What Happens if an Airplane’s Engines Fail?

Unlike this WW1 Sopwith Camel, a vertical crash dive down and into the ground is unlikely to happen – your plane can safely glide down to land if it loses power. Your problem is not so much the descent as the actual landing itself.

NOTE : This article reflects a mixture of my own opinion (most of my own flying has been in gliders) and that of senior airline pilots.  The complex issues have been simplified and due to the happily infrequent nature of such events, our guesses may or may not accurately describe any potential future scenario.  In other words, please don’t sue me if you’re subsequently killed in a plane crash!

The good news – it is exceedingly rare for a plane to lose power in all engines, which (along with the better economy enjoyed by two-engined planes compared to four engined planes) is offered up as a reason for reducing the number of engines on planes, and allowing them to fly further away from airports on over the water routes.

The even better news – if a plane does lose engine power, while cruising at normal speed and altitude, you’re probably going to land safely – assuming there’s somewhere moderately level and unobstructed for the plane to land.

What Might Cause Jet Engines to Fail

Modern jet engines are incredibly reliable. Add to their designed reliability the high quality of regularly scheduled maintenance, and there are very few times when an in-flight problem occurs. In addition, modern engines automatically monitor themselves, conducting computerized self-diagnostics and analyzing their actual performance while in flight, and automatically radioing ahead to an engineering base if it thinks something is not fully perfect. Occasionally a plane will land and be greeted by maintenance engineers – the pilot will ask ‘Why are you here’ and will be told ‘Your number three engine’s computer advised us that we need to check its second stage bearings’ – something the two pilots didn’t even realize was an issue!

However, nothing is infallible. Occasionally the turbine blades might break. Another source of turbine fan damage comes from ingesting foreign materials – either something loose on the ground or (quite common) a bird.

Then there may be some type of external problem that affects the engine – something might go wrong with the electrics or the fuel or lubrication or even air supply. The fuel might contain impurities that damage the engine, or the plane might simply run out of fuel. And, in one famous situation, a plane flying through the plume from an erupting volcano lost power in all its engines due to the impurities in the air.

Most problems that can occur typically affect only one engine. And any modern two or three engined passenger plane can operate more or less normally on only one engine for an extended period of time (ie for some hours). A four engined plane will work happily on two engines, but with only one engine it becomes a sort of ‘super long range glider’.

How Common is it for a Plane to Lose Power in All Engines

Very uncommon. This might happen, somewhere in the world, no more often than once every 5 – 10 years.

Losing Power in Some but not all Engines

This sometimes happens, and the chances are that you’ll probably never even know that it has occurred (on a four engined plane).

Of course, while you might not know anything about the loss of power in an engine, for sure the pilots on the flight deck are very aware of such a situation. If they can’t restart the engine and assure themselves that the problem is resolved, they may divert the plane and land it at a nearby airport. They’ll probably not urgently land the plane at the first airstrip they find, but instead will selectively choose an airport with a suitable runway, and hopefully with both engineering and emergency services available.

In such a case, the airport fire department will probably deploy just in case something else goes badly wrong at the last minute, but that is nothing to worry about. The typical airport fireman must lead an incredibly boring life – most of them will serve their entire lives without a single real full scale emergency!

Note the the use of the phrase ‘they may divert the plane’.  There was a case a couple of years ago where a BA 747 lost power in an engine shortly after taking off from Los Angeles.  Rather than return the plane back to LAX, the pilots – with BA’s approval – chose to fly the plane all the way to London, including going over the polar route where at times the nearest normal airport was somewhat distant.

Many commentators felt this to be inappropriate, but the plane had no further problems – apart from running out of fuel and having to land short of London, in Manchester.  Strangely, a plane burns more fuel flying on three engines than four in a case like this – it has to fly at a lower altitude and the greater air friction increases the fuel burn rate.

Losing Power in All Engines

The pilots don’t have much choice if they lose power in all engines.  They’re for sure going to have to land the plane.  But don’t panic (and your pilots won’t be panicking either). Statistically you have a very good chance of surviving such a situation.

If a plane loses all power, it does not then fall out of the sky. Instead it becomes a very big and rather clumsy glider, but it has the same controllability as with engines, although perhaps not quite as readily as before. It can still maneuver left and right, and can also vary its rate of descent, but it no longer can go up or stay flying level.

A plane can land without needing to use its engines. Gliders (sailplanes) do it all the time, and there is no reason why a passenger jet can not land without engine power as well.

Modern jets don’t have sufficient batteries to supply power to the plane’s hydraulics and control systems in the event of engine failure. However, an air driven generator will deploy into the airstream, and the air passing through its blades will spin this generator, enabling it to create some limited emergency power.

It is likely that the plane’s cabin pressurization will also fail. This would be a gradual failure, and then you’d get to see the oxygen masks dropping down in front of you. There is ten to fifteen minutes of oxygen supply through this system, and by the time it was used up, the pilot will have smoothly glided the plane down to below 15,000 ft, at which point you’ll no longer need the breathing masks.

