Spoiler & go arounds
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Spoiler & go arounds
Enlighten me, please, heavy metal flyers:
"Spoilers armed" checklist item means the spoilers will deploy automatically on ground contact via a main gear squat switch or similar, si?
A go around after ground contact must therefore require some nifty throwing of switches or are the spoilers disabled by some other means?
I imagine a go-around after ground contact in a plane big enough to have spoilers is a rather serious event and one would not like to be attempting it with deployed spoilers?
I think I have it wrong? Can someone advise please?
Thank you
"Spoilers armed" checklist item means the spoilers will deploy automatically on ground contact via a main gear squat switch or similar, si?
A go around after ground contact must therefore require some nifty throwing of switches or are the spoilers disabled by some other means?
I imagine a go-around after ground contact in a plane big enough to have spoilers is a rather serious event and one would not like to be attempting it with deployed spoilers?
I think I have it wrong? Can someone advise please?
Thank you
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"By design, no manufacturer is gonna let one of their shiny birds execute a go around or similar with spoilers deployed.".......You can in a Tornado! I've seen it done on a touch and go! Flew alright though.
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How far do you need to advance the throttles to retract the spoilers? Will the autospoilers disarm when you get the throttles beyond that critical point?
I'm asking, because I'm curious about what happens if you try to correct a bounced landing by applying a bit of power. In this video the spoilers apparently keep extending when the aircraft is in the air: http://www.youtube.com/watch?v=SRFtBVllxgg
I'm asking, because I'm curious about what happens if you try to correct a bounced landing by applying a bit of power. In this video the spoilers apparently keep extending when the aircraft is in the air: http://www.youtube.com/watch?v=SRFtBVllxgg
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For many reasons, a "go-around" once on the runway in a large airplane isn't necessarily a good idea. A large airplane, indeed most any turbojet airplane, isn't operated with "touch and go" landings like a light airplane might be. Many turbine airplanes can be made to go around with the boards extended. However, go arounds are really the same as missed approaches, and for the most part, boards aren't out the same time as flaps until the aircraft is on the ground. Ensuring the boards are retracted as part of any balked landing or go-around proceedure is necessary, however, automatic status not withstanding.
If the aircraft has slowed to the point of being on the runway, into reverse and spoilers auto deployed (such as bringing #1 or #4 engines into reverse, for example), attempting to reverse the configuration and go would require a pretty darn good reason. If autobrakes are used, they're probably already operating at this point. Engines would have to be brought out of reverse thrust, spooled back up evenly, the aircraft reconfigured on the roll for takeoff, braking disengaged, and the aircraft accelerated to a rotation speed again, with a good percentage of the runway already behind.
If an exigent circumstance such as a pending runway incursion occurs downfield (another aircraft taxiing or under tow entering the runway for example), one may do nothing more than increase the impact energy if one is already on the ground and slowing, when one attempts to go. A max effort stop with decreaing energy may be the best option at that point.
If the aircraft has slowed to the point of being on the runway, into reverse and spoilers auto deployed (such as bringing #1 or #4 engines into reverse, for example), attempting to reverse the configuration and go would require a pretty darn good reason. If autobrakes are used, they're probably already operating at this point. Engines would have to be brought out of reverse thrust, spooled back up evenly, the aircraft reconfigured on the roll for takeoff, braking disengaged, and the aircraft accelerated to a rotation speed again, with a good percentage of the runway already behind.
If an exigent circumstance such as a pending runway incursion occurs downfield (another aircraft taxiing or under tow entering the runway for example), one may do nothing more than increase the impact energy if one is already on the ground and slowing, when one attempts to go. A max effort stop with decreaing energy may be the best option at that point.
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I dare say it would be a safe bet to say all jets auto stow on advancing the thrust. Even the little citation I fly auto-stows on advancing the thrust levers. It actually works from the position of the thrust levers (or the trust lever angle) rather than say engine RPM.
