
Oh and btw. 767s also can stop really fast. When I was flying to Warsaw captain set autobrakes to 3 and with reversers it stopped reallly fast. When flying something smaller, like 737, do you have to use spoilers ?

They do reduce the speed as well as dumping the lift as you said. Whenever you stick something up into the airstream it creates drag, especially when they're as big as spoilers are. Also, a combination of dumping the lift created by the wings, there's also a bit of downforce created, this pushes the airplane harder down onto the wheels so the wheel brakes are more effective.

[pkonowrocki]

Yeah, but when you use spoilers in the air to reduce speed, do they casue some kind of turbulence ? I was flying on A320 and pilot used spoilers on descend and except for the noise it was shaky. I would like to know if it was caused by spoilers or just the wind.

[ACman]

Yeah, but when you use spoilers in the air to reduce speed, do they casue some kind of turbulence ? I was flying on A320 and pilot used spoilers on descend and except for the noise it was shaky. I would like to know if it was caused by spoilers or just the wind.

Spoilers will do that on aircraft, it gets pretty shifty.

[MaxPower]

^^I recall being onboard on a LH321. We've just landed and not even a whole minute passed by this captain made a rapid right turn, so rapid that the seatbelt was tighten much on my stomach. It was very shaky..! How much does a A321 need down the runway before he is able to make the rapid get-away turn from the runway ???

Oh and btw. Spoilers were deployed IIRC ..

[screaming_emu]

Well, when the spoilers deploy, they separate the airflow over top of the wing which does lead to turbulent airflow behind the spoiler. This isn't a picture of the airflow behind a spoiler, but the airflow overtop of the wing is separating due to the wing being at too high an angle of attack (stalling), but none the less you can see how the airflow becomes turbulent.

http://www2.icfd.co.jp/examples/naca0012_2d/image/ma00901.jpg

In light aircraft (and probably big ones too) this turbulent airflow will hit the horizontal stabilizer and cause a bit of a turbulent feel. Actually, if you slow down to a really slow airspeed in a light aircraft, and look backwards, usually you can see the horizontal stab bouncing around quite violently. I'm not familiar with flying large aircraft yet, so I dont know if the turbulence you feel when the spoilers are deployed are from the turbulent air acting on the wing, or if it is in fact the turbulent air bouncing the horizontal stab around.