If you're afraid of flying, it's one of the white-knuckled scenarios that pesters you every time you take off. You're flying along, peacefully looking down and admiring the urban design of Wichita, when all of a sudden the lights inside the cabin flicker and go dark. The engines go quiet, the plane starts to drift, and the silence is replaced by screams as you plunge toward a very hard landing in a not-so-cushy cornfield.
A full in-flight power outage means your ass, right? Actually, not even close. Power failure, though an extremely rare event on commercial jetliners, isn't anywhere near a catastrophic event. Modern airplanes are equipped with backup after backup of safety features to allow planes to land even after both engines and the electrical systems fail. Don't worry. The steps that follow your plane losing power are, yes, terrifying, but you'll likely land in one piece. Here's how.
If just the engines fail
Engine failure on airplanes is pretty rare. It's happened fewer than 10 times in the past 20 years -- most memorably in 2009 when an Airbus A320 belly-flopped into the Hudson River. That said, rarely do they include massive fatalities, since airplanes essentially become giant gliders once they lose engine power, and if pilots still have adequate electrical systems they can coast the plane down on the nearest airstrip (or field, or strip of frigid water). The average commercial airliner loses altitude at about a 15:1 ratio, meaning it can travel 15ft forward for every foot of altitude it drops. So an airplane flying at 32,000ft can go about 90 miles after engine failure.
If all the electrical systems fail
Engine failure does not necessarily mean electrical failure. Commercial planes are equipped with an auxiliary power unit, typically in the tail. This unit can be used to power the lights, pressurization system, and electrical controls of the plane if the power provided by the engines quits. And in the extremely unlikely event of a dual flameout, that juice can typically get the plane through until emergency landing.
And that's not the only backup system. Airliners are also equipped with something called a ram air turbine (RAT), inside the belly of the plane. When the plane senses engine failure, the turbine drops from the belly and creates power from the air passing under the plane, as a sort of onboard windmill. Believe it or not, this generates enough energy to run the plane's essential systems like navigation and fly-by-wire, in which the pilot puts commands into the computer system that can control the wings and rudders via hydraulics. You won't have cabin lights, and you may get cut off mid-Big Bang Theory episode, but you'll likely survive. This was how that Airbus that ditched in the Hudson was able to land with no fatalities.
If the plane is forced to run on this minimal power, it will also begin to lose cabin pressure, as that system isn't supported. As the plane descends, those oxygen masks you see in the safety demo will deploy, which have about 10 or 15 minutes' worth of oxygen for everyone on board. By the time that runs out, your plane will likely be below 15,000ft, and the masks won't be necessary.
If backup systems conk out
The plane is also equipped with battery systems, reserved for when all other systems fail. But since we're going down through worst-case scenarios, let's say those are also kaput. All is not lost! Though there is not a recorded instance of this in recent commercial aviation history, pilots train for this scenario in simulators all the time.
Commercial aircraft aren't designed to be gliders, but in an emergency they can be. In planes with hydraulics, pilots can control the rudder, stabilizer, and landing gear using only hydraulic systems. Even if one of these fails, most planes are equipped with multiple, redundant hydraulic systems (typically three) so that if one fails, the others can take over.
It's not so different in a plane with a fly-by-wire system. Those also have a mechanical backup that allows pilots to operate the plane if the power goes down
If all of those fail? You're officially on the unluckiest plane in history, and your landing is probably going to be a rough one. But it's also less likely than you hitting the Powerball. A commercial flight suffering total hydraulic failure caused by something other than an explosive has only happened three times since the 1970s.
The old-style 737 aircraft has a manual pulley system for rudder and aileron control, and can theoretically be controlled without hydraulic power. But you won't find many of those flying commercially in the United States.
So even if every power system on the plane fails -- a highly improbably occurrence -- your chances of survival are great. It might be terrifying, and might have you taking trains for the rest of your life, but it probably won't be fatal. The most likely case is you walk away with one hell of a story to tell.
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