If a plane runs out of fuel will it just plummet to the ground or will it glide?

Question

In particular Im talking about 747's rather than light Cessna aircraft.

Answer 1

Every aircraft has a glide ratio. That is the number of forward motion feet for every foot in altitude loss in a glide. This is calculated at the best glide speed, a specific air speed in knots. If you maintain best glide speed you should achieve a descent rate at the optimal glide ratio. Lets say you are flying a small prop aircraft, a cessna 172 with a 9 to 1 glide ratio traveling at 8,500 feet at 120 knots and the engine quits.

1) The Pilot establishes a best glide rate speed of 68 Knots, loosing no altititude as he decelerates from 120 Knots to 68 knots trading airspped for keeping his alatitude at 8,500 feet. This would take a few minutes or so.

2) At the point that he stabalizes flight at best glide speed, 68 knots for a 172, much higher speed for a big jet, he begins to loose altitude at the rate of 1 foot for every nine feet traveled. 68 knots or about 82 mph.

3) He is traveling forard at 1.37 miles per minute. or 7,124 per minute. however for every nine feet traveled forward he looses a foot in altitude.

4) Therefore every minute he goes forward 7,124 feet but looses 792 feet in altitude.

5) 8,500 feet becomes zero feet in 10.7 minutes. He will hit the ground in 10.7 minutes, or thinking of this another way,he will fly in a straigth line at 82 mph for 14.6 miles befre hitting the ground.

6) He needs to avoid anything higher than his plane; buildings, mountains, bridges, towers, and eevntually trees and cows while searching for a safe place ot land in under ten minutes or less, hopefully much less.

7) Every plane glides this way at best glide speed. However, if you allow the plane to decelerate in speed to below glide speed the plane will stop flying and stall resulting in the plane rapidly falling towards the earth with decreased flight control and the risk of a spin. Stall speed increases with bank angle as well...factors..

8) A 747 works exactly like this in glide however the glide ratio. However, the glide ratio is 15:1. so for every foot 15 feet forward progress the 747 looses one foot of altitude...pretty good. And coupled with a high speed the glide idstance is quite high. Bad news is that a 747 is not well equipped for off road landings, too heavy, needs lots of space and runway so if you are in a glide you need to find a large airport with long runways, a gamble...hence four engines to provide redundancy and safety.

Answer 2

When fuel exhaustion occurs, the only option is to attempt to land at a suitable spot. All airplanes can glide if the engines stop, so it's a question of gliding down to a suitable landing place. As long as there is a spot that is smooth, flat, and at least moderately hard within gliding distance, a safe landing can be carried out. In practice, airliners will not stay in a holding pattern until they run out of fuel. The pilots know how much fuel they have and how long they can continue to fly. If fuel starts to run low, and they still cannot land at their original destination airport, they will divert to some other airport while they still have adequate fuel to reach other airports. There have been a few rare but famous cases of fuel exhaustion. In 1990, Avianca Flight 52 crashed after running out of fuel after spending a very long time in a holding pattern. The pilots never told ATC that they had serious fuel issues and never declared an emergency. By the time they attempted their first landing, they had only seconds of fuel remaining. They had to abort the landing because of the weather, but they had no fuel to go around, and the engines stopped as they attempted to go around, causing the aircraft to hit the ground. Just under half the people aboard were killed. You can google for this flight if you're interested in the details.

Answer 3

Each aircraft has a best glide speed which should be is known by the pilots who are qualified in that aircraft. That is the speed at which the aircraft will deliver the maximum amount of forward progress per foot of vertical descent or drop. . It varies for each type of aircraft. Fortunately, airliners have good glide ratios, if the crews have auxiliary power to control the flight surfaces. A 747
has a glide ratio of about 19/1 (19 units forward per unit of descent). from 35,000', an engine-out airliner can travel 100 miles or more. (Not that landing one is as easy as flying a glider; airliner's best glide speed is very fast and the vertical descent rate is also high.The space shuttle is only about 3/1., it drops like a rock.) Total failure of all engines is a very rare possibility. Even with such an occurrance, the pilots are well trained to handle the emergency.

Answer 4

All fixed wing aircraft can glide! The glide ratio may not be the best, but they all glide as long as the pilot does not stall the aircraft.

Yes B-747 and the larger A380 aircraft are capable of gliding for many, many miles in the event of losing all engines at cruise altitude.

Concorde, military aircraft and the Space Shuttle can also glide, though the glide ratio is very poor.

Helicopters, can auto-rotate, this is also like gliding.

Here is a list of glide ratios for various aircraft:

http://www.aerodyn.org/HighLift/ld-tables.html

Answer 5

If a plane runs out od fuel in mid air? LOL That is a easy one it just means that the plane does not have any fuel to land so it stays in the air.



but really in true fact, all planes can glide with out power for some distance to a field or clearing or if not that lucky pick a spot to crash and bail out if that is an option to before ditching the plane

Answer 6

Yes,

Planes can glide, but one of the issues of no fuel is that the aircraft will be on emergency power and many of the contols will be unavailable or offline.
There are two well known (Canadian) incidents of what is termed a fuel starvation incident where aircraft were landed safely after running out of fuel

http://aviation-safety.net/database/record.php?id=19830723-0
and
http://aviation-safety.net/database/record.php?id=20010824-1


Allthough they can glide they would have to make a much harder landing than usual and would have limited ability to adapt if conditions are poor.

Answer 7

The plane will glide. Each plane type has it's own glide characteristics. For example, a sail plane has no motor, but can fly for hours based on updrafts. Fighter jets have short wings for their weight and require massive amounts of power to stay in the air for any significant time.

Answer 8

It will glide for a certain period of time, but depending on size and weight as soon as it starts to lose speed it will start descending quicker and quicker until it literally just falls from the sky. When it crashes though, because there is no fuel, there is no fire..... See the link below to see the last time an accident like this occured. There was a suprising amount of survivors

http://www.pbs.org/wgbh/nova/planecrash/safer.html

Answer 9

It will glide. When you are in an airline and the pilots enter a descent from cruise altitude, they pull the throttles back to idle, At that point, you are gliding; just the same way that you would if you lost the engines altogether. Because the throttles are at idle, pilots glide when they descend every time they fly.

Answer 10

Its tendency would be to plummet. The skill of a pilot could use the momentum of the plummeting to gather enough speed for a "gentle" glide in the last few thousand feet til it crash lands. Chances are not good for all to survive though. Very likely there will be corpses involved.

Good news is that there won't be charred corpses, since the plane is out of fuel.