Air Travel » Air Travel Flight » How do you land a jet plane without engine power
Question:
- Hide quoted text — Show quoted text -> I always thought there was a "coast" ratio, that if a plane lost power >it > would coast 16 or 20 times the altitude. If a plane was at 42,000 ft, >it > could reach 840,000 feet before landing. > Karl >It’s called glide ratio, and it is typically 8 or 9 to 1.
Larry, The lift to drag ratio (L/D) of jet airliners ranges from around 15-1 to 18-1. This should give an engines-out glide distance of over 100 statute miles. Mike Lechnar Aircraft Performance Engineer "If I was speaking for Boeing, I wouldn’t be doing it here."
Response:
> The lift to drag ratio (L/D) of jet airliners ranges from around 15-1 to 18-1. > This should give an engines-out glide distance of over 100 statute miles.
You’re assuming that the aircraft doesn’t need to turn, or manouevre in any way… which it usually has to do at the *end* of its glide, where there’s no room for height-loss… — regards, Ianp http://www.darktower.com/ "If at first you don’t succeed, skydiving’s not for you!"
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- Hide quoted text — Show quoted text -> The lift to drag ratio (L/D) of jet airliners ranges from around 15-1 to 18-1. > This should give an engines-out glide distance of over 100 statute miles. >You’re assuming that the aircraft doesn’t need to turn, or manouevre >in any way… which it usually has to do at the *end* of its glide, where >there’s no room for height-loss… >– >regards, >Ianp > http://www.darktower.com/ >"If at first you don’t succeed, skydiving’s not for you!"
OK. I will concede that, in practical terms, a no engine landing requires a well trained flight crew and probably more than a little luck. But if you have to do it, 35,000 ft leaves you a lot more time to find and airport and align with the runway well before you would normally. Mike Lechnar Aircraft Performance Engineer "If I was speaking for Boeing, I wouldn’t be doing it here".
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> > The lift to drag ratio (L/D) of jet airliners ranges from around 15-1 to 18-1. > This should give an engines-out glide distance of over 100 statute miles. > You’re assuming that the aircraft doesn’t need to turn, or manouevre > in any way… which it usually has to do at the *end* of its glide, where > there’s no room for height-loss… > —
As a glider pilot I much disagree. The ability to take a transport-class aircraft to a successful landing without power is, like in a glider, based on on well you plan your flight and how well you conserve resources (in this case, altitude). True, a turn uses more energy than straight-and-level flight, but gliders turn as well as aircraft with power, and fly a normal pattern at the airport just like any other aircraft. Recall the infamous Air Canada 767 event in the 1980s–one of the flight crew was a glider pilot and that played a significant role in their successful "dead-stick" landing.
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Just as an extreme example of what can be done without power, the US Space Shuttle lands without power on every return from space.
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> Just as an extreme example of what can be done without power, the US Space > Shuttle lands without power on every return from space.
Yes, and compared to a commercial jetliner, the space shuttle barely has wings and truly does << drop like a rock .>> C. Marin Faure author, Flying a Floatplane
Response:
> I always thought there was a "coast" ratio, that if a plane lost power it > would coast 16 or 20 times the altitude. If a plane was at 42,000 ft, it > could reach 840,000 feet before landing. > Karl
It’s called glide ratio, and it is typically 8 or 9 to 1.
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> Nice in theory but if you’ve lost engines you likely have other very > serious problems happening. Lost of hydraulics for flaps, rudders as > well as electrical outages effecting radio, nav/HSI, etc.
