Eli5: Why can’t jetliners go backwards under their own power?
In: 2
on the ground or in the air?
If they were to back up from the jetway/terminal under their on power, they’d be spraying the terminal wall (usually mostly windows) with whatever debris kicked up by the jet engines. This could lead to damage and potentially injury if something goes through the glass and hits someone.
Do you mean on the ground or in the air? They can go backwards under their own power on the ground. It’s called a powerback.
They can using thrust reversal but most airports don’t allow it because it would blow away anything in the path of the air flow and it would increase noise and air pollution.
Because it would completely destroy the airport terminal if the jetliner backed out of the terminal under it’s own power. The engines aren’t even on while you’re at the terminal being pushed back. They only turn them on once you’re in a safe location where the jet wash won’t hurt anything. That’s why there’s a brief period between when you’re being pushed back from the terminal and you’re lined up on the taxiway where the air conditioning is shut off. While your at the terminal, air conditioning is provided by an air hose connected to the aircraft or an APU on the aircraft. They disconnect it once they start pushing you back; after the tow driver disconnects from the aircraft and the pilot is told it’s safe to start the engines the air conditioner will come online.
Secondly, it’s very difficult to back an airliner up, that’s why it involves a tow operator and 3 other people to make sure you’re not going to crash it into something. An airline pilot can only see what’s going on directly in front of them, not behind them. You can’t even see the wings from the cockpit.
They used to. It’s called a power back. It was very popular once upon a time but with increased focus on fuel economy and the bottom line of the airlines, tied into rising fuel costs, they fell out of favor. The last nail in the coffin was the focus on reducing the noise of the airport for surrounding populations. That’s why there are specific noise abatement procedures for arriving and departing traffic.
they can. here’s a (https://youtu.be/-Zkxh903s_w) of an md-80 backing itself out of a gate without “completely destroying the airport terminal” or “spraying the (all glass) terminal wall”
Turbine (jet engines) don’t run in change directions. Reverse thrust used to stop is performed by a V gate when landing. The V redirects the exhaust forward while the plane is going 100s mph. Like standing right in front of a fan. Why they don’t use it to back up, is because it uses to much fuel. And expells hot jet exhaust forward over the wing, that will damage the wing. Since the jet is not moving.
They should be able to since they have these things called bucket doors that when activated redirect the exhaust thrust forward(helps when landing). Why they choose not to may be for a bunch of practical reasons I’m unaware of.
Folks have already given pretty good answers (fuel use, noise, and FOD from ingesting bits being blown around) but there’s also one more downside.
If you get rolling backwards and you have to stop suddenly, your aircraft will try to do a tail stand. Now seeing a pilot pop a wheelie in a MD-80 might look cool, it’s gonna piss someone off.
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