What happens if all the plane’s engines fail in the air?
If all the aircraft’s engines fail, will the plane still fly or will it fall out of the sky?
Can a plane fly if all its engines have failed?
A passenger aircraft will glide perfectly well even if all its engines have failed, it won’t simply fall out the sky. Infact it can fly for around 60 miles if it loses its engines at a typical cruise altitude of 36,000ft. Aircraft are designed in a way that allows them to glide through the air even with no engine thrust. The chances are that if you’ve flown on a plane, it will have been gliding during the descent when the engine is commanded by the pilots to produce very little thrust/power. For most of the descent, the engine is running at ‘idle’ (minimum thrust) – it maintains it’s forward airspeed by descending.
How Do Planes Keep Flying with no Engine Power?
Aircraft are able to fly because of the movement of air passing over the wings and as long as this process continues (i.e. the aeroplane is moving forwards at a suitable speed), the aircraft will continue to fly. If both engines fail, the aeroplane is no longer being pushed forwards through thrust, therefore in order to keep the air flowing over the wings, the aircraft must exchange energy through losing altitude (descending) in order to maintain forward airspeed. If the aircraft tried to maintain height with no thrust, it would stall (which would cause it to fall out the sky). However, pilots are trained for such occurances and will maintain a suitable air speed to keep the aeroplane flying.
The aircraft doesn’t have to lose altitude particularly rapidly to keep flying and therefore if both engines were to fail a high altitude, the aircraft may have as much as 20 – 30 minutes of airbourne time to find somewhere to land before it reaches the ground.
How far can a passenger jet glide if all its engines have failed?
A passenger jet could glide for up to about 60 miles if it suffers a total engine failure at its cruising altitude. Here’s an example. A typical commercial aircraft has a lift to drag ratio of around 10:1. This means that for every 10 miles it travels forward it loses 1 mile in altitude. If an aircraft is at a typical cruise altitude of 36,000 (which is 6 miles up) and loses both engines, it can therefore travel a forward distance of 60 miles before reaching the ground. Therefore, if such an incident occurs within 60 miles of a runway, the aircraft could potentially be landed safely.
US Airways Flight 1459
Rest assured, dual engine failure is almost unheard of. We all know about the story of US Airways flight 1459 landing in the Hudson River in New York after both its engines were destroyed by birds, but that really was exceptional – and everyone survived thanks to the quick actions of the actions of the pilots Captain Chesley Sullenberger (‘Sully’) and First Officer Jeffrey Skiles.
Air Transat Flight 236
One other exception was Air Transat Flight 236. The plane had a fuel leak causing both engines to fail at approximately 65 nautical miles from Lajes Air Base in the Azores. With an average descent rate of 2,000 fpm, the aircraft glided without power to the airbase where the crew carried out a successful landing about 17 minutes after the last engine failed.
Gliding Every Flight
The lower the engine power, the less fuel the engines burn. On most flights pilots try and burn as little fuel as possible and part of this process involves descending the aircraft towards the destination airport at idle (minimum) thrust. When the thrust is at it’s minimum setting, it isn’t really producing any meaningful thrust at all so the aircraft is effectively gliding. Therefore you will have experience the aircraft gliding on almost every flight you have been on!
If you found this article of interest, you may find our article about how both engines on a passenger jet can fail to be worth a read.