The current generation of ETOPS jetliners (757, 767, 777, A-330), and (I think) A-340 have RATs, Ram Air Turbines, which are in essence a propeller on a strut that automatically extends from the belly of the airplane in the event of a loss of hydraulic and/or electrical power from normal sources. The RAT provides enough power to operate all the essential flight controls, landing gear, and wheel brakes. So with these airplanes, even if all the engines have shut down due to fuel starvation for example, the RAT will deploy and the plane will be completely maneuverable throughout the descent and landing. But while the RAT is the final defence, it is unlikely it would be needed outside of total fuel starvation. There is so much redundancy designed into the current generation of jetliners that the loss of even multiple levels of power and control systems will almost always leave at least one system intact. If not, there is always the RAT… C. Marin Faure author, Flying a Floatplane
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Nice in theory but if you’ve lost engines you likely have other very serious problems happening. Lost of hydraulics for flaps, rudders as well as electrical outages effecting radio, nav/HSI, etc. Ask United Airlines Captain Al Haynes about his little powered "glide" into Sioux City, IA in July of 89 when his DC-10 came to rest. Not flaming either of you, I’m just saying that perfect conditions for the glide of which you speak rarely exist. Possible, not likely. – Hide quoted text — Show quoted text – >Yeap it’s called the glide ratio for every feet forward you move you will >lose some feet in altitude. The highest glide ration are in gliders, >hence the name. >Happy Flying > I always thought there was a "coast" ratio, that if a plane lost power it > would coast 16 or 20 times the altitude. If a plane was at 42,000 ft, it > could reach 840,000 feet before landing. > Karl
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>Yeap it’s called the glide ratio for every feet forward you move you will >lose some feet in altitude. The highest glide ration are in gliders, >hence the name. > I always thought there was a "coast" ratio, that if a plane lost power it > would coast 16 or 20 times the altitude. If a plane was at 42,000 ft, it > could reach 840,000 feet before landing.
My god, they’d have to watch out for the Space Shuttle! 
— Scotty Steve Howie | **Remove the .foo when replying** NetNews and Listserv Admin. | (519) 824-4120 x2556
Response:
I always thought there was a "coast" ratio, that if a plane lost power it would coast 16 or 20 times the altitude. If a plane was at 42,000 ft, it could reach 840,000 feet before landing. Karl
Response:
Yeap it’s called the glide ratio for every feet forward you move you will lose some feet in altitude. The highest glide ration are in gliders, hence the name. Happy Flying – Hide quoted text — Show quoted text -> I always thought there was a "coast" ratio, that if a plane lost power it > would coast 16 or 20 times the altitude. If a plane was at 42,000 ft, it > could reach 840,000 feet before landing. > Karl
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|> > |> > |> > >The crash of the hijacked plane in the Indian Ocean made me think how you |> > >can land a jetliner without engine power. |> > |> > >I know they can glide and do not drop from the sky like a stone when all |> > >engines fail or they are out of fuel. |> > |> > >Luidger |> > |> > In the eighties an Air Canada Boeing 767 ran out of fuel (they |> > did not put enough while refueling and the gauges were not working |> > properly). The pilot, who had gliding experience, was able to glide |> > to an abandoned runway and land safely. The idea is to make gravity |> > maintain the proper air speed of the aircraft, i.e. the plane must |> > come down within a specific angle range. Since the pilot had no power |> > available (except a small generator for radio use), he was not able to |> > use wing flaps while landing. They made a TV movie about it. You will |> > enjoy it!!! |> > |> > Rafal. |> Rafal — PMFJI, but CNN showed an amateur video of the crash today. Top |> quality video, and a real testament to the skill of the pilot. |> A testament to the pilot’s skill if he was struggling with hijackers or if he had lost hydaulics, otherwise he made a big mistake landing with wings not level. — Colin A R Beveridge Microelectronic Engineering The University of Edinburgh United Kingdom http://www.ed.ac.uk
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>Rafal — PMFJI, but CNN showed an amateur video of the crash today. Top >quality video, and a real testament to the skill of the pilot. >Craig
Hmm, well when the plane was approaching the water, it looked like it was rolled about 15 degrees to the left. As a result the left wingtip contacted the water first, probably ripping the wing off (hard to see among the spray) and causing _extensive_ damage to the aeroplane and consequent loss of lift. I thought it was a poor landing and the pilot should have landed with wings level. The (relatively few) water ditchings generally work out a lot better than this, with most/all of the passengers surviving, probably because the plane ditches with the wings level. Joshua Boyd or
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|> The crash of the hijacked plane in the Indian Ocean made me think how you |> can land a jetliner without engine power. |> |> I know they can glide and do not drop from the sky like a stone when all |> engines fail or they are out of fuel. |> |> From my experience as an air traveler, I know that in the beginning of the |> sinking phase the engines are pretty much on idle, but during the final |> approach when the flaps are extended to the maximal degree, the engines |> push again pretty much (according to noise levels in the cabine). If you |> do not have engine power, does that mean you land the plan without the |> help lift enhancing device like flaps? This would mean the plane has to |> touch down with higher speed. But how do you brake it without reverse |> thrust? Only by the wheel brakes? |> |> A confused air traveler would appreciate the experts opinion on this issue. The other answers you have received are correct. Any aircraft can glide to a safe landing. When making a "normal" landing, the aircraft deploys full flaps, which introduces considerable drag. The higher engine speed is required to overcome this drag. The full flaps allow landing at a lower speed. The second reason to land at high throttle is to be prepared for a missed approach or a go-around. Jet engines take several seconds to respond to changes in throttle, so landing at close to full throttle allows the pilot to abort the landing up to the moment of touchdown without having to wait for the engines to spool up again (if, for example, another aircraft taxis onto the active runway).