Power loss while taking off

This is the worst case scenario. All modern planes can continue their take-off procedure with the loss of one engine (even if they only had two engines to start with) but if they lose all power in all engines, then the pilot has very little time or opportunity to urgently turn the plane around and to return back to the airport. Worse still, in many cases there is nowhere immediately ahead of the plane to safely land – just city.

For smaller (more maneuverable) twin-jets (eg 737s and A319s), after probably five minutes of flying, there is a good chance that the pilot can turn the plane around and land it back on the runway he took off from. However, even this is not always as simple as it sounds – in conditions of poor visibility, for example, it may not be easy to urgently get a visual fix on where the runway is!

For a large less maneuverable and fully loaded 747, keep your fingers crossed for perhaps ten minutes.

Power loss while landing

This can also present as a problem, due to the way that planes land at most airports. The plane doesn’t have (and doesn’t want!) any ‘spare’ energy (in the form of either excess height or speed) during the final five minutes or so of its landing, and a sudden loss of power two or three minutes out from touchdown will probably require the pilot to attempt to land somewhere short of the runway.

Power loss while cruising

If the plane loses all power while at cruise altitude, the first thing the pilot needs to do is to realize that he has irrevocably lost power and to switch his focus from trying to recover power to planning how and where to land. It can take a minute or two for this realization to dawn, but pilots are required, as policy, to immediately assume the worst – while still, of course, doing all they can to bring about the best possible outcome.

He should then climb steeply so as to convert the extra forward speed into extra height. The higher the plane gets, the less air resistance, the slower it will be flying, and the more range it will have. The pilot will probably get another thousand or two feet of altitude before the plane slows down to its most efficient glide speed, which is somewhere between 200-225 mph.

So, there you are, in a plane at, say, 35,000 ft, with no power. Your plane can probably travel ten to twelve times as far in a forward direction as it has height to lose – so at 35,000 ft, the plane can go about 85 miles, maybe more.

The plane will also have about 20 minutes of flying time before the altimeter reaches zero.

Which then leads to a very big question – is there a place to land within 85 miles of where the power loss occurred? When you keep in mind that this gives the pilot not just 85 miles of straight ahead, but also nearly as much travel to each side, and perhaps 70 miles back the way he came, that gives him almost 20,000 square miles of territory in which to hope to find an airport.

In most of the US, there’s a good chance that there will be an airport within that area.

Non-Airport Landings

A 757 that landed in Costa Brava, Spain, during a storm in 1999. All 233 people on board survived.

A modern jet plane needs a mile or even two of runway to land on. They typically land at about 130-160 mph, and need this distance first of all so that they can land within a broad zone of the ideal spot to touch down, and then secondly, they need the distance to brake and stop.

Although modern jets have ‘reversers’ on their engines that most pilots like to use to help slowing down, they aren’t very effective, and are not essential. The main way that the pilot slows the plane down is very simple – he steps on the brake pedal.  Actually, these days, to be more precise, he sets a little lever to low, medium, full or auto braking, then watches the plane’s autopilot do the braking for him.

An airport runway has three essential characteristics (plus other not quite so important features). The three essential characteristics of a suitable runway are :

  • It is straight and flat

  • It is long (ideally a mile or more in length)

  • It is strong, able to support the massive weight of a passenger plane supported on only three sets of wheels

  • It is well lit to help the pilot’s visual approach (and probably has electronic landing aids as well)

If a pilot can’t find an airport runway with these characteristics, he then starts looking for the next best thing. This is almost certainly not a length of freeway, unless he is able to coordinate with the highway patrol to clear a couple of miles of freeway for him to land on (almost certainly impossible with the limited time available).

There are two types of non-airport landings. In both cases, the pilot will try to land as absolutely slowly as possible – instead of a normal landing speed of 130-160 mph, if he can lower the flaps, he’ll probably be able to bring the speed down to as little as 115 mph (even the small seeming reduction in speed from 160 mph to 115 mph will halve the plane’s kinetic energy and ability to do damage to itself and its passengers).

He’ll also be dumping fuel (if this is possible with the reduced power the plane now has), not only to reduce the danger of fire upon landing but also to reduce the weight of the plane. Less weight makes it easier to land on a less strong surface, allows it to land at a slower speed, and gives the plane less momentum (at any speed), making it easier to stop.

Not an airport, not a runway, but still on land

This is difficult, but not as difficult as it might first seem.

Logically, the plane is either over a developed urban area, which reasonably implies the presence of an airport nearby, or alternatively, it is over undeveloped area, which hopefully means open fields (but not mountains!). Even if the plane is flying over a mountain range, the chances are that within its 85 mile radius of remaining flight (assuming it was at reasonable altitude to start with), it will be able to find an area of flat ground.

The landing will be rough, for sure. The pilot will probably try and keep the nose up in the air as long as possible, but then it is going to come down with a sudden thud. The undercarriage will almost certainly break off , and then the engines will be ripped off the wings, leaving the remains of the plane fuselage and wings to slide over the ground and perhaps spin around before coming to a stop. You’ll be shaken violently every which way, but if nothing bad happens, the plane will gradually come to a stop, and hopefully with no fires breaking out. If you survive the first 30 seconds of the landing, you’re probably going to be okay.