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You'd lose that bet. The Lear 35 boards stay out so long as they're manually deployed. They'll blow down if they're high enough,but failure to retract them with the flaps deployed, such as a balked landing once the wheels are on the ground could be problematic; you can't have both boards and flaps out on that aircraft, and there's nothing automatic about them.
Perhaps you're confusing the issues of coming out of reverse with stowing spoilers.
Perhaps you're confusing the issues of coming out of reverse with stowing spoilers.
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There you go...I would lose that bet. No I'm not confusing TRs with the spoilers. Although I have not tried advancing the the Trust levers with the buckets deployed. One of [ground] checks is to manually deploy the spoilers then advance either one of the thrust levers to make sure that they auto-stow.
It seems a little unsafe of a design that if you deployed spoilers as the wheels touched, then decided to abort the landing and spool up to still have the boards out. You'd have your hands full enough already if you were 'going around' that late for whatever reason.
It seems a little unsafe of a design that if you deployed spoilers as the wheels touched, then decided to abort the landing and spool up to still have the boards out. You'd have your hands full enough already if you were 'going around' that late for whatever reason.
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This brings up the issue of low-energy go-arounds, whether with or without spoilers. In the case of our airplane (CRJ200), the thrust is brought to idle at 50' AGL. At that point the airplane enters the low-energy state. We are not expressly prohibited from, but are very strongly advised against go-arounds after that point, except in an extemely dire situation. In other words, you are commited to landing, smack it if you have to.
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During certification testing with jet transport aircraft, go-arounds with spoilers extended are done, and indeed with one type, the Lockheed L1011, it works just fine.
Is the climb gradient affected?
Of course it is, as you would expect.
Another type that does not automatically retract spoilers in the event of a go-around is the original swept-wing transport type...Boeing 707.
Spoilers are all manual operation on this type.
Now, having said this, going around once the airplane is on the runway, spoilers have been extended and possibly reverse selected is a very rare event, and sometimes it doesn't work out for the best.
An AA B727 at STT comes to mind.
Is the climb gradient affected?
Of course it is, as you would expect.
Another type that does not automatically retract spoilers in the event of a go-around is the original swept-wing transport type...Boeing 707.
Spoilers are all manual operation on this type.
Now, having said this, going around once the airplane is on the runway, spoilers have been extended and possibly reverse selected is a very rare event, and sometimes it doesn't work out for the best.
An AA B727 at STT comes to mind.
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In the case of our airplane (CRJ200), the thrust is brought to idle at 50' AGL.
I fly the B747-400 and have flown B737's and A320 family, and even in the B747 I would not dream of reducing thrust in normal circumstances until about 30' AGL, and the 747 because of its mass carries much more momentum than any of the other types I have flown, and doubtless MUCH more than the CRJ200.
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Originally Posted by TopBunk
That sounds pretty unusual and rather prescriptive imho. Is that the manufacturers advice or company SOP? What speed target do you use for 50'AGL? If Vref +5 then the flare process will surely result in touchdown at Vref minus quite a few knots. What happens in windshear, do you still retard the levers at 50'?
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I remember reading an article in 'Flying' magazine, written by 757/767 Captain Thomas Block. He wrote about one time when he was using spoilers in the descent and when it came to level off he had forgotten the speedbrakes. A gentle reminder from the right seat put things right.
He then went on to write about (I think) an American Airlines 757 that due to a navigational issue, crashed in mountainous terrain. I believe it was the subject of one of those Air Crash Investigation programmes at one time.
It was subsequently found that it had crashed during the descent phase, and recovery showed the speedbrakes were deployed at impact, although I think the CVR/FDR showed the aircraft crashed while attempting to climb. The crew had used the speedbrakes for the descent and at the time of trying to climb, did not retract the speedbrakes. I do not know whether the application of speedbrakes was fundamental to the crash or not. I guess it certainly didn't help.
His article was based upon not being able to think of a scenario when thrust and speedbrakes in combination would be desirable? And why the spoilers did not auto-retract in the air with power application like they do on the ground. Is this still the case or have systems changed since then?
EDIT: Just read Saskatoons post... he knows what I'm talking about!