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I looked at the video on a frame by frame basis (downloaded to my MAC, about 14 seconds 32 meg !) of the ethiopian water "landing". The left wing *TIP* touched the water for a "long" while in a fairly stable way. Then, the plane started to level out with the rest of the plane dropping a bit. As the left engine touched water, the water spray started to obscure the scene left of the plane but I did see debris fly out (up) almost immediatly. Then the fuselage touched the water, but the right wing started to rise (eg: plane started to bank left again). I *assume* that the right wing still provided some lift at that time. Right engine didn’t touch water. The plane then started a 90 degree spin counter-clockwise (imagine the left side of plane with perhaps part of left wing well inside the water was dragging more than the right side). During that rotation, the left bank increased to a point where the right wing was vertical (you could see it stand out of the water sray for a while). After that the whole thing was hidded by the water spray. The final picture showed the tail sticking out of the water, indicating that at least the rear of the plane had finished the landing cycle upside. Very interesting piece of video. I thik Boeing will want to get its hands on it ! The pilot was interviewed and did state that the highjackers started to fight him as soon as they realised he was trying to land. I am not sure when engine power was cut. But from the look of the crash and the lack of water spray near the right engine, I’d venture to say that both engines were cut off prior to the landing.
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>>Rafal — PMFJI, but CNN showed an amateur video of the crash today. Top >quality video, and a real testament to the skill of the pilot. >Craig > Hmm, well when the plane was approaching the water, it looked >like it was rolled about 15 degrees to the left. As a result the >left wingtip contacted the water first, probably ripping the wing >off (hard to see among the spray) and causing _extensive_ damage >to the aeroplane and consequent loss of lift. I thought it was >a poor landing and the pilot should have landed with wings level.
Well, with a pair of drunken lunatics armed with a fire axe standing over you, and no thrust left in the engines, I think it’s asking a bit much to expect a perfectly level contact with the water, given that the pilot has one chance and one chance only to land. I’m not even sure the auxiliary power available from the RAT (if it deployed) would have given enough oomph to allow the pilot to handle the control surfaces properly. Give the poor guy a break – he did *remarkably* well under the circumstances. >The (relatively few) water ditchings generally work out a lot >better than this, with most/all of the passengers surviving, >probably because the plane ditches with the wings level.
So, assuming the wings were level, what happens when the leading edge of the engine nacelles hit the water? Face plant! -> damage. — Scotty Steve Howie | **Remove the .foo when replying** NetNews and Listserv Admin. | (519) 824-4120 x2556
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|> The crash of the hijacked plane in the Indian Ocean made me think how you |> can land a jetliner without engine power. |> |> I know they can glide and do not drop from the sky like a stone when all |> engines fail or they are out of fuel. |> |> From my experience as an air traveler, I know that in the beginning of the |> sinking phase the engines are pretty much on idle, but during the final |> approach when the flaps are extended to the maximal degree, the engines |> push again pretty much (according to noise levels in the cabine). If you |> do not have engine power, does that mean you land the plan without the |> help lift enhancing device like flaps? This would mean the plane has to |> touch down with higher speed. But how do you brake it without reverse |> thrust? Only by the wheel brakes? |> |> A confused air traveler would appreciate the experts opinion on this issue. You don’t sound very confused at all! Everything you say is correct, the plane must be flown in a clean configuration (no flaps or gear) and that means a high touchdown speed. Some flaps will probably be used, and the gear will be dropped (not for a water landing) late on. Brakes and aerodynamic braking will be used and will probably be enough. Another reason for maintaining a high approach speed is that power comes from a wind generator which is deployed in emergencies, and it needs enough speed to work. Below, I think, 250knots, it is useless and you then have only 30 minutes of battery power to finish the landing. In the case of the water landing, the primary requirement is wings level! It is also important, when choosing the direction of landing, to consider the tide and swell, and not to flare but to fly into the water with only a very slight pitch up. That was not achieved in the latest incident and the result was a cartwheel with loss of structural integrity. Furthermore, if you’ve seen the video, note that most pax haven’t done up the straps on the life vests, even though they have put them on… — Colin A R Beveridge Microelectronic Engineering The University of Edinburgh United Kingdom http://www.ed.ac.uk
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>A modern "heavy" has most of the gliding characteristics of a rock… >they need a fair amount of aipseed to maintain any kind of controllable >flight. Without engines, the only way to sustain the speed is *down*… >a very steep glide angle, almost a controlled plummet, in fact. >IMHO, the pilot involved in that crash did an amazing job in even managing >to crash in roughly the right place (on water, close to the beach) >with no power, no auxiliaries, very little assisted control and no >margin for error.
