Question: If the engines quit at 30,000 feet, how far can a jetliner glide? -- submitted by reader Tonya Washington, Alexandria, Va. Answer: It would vary depending upon the wind, but around 100 miles would be a good estimate.
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The lift-drag ratio for commercial airliners is about 16:1. The distance that a 747 could glide is a function of altitude. Gliding from cruise altitude of 30,000 ft, or about five miles would have a range of 80 miles.
For example, with a glide ratio of 15:1, a Boeing 747-200 can glide for 150 kilometres (93 mi; 81 nmi) from a cruising altitude of 10,000 metres (33,000 ft).
Without engine thrust, a 747-200 has a glide ratio of roughly 15:1, meaning it can glide forward 15 kilometres for every kilometre it drops. The flight crew quickly determined that the aircraft was capable of gliding for 23 minutes and covering 91 nautical miles (169 km) from its flight level of 37,000 feet (11,000 m).
Flight 236 glided for nearly 75 miles. After gliding for nearly 75 miles or 121 kilometres, the plane touched down hard in Lajes, around 1,030 feet (310 m) past the runway threshold of runway 33, at a speed of around 200 knots at 06:45 UTC.
On August 24, 2001, an Air TransatAirbus A330 performed the longest-ever glide on a commercial aircraft before landing in the Azores. Without engine power, the aircraft glided for nearly 75 miles or 121 kilometres.
The first thing to bear in mind is that aeroplanes are not stones; they all have wings that allow them to glide in the event of engine failure. In fact, each aircraft has an associated glide ratio: an index that relates the metres an aircraft advances for every metre of altitude it loses in gliding.
One serving long-haul captain based in the UK explained to MailOnline Travel that 'typically a jet can glide about two miles for each 1,000ft of altitude'. He continued: 'So at 40,000ft cruise altitude the range of the aircraft to touchdown is about 80 miles.
The glide ratio of a clean A320 is 17:1 which means it can travel 17 units of distance forwards for every 1 unit of distance downward at best glide speed. Using your figure of 11,000 meters away and multiplying by 17 results in a maximum range of 187km .
Piche and his first officer, Dirk DeJager, with more than 20,000 hours of flight experience between them, proceeded to glide the Airbus A330, without any power, for 19 minutes - covering some 75 miles - until landing hard at Lajes Air Base.
Yes it will be able to glide just like any other jetliner. It's weight and size only factor into the distance of gliding, but it still acts as an airplane even when the engines are disengaged.
Flying at a typical altitude of 36,000 feet (about seven miles), an aircraft that loses both engines will be able to travel for another 70 miles before reaching the ground.
Techincally, there is only one way for the aircraft to remain hanging motionless in the air: if weight and lift cancel each other out perfectly, and at the same time thrust and drag cancel each other out too. But this is incredibly rare. To stay in the air and sustain its flight, an aircraft needs to be moving forward.
An A380 crosses the landing threshold at a docile 140 knots and touches down, depending on its landing weight, at a speed as slow as 130 knots, about the same touchdown speed of some corporate jets that weigh 1/50th as much as the world's biggest airliner.
Passenger jet pilots do not shut down any of the aircraft's engines without a solid reason. They may be forced to do so in the event of failure or even a relatively minor technical malfunction to avoid further damage and larger problems.