At sea

Who hasn’t looked at the life jacket or ‘flotation device’ part of the flight attendants’ safety demonstration and laughed cynically about surviving long enough to need such things ‘in the event of a water landing’?

Well, the news is basically good. There have been a number of cases where passenger jets landed in the sea, and even in the case of a ‘bad’ water landing (the pilot dropped a wing into the water too soon, causing the plane to cartwheel and break up) there was still an almost 30% survivor rate.

If you remember back to the four characteristics of an ideal runway, water actually possesses hopefully two of them. It is straight and flat (assuming that it is calm – waves will complicate things) and long.

As everyone knows who has hit water at speed, it is surprisingly unyielding at speed, but this doesn’t equate to the ‘strong’ characteristic – it won’t support the weight of the plane on its undercarriage, indeed, the pilot will probably choose to land the plane with the undercarriage up.

When the plane first hits the water it might skip, like a stone bouncing along a pond. Or, it might nose down and tunnel into the water. If it does this, don’t worry. It will quickly lose speed and then rapidly rise back to the surface before too much water enters the plane.

Assuming the main fuselage is reasonably intact, the plane would probably float on the water for long enough for the passengers to get out the emergency exits and into the life-rafts. The plane can be completely evacuated in 3 – 5 minutes.

The US Airways A320 landing in the Hudson River, 15 January 2009

An A320 shortly after it landed in the Hudson River, New York, on 15 January in the mid afternoon. All 155 people on board survived, and some didn’t even get wet.

This is a very relevant and recent example of a modern jet making a water landing.  The flight had just taken off from La Guardia when it hit a flock of birds (believed to be geese) and apparently lost power in both engines.

The pilot wasn’t in a position to allow him to turn and return to La Guardia, or to fly to any other airport, so he chose to land on the Hudson River near mid-town Manhattan, less than five minutes after taking off.

The landing was reasonably smooth, and the plane didn’t break up.  The plane was completely full with 150 passengers, three flight attendants and two pilots, and everyone was able to safely make their way to the over-wing and front exits and get off the plane.  The plane slowly settled, tail first (this is typically what you’d expect in a water landing); many of the passengers waited on the wing for the rescue boats, which were on the scene extremely quickly, to take them off; others boarded liferafts.

Summary and Reference

  • The chances of a plane losing power in all engines is very close to zero.

  • If a plane does lose power in all engines, it can probably glide to a regular airport and land safely there.

  • If there isn’t a suitable airport close enough, then your chances of surviving a landing either at sea or in the best approximation to a runway that the pilot can find are better than 50:50 in your favor.

  • Daytime landings, at places other than airports, are easier than nighttime landings.

This site has interesting information on past water landings and what happened in each case.

This site gives details of a 767 that ran out of fuel in Canada in 1983 (colloquially known as ‘the Gimli Glider’). And these two sites (here and here) give details of an Airbus A330 that glided to a landing in the Azores.

Lastly, a Joke

Paddy and Seamus were flying from Boston to Dublin on a 747. Half way across the Atlantic, there was a loud noise outside the plane – one of the engines fell off the wing.

A short while later the captain announced ‘Ladies and gentlemen, we’re very sorry to advise that we have lost one of our engines. However, there is no need to worry – the plane can fly perfectly safely on three engines. However, because we now have one less engine, we’re unable to fly quite so fast, and we estimate that we’ll now be approximately 45 minutes late arriving into Dublin.’

Seamus nodded to Paddy, and they each calmly ordered another Bushmills.

The flight continued, then all of a sudden, the plane lurched sharply to the left, then straightened up again. Paddy looked out the window, and saw flames streaming out of one of the two engines on that wing. After a minute or two, the flames died out.

The captain made another announcement. ‘Ah, sorry about that, but we’ve just had a fire break out in one of our three remaining engines. Fortunately, the fire extinguishing system worked perfectly, but of course we’ve had to shut that engine down. Don’t worry – we still have two perfectly good engines, and the plane is continuing safely. So as not to overstress the two remaining engines, we’re cutting back our cruise speed, and estimate that we’ll now be about two hours late arriving into Dublin’.

Seamus and Paddy looked anxiously at their watches, then relaxed and ordered another Bushmills.

Well, bad things happen in threes. Half an hour later, Paddy said to Seamus ‘Did you hear that – the engines sound different?’. They discussed what that might mean for several minutes, and then the Captain’s voice came over the announcement system again.

‘Ah, ladies and gentleman, I don’t quite know how to tell you this, but we’ve had a problem with another engine. We’ve had to shut it down, but, if my math is correct, that still leaves us with one perfectly good engine, and I promise you we’re going to look after that one very carefully, all the rest of the way to Dublin. We’ll probably now be about three or four hours late.’

Seamus looked at his watch, calculated when they would now be arriving into Dublin, and said to Paddy ‘We’re running very late already. I sure hope we don’t lose the last engine or else we’ll be up here all day’.

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