I don’t know, I’ve heard a rule of thumb for most larger jets that you begin an idle power (no real thrust out of the engine) at 3 times the number of thousands of feet + about 20 NM from your destination. In other words if you are at a normal 35000 feet that works out to 35 X 3 + 20 or 125 Nautical Miles from the destination. I realize that when they ‘dirty up’ the wings with flaps, they usually land with something like 60-75% power, but, that is in the last few miles of the descent and I’ve heard of and been on flights where power before landing was used only very little. I therefore have a problem with the term ‘very steep glide angle’. Also, unless you run out of fuel there is an APU (Auxiliary Power Unit) which generates electricity and hydraulic power when necessary that provides for control surface assist or motion (depending on the design of the AC). Misinformation and twisted facts are really bad things! Chris Jardine CJ Electronics http://www.wctc.net/~cjardine/
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> The crash of the hijacked plane in the Indian Ocean made me think how you > can land a jetliner without engine power. > I know they can glide and do not drop from the sky like a stone when all > engines fail or they are out of fuel. > From my experience as an air traveler, I know that in the beginning of the > sinking phase the engines are pretty much on idle, but during the final > approach when the flaps are extended to the maximal degree, the engines > push again pretty much (according to noise levels in the cabine). If you > do not have engine power, does that mean you land the plan without the > help lift enhancing device like flaps? This would mean the plane has to > touch down with higher speed. But how do you brake it without reverse > thrust? Only by the wheel brakes?
Modern jetliners like the 757, 767, 777, A-320 and A-330 have RATS- Ram Air Turbines- which are essentially small propellers on a strut that pop out of the belly into the airstream if all hydraulic and/or electrical power is lost from the engine sources, which would include running out of fuel. The propeller turns a hydraulic pump and/or a generator which provides enough power to operate the necessary flight controls. So the pilot of one of these planes which had run out of fuel would still have the necessary hydraulic/electrical power to fly the plane under full control to the safest possbible touchdown. If the landing is on a runway, the wheel brakes will operate, but without reverse thrust from the engines, it will be a VERY long landing rollout with the possibility of running off the end of the runway. And contrary to popular belief, modern jetliners do not "drop like a stone" if the engines are all shut off or pulled to idle. The long wings we (the manufacturers) use to increase fuel efficiency also increase the airplane’s glide capabilities. They can go a lot farther without power than most people think, and they are fully controllable during the glide and landing. C. Marin Faure author, Flying a Floatplane
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- Hide quoted text — Show quoted text ->The crash of the hijacked plane in the Indian Ocean made me think how you >can land a jetliner without engine power. >From my experience as an air traveler, I know that in the beginning of the >sinking phase the engines are pretty much on idle, but during the final >approach when the flaps are extended to the maximal degree, the engines >push again pretty much (according to noise levels in the cabine). If you >do not have engine power, does that mean you land the plan without the >help lift enhancing device like flaps? This would mean the plane has to >touch down with higher speed. But how do you brake it without reverse >thrust? Only by the wheel brakes?
