Question on pushbacks.
 

Hi, I have always wondered what actually happens during a pushback and why?

I gather when the aircraft is ready to go, it releases the breaks, the push-truck attaches its self to the front wheel then pushes back.

Why do pilots not just reverse thrust seeing as its such a short distance (can reverse thrust actually make the aircraft reverse in first place?) also id imagine that the noise levels would be a factor too.

just wondered , thanks

--tibbz

We can't see behind us.

At one time it was not unusual to see aircraft "powering Back" in the U.S. Experienced it myself with Delta and Eastern a few times - all in B727s.

mjtibbs

if you search for 'powerback' there are quite a few threads on the subject. :ok:

mjtibbs,

Eastern airways often use 'powerback' with their Jetstreams, though usually at the smaller, and less busy airports such as Southampton, Aberdeen and the Isle of Man. They use the reverse pitch of the props and yes, it is VERY noisy!! They must still have a ground crew to marshal them rearwards to ensure all is clear behind.

The pushback is team at a large airport such as Manchester often comprises of three ground crew. One to drive the Tug, one to interact with the flight crew (usually via a headset & intercom which plug into the side of the aircraft), and one to ensure that the passing airside 'road' traffic (catering vans, fuel trucks, baggage trucks etc) stops to allow the aircraft to be pushed away from it's stand and onto the taxiway.

Once the aircraft is ready to go (with it's doors closed), the tug is connected to the nose wheel with a 'tow bar' and i'ts park brake is set. The ground crew do a final walk-round to remove the wheel chocks, check all doors and hatches are closed and give the aircraft a final once-over! They will also usually unplug the Ground power unit if no longer required.

The flight crew usually request 'start and push' from the ground frequency of the airport. They will also ask the ground crew (via the intercom) if all their external checks are complete. Once everyone is happy, the 'red beacon' is swithed on from the flight deck (to alert everyone around that it is 'live'), and the flight crew will report 'cleared for push and start' and the ground crew will ask for 'brakes release', and start their pushback.

Whilst the push is underway, the flight crew will ask the headset guy (who walks out along-side the plane), if it is clear to start the engines one at a time, and if all clear behind, he will state clear and monitor the engine start from the outside (obviously informing the crew if anything unusual occurs)!!

Once the aircraft has been pushed into position on the taxiway, the ground crew will ask for the aircraft brakes to be set, the crew will confirm 'brakes set & engines running', and instruct the ground crew to disconnect. The 'tow bar' is detached from the nose wheel, the tug is driven clear and the headset guy unplugs from the aircraft and walks clear before facing the flight crew and giving a 'thumbs up' to indicate all ground equipment has been removed.

The flight crew signal back (with suitable hand gesture:ok: ) and the flight crew radio for 'taxi' Once cleared by ATC, of they go under their own steam!!

Hope that helps;)

W-S

Reverse thrust on high-bypass ratio underslung jet engines (ie most modern airliners) is not a good idea due to the high risk of FOD ingestion and engine damage.

Reversers are usually required to be at idle thrust by about 60-80kts forward speed - ay high thrust levels the amount of air scooped up by the intake is huge, and if stationary on stand would probably pick up all the baggage labels, gravel and loose nuts and bolts within a sizeable radius.

Not such a problem for aircraft with fuselage-mounted jet engines or props, as described above.

Another reason is that a/c would be sucking in the debris on a powered push back and I would suggest that it might be considered very unsafe at most airports. As someone said a pilot cannot see behind him, yet. I believe that a number of A340/330 do have this facility. Boeing is at present developing a 767 that has electric motorised nose wheels, thus the a/c will drive itself out and may be able to taxy for some length reducing amount of fuel used and perhaps saving a lot of noise adjacent to the terminal buildings.

mjtibbs - type 'powerback' into our search engine and you will find loads about it.

thanks for all the info guys :E

I should have thought about the search option :ugh:

You have cleared up my questions tho :ok:

cheers

--tibbz

Tangled tailfeathers
At ATL about 1985, two Eastern DC-9's backed into each other from opposing gates.

Pushback
 

In addition to not being able to see behind you, if your using reverse thrust to pushback on one of these birds, you could possibly tip the tail if you apply the brakes too hard...

Regards,
noullet

I should have clarified my post and inserted \'Pushback\' on a Boeing 727 a/c...

Sorry if I unintentionally misled anyone here.

Regards again,
noullet

Once witnessed a Falcon 90 'powerback' off Stand 6 at Southampton, several years ago now... this is the stand that faces the front face of the terminal building and to say it shook the windows would be an understatement...!