He then went on to write about (I think) an American Airlines 757 that due to a navigational issue, crashed in mountainous terrain. I believe it was the subject of one of those Air Crash Investigation programmes at one time.
It was subsequently found that it had crashed during the descent phase, and recovery showed the speedbrakes were deployed at impact, although I think the CVR/FDR showed the aircraft crashed while attempting to climb. The crew had used the speedbrakes for the descent and at the time of trying to climb, did not retract the speedbrakes. I do not know whether the application of speedbrakes was fundamental to the crash or not. I guess it certainly didn't help.
His article was based upon not being able to think of a scenario when thrust and speedbrakes in combination would be desirable? And why the spoilers did not auto-retract in the air with power application like they do on the ground. Is this still the case or have systems changed since then?
EDIT: Just read Saskatoons post... he knows what I'm talking about!
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American Airlines at Cali Colombia
The details are here, aw8565...
http://www.ntsb.gov/ntsb/Response2.a...p24=Boeing+757
One would have thought that AA would have guys at the pointy end that knew better...
http://www.ntsb.gov/ntsb/Response2.a...p24=Boeing+757
One would have thought that AA would have guys at the pointy end that knew better...
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Top Bunk,
I think you will find it is pretty normal for most aircraft (if not all) to be certified to touch down at Ref minus a bit. After all, Vref is the speed at 50', not at touch down. Most types are certified, and landing figures based on, thrust levers going to idle AT 50' while the aircraft is AT Vref+0 which would result in touching down at less than Vref. Even the turboprops I have flown in the past, which have a huge amount of drag at idle, the AFM still says the technique is to go to idle at 50' at a speed of vref. I think to 'normal' retarding later, and carrying a few knots is more a thing to simply result in a smoother touchdown.
It is normal procedure for the biz jets I am flying at the moment that do not have leading edge devices to normally go to idle at 50'. The lack of leading edge devices (which is the same for the CRJ200 i believe) results in a fair bit less drag, and a much lower nose attitude than an aircraft with leading edge flaps/slats. If idle is selected later, it does want to float quite a lot.
I think you will find it is pretty normal for most aircraft (if not all) to be certified to touch down at Ref minus a bit. After all, Vref is the speed at 50', not at touch down. Most types are certified, and landing figures based on, thrust levers going to idle AT 50' while the aircraft is AT Vref+0 which would result in touching down at less than Vref. Even the turboprops I have flown in the past, which have a huge amount of drag at idle, the AFM still says the technique is to go to idle at 50' at a speed of vref. I think to 'normal' retarding later, and carrying a few knots is more a thing to simply result in a smoother touchdown.
It is normal procedure for the biz jets I am flying at the moment that do not have leading edge devices to normally go to idle at 50'. The lack of leading edge devices (which is the same for the CRJ200 i believe) results in a fair bit less drag, and a much lower nose attitude than an aircraft with leading edge flaps/slats. If idle is selected later, it does want to float quite a lot.
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I think you will find it is pretty normal for most aircraft (if not all) to be certified to touch down at Ref minus a bit. After all, Vref is the speed at 50', not at touch down. Most types are certified, and landing figures based on, thrust levers going to idle AT 50' while the aircraft is AT Vref+0 which would result in touching down at less than Vref. Even the turboprops I have flown in the past, which have a huge amount of drag at idle, the AFM still says the technique is to go to idle at 50' at a speed of vref. I think to 'normal' retarding later, and carrying a few knots is more a thing to simply result in a smoother touchdown.
I know that if you tried that in any of the types I previously mentioned, it would result in a heavy landing most of the time if flown at anything like Vref, or worse a tail strike as you try to reduce the ROD.
Having flown the 757 into numerous tricky Greek summer destinations, I can also say that the best technique is to fly the aircraft onto the touchdown point with a combination of thrust and attitude, which results in a firm but short arrival.
I have also run this past a current Airbus test pilot, his opinion is that if you chop the power at 50' in any of his company machines, you are asking for trouble.
Last edited by atyourcervix73; 2nd Apr 2007 at 17:24. Reason: Awful spelling