One of the very first things a pilot learns (in a single engine Cessna or similar aircraft) is how to deal with an engine out emergency. At least in Cessna’s (what I fly) the procedure is to set up the airplane for its most efficient glide profile, only applying flaps and other drag-inducing devices when assured of making the runway (or field, highway, whatever.) As for braking, most planes, including many jets, only use wheel brakes for slowdown. This may not be ideal, but with no power, your landing options are limited and the goal is to salvage the situation as best you can. —
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- Hide quoted text — Show quoted text ->The crash of the hijacked plane in the Indian Ocean made me think how you >can land a jetliner without engine power. >I know they can glide and do not drop from the sky like a stone when all >engines fail or they are out of fuel. >Luidger > In the eighties an Air Canada Boeing 767 ran out of fuel (they > did not put enough while refueling and the gauges were not working > properly). The pilot, who had gliding experience, was able to glide > to an abandoned runway and land safely. The idea is to make gravity > maintain the proper air speed of the aircraft, i.e. the plane must > come down within a specific angle range. Since the pilot had no power > available (except a small generator for radio use), he was not able to > use wing flaps while landing. They made a TV movie about it. You will > enjoy it!!! > Rafal.
Rafal — PMFJI, but CNN showed an amateur video of the crash today. Top quality video, and a real testament to the skill of the pilot. Craig
Response:
> I know they can glide and do not drop from the sky like a stone when all > engines fail or they are out of fuel.
A modern "heavy" has most of the gliding characteristics of a rock… they need a fair amount of aipseed to maintain any kind of controllable flight. Without engines, the only way to sustain the speed is *down*… a very steep glide angle, almost a controlled plummet, in fact. IMHO, the pilot involved in that crash did an amazing job in even managing to crash in roughly the right place (on water, close to the beach) with no power, no auxiliaries, very little assisted control and no margin for error. > From my experience as an air traveler, I know that in the beginning of the > sinking phase the engines are pretty much on idle, but during the final > approach when the flaps are extended to the maximal degree, the engines > push again pretty much (according to noise levels in the cabine). If you > do not have engine power, does that mean you land the plan without the > help lift enhancing device like flaps? This would mean the plane has to > touch down with higher speed. But how do you brake it without reverse > thrust? Only by the wheel brakes?
In the case of a water landing, standard practise is to land with the gear up… the water stops you fast enough… If a pilot has managed to make a dead-stick landing on his wheels, then stopping is easy – once the ground-speed is low enough, he can use wheel breaks – provided there’s still power for them. If not, running off the end of the runway is generally quite effective… — regards, Ianp http://www.darktower.com/ "Suddenly, and without warning, there was this Total Eclipse Of The Sun"
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>The crash of the hijacked plane in the Indian Ocean made me think how you >can land a jetliner without engine power. >I know they can glide and do not drop from the sky like a stone when all >engines fail or they are out of fuel. >Luidger
In the eighties an Air Canada Boeing 767 ran out of fuel (they did not put enough while refueling and the gauges were not working properly). The pilot, who had gliding experience, was able to glide to an abandoned runway and land safely. The idea is to make gravity maintain the proper air speed of the aircraft, i.e. the plane must come down within a specific angle range. Since the pilot had no power available (except a small generator for radio use), he was not able to use wing flaps while landing. They made a TV movie about it. You will enjoy it!!! Rafal.
Response:
The crash of the hijacked plane in the Indian Ocean made me think how you can land a jetliner without engine power. I know they can glide and do not drop from the sky like a stone when all engines fail or they are out of fuel. From my experience as an air traveler, I know that in the beginning of the sinking phase the engines are pretty much on idle, but during the final approach when the flaps are extended to the maximal degree, the engines push again pretty much (according to noise levels in the cabine). If you do not have engine power, does that mean you land the plan without the help lift enhancing device like flaps? This would mean the plane has to touch down with higher speed. But how do you brake it without reverse thrust? Only by the wheel brakes? A confused air traveler would appreciate the experts opinion on this issue. Fortunately, it does not happen that often. Luidger Luidger Roeckrath * office: Institut fuer Buergerliches Recht und Zivilprozessrecht Ludwig-Maximilians-Universitaet Muenchen Prof.-Huber-Platz 2, 80539 Muenchen, ph: +49 89 21802183 * web: http://www.lrz-muenchen.de/~u312202/www/homepage.htm
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