Why can't airplanes reverse out of the terminal on their own?

Question

You always notice that they have to be pushed out by another moving vehicle? Why?

Answer 1

simply because they have no reverse gear,  thats it.

Answer 2

Most of them technically COULD do it, but anyone in front of the aircraft (including those inside the terminal) wouldn't be too happy about it.

Answer 3

Jets can't.  Some turbo-props can.

It's pretty cool to watch.

Do remember though, that you can't see behind you from the cockpit, so it's not done often.

Answer 4

Most aircraft don't have sufficient power in "reverse thrust" to move the aircraft. You would also need to have personnel to instruct the pilot if it is safe and they would be in the jet blast area (highly unsafe). It would also be blowing toward the Jetway area. It is just a lot easier and safer to back it out with a tug.

Answer 5

1. Not all aircraft are fitted with thrust reversers.

2. It uses a lot of fuel to use reverse thrust.

3. A tug doesn't stir up every loose piece ot trash near the terminal.

For all the people who answered not enough power, you are wrong. One airline, I can't remember which routinely used reverse thrust to back out of the space.  As far as seeing where you are backing, the the nosewheel stripe is used as a guide. The tiller steers the nosewheel, so one engine can be used after the craft untracks.

Answer 6

Because thrust reversers wastes fuel, can possibly draw contaminants into the engine, such as dirt snow.

It's also quite dangerous because of all the ground crew and equipment assembled near the terminal.

Answer 7

Most of the above answers are correct.

The only exception I know of is the Lockheed C.130 Hercules. Even then it is only used when there is no alternative, due to the risk of damage to the aircraft by the debris thrown up.

Ian M

Answer 8

because they have to be guided out, and standing in front of 2 or 4 engines with thrust reversers engaged would be challenging to say the least, and for safety reasons if an engine should fail the ground crew and fuel trucks would be safe.

Answer 9

The reason that an airplane can't reverse out of the terminal is because it has no gears. Planes only have reverse throttle which helps slow the plane down when it lands. The reason that they use another vehicle to move jets back is that the reverse thrusters don't have enough power to move the plane back.

Answer 10

jet engines don't have a reserve gear (or any other gear, technically). they do have thrust reversers, but those are designed to be used for braking on landing, not moving an aircraft. besides, it more economical to use a tug than to burn that much extra jet fuel

Answer 11

Lots of interesting theories here, and some contributions by people who know what they are writing about.

Many types of jet airliners are equipped with thrust reversers, though certainly not all are.  As a general rule, jet airliners with the engines mounted on/in the tail cone can be powered back (backed up using the thrust reversers) with reasonable ease and safety, though lookouts are required all around the airplane to make sure the airplane stays out of the way of other aircraft and doesn't back into or over something.

Back in the days when Boeing 727s were in major airline service, "powering back" was not an uncommon sight.  There are still some hazards involved, as you stir up a lot of trash and junk, and you can damage the landing gear and some airframe parts by turning too sharply.

Airplanes with jet engines mounted under the wings cannot be powered back.  Or at least they should not ever be.  It is done, rarely, but it is dangerous and can be damaging.  Most companies forbid it.

Airplanes, either turbine or piston, that have reversible propellers can be backed under power much more easily and safely.  The C-130 is a good example.  Because it is a high-wing airplane, the propellers don't stir up near as much trash as they would in the same maneuver with a low-wing airplane.

We used to back our piston engine Convairs and Douglases all the time.  It isn't too hazardous if the ramp is kept clean.  I once backed a DC-6 into a hangar with about nine lookouts.  I had less than eight feet clearance on each wingtip, and, of course I could not see where the bejezus I was going.  So I trusted the guys on the ground, and we backed the airplane almost 300 feet without hurting anything.

I would not want to have tried the same thing with the 747s I later flew.  And of course you don't run jet engines in hangars, for obvious reasons.

There is another way to back an airplane.  Almost any multi-engine airplane can move backward by "wanking."  You set the brakes on one side and power up the engine on the same side.  That swings the airplane around, putting the opposite main wheels further back.  Repeat the process on the other side, and so on.  It's hard on the airplane, and, again, you can't see where you are going.  But it can be done in a pinch.

Answer 12

They can and do.

Answer 13

Thrust reversers are not designed to move a static aircraft backward. What they do is convert momentum from the huge amounts of air being sucked into the inlet into a load acting aft on the engine mounts. This is of course more efficient when the aircraft is moving forward at high speed, resulting in inlet ram air. Can it be done? Yes. But that is not what they were designed to do, and every time you run the engines up, you burn up another fatigue cycle on the turbines, which are life-limited based on a duty cycle that does not include such an operation.

Answer 14

They can, and will occasionlly do,  but it is an issue of safety.

Around the terminals, there is a lot of actiivty, such as people, carts, tugs, and other hazards.

The thrust necessary to push and aircraft back creates alot of jet/prop wash that can cause damage and injury to people and property around the terminal.

In addition, major airports are a busy place, and a push back with a tug makes sure that the aircraft doesnt run into anything while backing up.

Another big issue is FOD damage. The jet wash from a revere thrust will stir up debries found around the terminal that can get sucked into the engine and cause damage.

Another issue that can happen is a compressor stall, because of the turbulent or disrupted airflow to the engine intake - e.g. Use of reverse thrust at low forward speed, resulting in re-ingestion of hot turbulent air

Answer 15

DC-9s, C-130s, and Dash-8s back up no problem.  So do PT-6 powered planes like the Twin Otter and King Air.

Answer 16

Most commercial jet airplanes can reverse out of the terminal by use of the thrust reverser. Northwest airlines actually does use thrust reversers to back out of the gate on a regular basis with their DC9's. Although most can do this they usually dont because of the added fuel expense and the possibility of ingesting debris into the engine.

Answer 17

The TR's could be used to back out, but it is very wasteful and they can't see where they are going. I'm sure I'll get some thumbs down, and I'm not saying it's normal, but the TR's will move the aircraft backwards. I've seen pilots back up loaded C141s, but they have a ramp they can open so the loadmaster can see out.

The tug driver can see if anything is in the path of the moving aircraft, and he watches the wing walkers as well. Besides, they don't start engines until they get pushed away from the gate and there is a good clear area to light them off.

ADDED: Sorry Ian, the C130 uses reverse prop quite a bit to back up. That's normal ops on a quick offload. Some of the C130s at Ramstein Germany pull into a parking spot and must  back out when they leave; again, normal ops.