How Far Can a Plane Glide if Its Engines Fail?

By: Mark Mancini  | 

miracle on the Hudson
Rescue boats float next to U.S. Airways Flight 1549 floating in the water after it Capt. "Sully" Sullenberger safely landed it on the Hudson River Jan. 15, 2009, shortly after takeoff from LaGuardia Airport. Miraculously nobody was seriously injured. Jerritt Clark/Getty Images

It's Jan. 15, 2009. U.S. Airways Flight 1549 is being boarded at New York City's La Guardia Airport. If all goes as planned, the plane will touch down in Charlotte, North Carolina, later that evening.

All does not go as planned.

At 3:24 p.m., Eastern Standard Time, the aircraft — now laden with 150 passengers and five crewmembers — takes off. Within minutes, disaster strikes. The plane is unexpectedly bombarded by a flock of Canada geese, causing both engines to shut down at 2,800 feet (853 meters) above one of the world's biggest cities.

Sans engines, the airliner loses almost all of its thrust. This is a serious problem because thrust is the physical force that moves flying planes (and birds) in the direction of motion.

Unable to restart the engines, Capt. Chesley "Sully" Sullenberger and first officer Jeffrey Skiles have to act fast. Time is running short, and they're losing altitude.

If you watched any news on that winter's day in '09, then you probably know what happened next.

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Miracle on the Hudson

After considering detours to La Guardia and the Teterboro Airport in New Jersey, Sullenberger and Skiles pulled off an emergency landing on the frigid Hudson River. Although some passengers had serious injuries, everyone aboard that plane lived to tell the tale. New York Governor David Paterson called it a "Miracle on the Hudson."

The landing was both dramatic and unusual. But this wasn't the first time passing birds made trouble for a large aircraft. When gulls or geese get sucked into a plane's engine(s), they can do serious damage to the machinery. These "bird strikes" are the most common cause of dual engine failure on two-engine airplanes (like the one Sullenberger was flying).

However, if all of a plane's engines stop working in the middle of a flight, it might have nothing to do with our feathered friends. Maybe there's ice forming in the carburetor — an issue that caused 212 aerial accidents between 1998 and 2007, according to the Federal Aviation Administration (FAA).

Or perhaps the vehicle just doesn't have enough fuel. In 1983, a perfect storm of technical issues and unit conversion mistakes left an Air Canada Boeing 767 without fuel some 41,000 feet (12,496 meters) over central Canada. Before long, it lost power to both engines.

After descending at a rate of 2,500 feet (762 meters) per minute, pilots Bob Pearson and Maurice Quintal were able to glide their Boeing all the way to a safe, albeit bumpy, landing on a Manitoba race car track. The pilots were hailed heroes and the airplane was dubbed the Gimli Glider after the town where it landed.

Gimli Glider
Pilots Bob Pearson and Maurice Quintal were hailed heroes after they glided their Boeing 767 safely from 41,000 to land on a Manitoba race car track in Gimli, Manitoba. The airplane was dubbed the Gimli Glider from then on.
Wikipedia/(CC BY 4.0)

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How Far Can a Jetliner Glide?

So essentially, any plane can glide if the need arises. And in situations where all the engines have failed, pilots have to expect the plane to do some gliding. Without the thrust those engines are built to provide, the plane can't help but lose altitude. But how far can a plane glide when it's not designed to be a glider?

Aircrafts whose engines conk out at higher elevations can glide for longer periods of time. This is one of the reasons why Sullenberger and Skiles' Hudson River landing was so impressive; they had to glide their way to safety in a manner of minutes from a pretty low altitude. (Everything happened very fast on U.S. Airways Flight 4951. The plane hit the birds within two minutes of taking off and just three later, the plane was in the Hudson River.)

Obviously, planes come in all shapes and sizes. So if you're flying one, it's important to know your vehicle's "best glide speed." In a nutshell, this is the speed that will let your airplane travel the farthest distance while sacrificing the least amount of altitude.

A related concept is the minimum sink speed, the pace of travel that'll maximize how much time you can spend gliding. Depending on your situation, you may choose to prioritize time over distance or vice versa.

Writing for USA Today in 2013, veteran pilot John Cox stated that a jetliner could probably be expected to glide for around 100 miles (161 kilometers) if all its engines failed 30,000 feet (9,144 meters) above ground level. That's about the distance between Los Angeles and Palm Springs or New York City and Atlantic City. In other words, not very far.

"Having all engines quit in a modern airplane is extremely rare," Cox also noted. That's reassuring.

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