When to start engines?

[TKent 0]

In the normal airline world, is it allowed to start engines when still at the gate, or only after pushback? I don't want to suck stray people around the gate into the engines ... but when I take actual flights, it often seems like a very short time from pushback to taxi, not enough to start the engines only after pushback.

 

Tom Kent

[Stratox 22]

In real life you may ask ground to start one engine or multiple engines at the gate. Most of the time this is due to a mechanical issue where one engine is needed for a X bleed start. 99% of the time engines are started a moment after the aircraft is just about to enter the lane for taxi.

[A320FAN 370]

The procedure is done during pushback

[pete_auau 1,164]

during push back after getting the go ahead form the ground crew

[WR269 367]

It depends on a few factors.... I think the correct answer is : when you can!

 

A few airports will not allow engine start until you are on the taxiway.

 

Others require you to start one engine until in position ready to taxy.

 

Others will ask you start both on the stand due to proximity with the runway.

 

Normally it is done during pushback so by the time pushback is done you are ready to go into the taxi phase.

[Chock 17,769]

As others have already noted, it tends to be during pushback, which is why it is generally referred to as requesting 'push and start', but it is occasionally done at the gate, and it can depend on what the airport will allow.

 

It used to be fairly common to start engines at the gate, particularly with aircraft such as the 727 and DC-9 when things were busy and tugs were at a premium, or if it was icy and the pushback truck was slipping, since such aircraft were often able to reverse themselves out of the gate with one engine because the thrust was fairly central on such types, although the unecessary cost of fuel in doing so, the crap it blows up off the apron, possibility of FOD, and the noise involved is something which means that kind of thing is frowned upon these days, even with high bypass turbofans being generally quieter. Which means you'd certainly be less likely to be allowed to start the number 2 engine at the gate with something like an MD-11 or a DC-10, since its high position on the airframe makes the sound carry a lot further for one thing, which is one of several minor reasons why you don't tend to see tail mounted engines much these days, not that such types are very often at gates anyway nowadays.

 

Another reason they used to start things up at the gate more often years ago, was that when the aircraft was chocked, if it got a hot start and possibly an engine fire, which was a little more likely to happen before the kind of automated start systems you have these days were commonplace, especially with a tailwind, it would be a hell of a lot easier to do something about it when the aircraft was still stationary and near to suitable equipment instead in motion, including using extinguisers and disembarking the passengers if necessary, since there were rarely anywhere near the numbers of passengers you find on airliners these days.

 

If you watch old footage of airliners, particularly big propliners such as the Britannia, Stratocruiser and Constellation, you will often see a guy stood there on the apron with a fire extinguisher when they crank the engines, although how much one person could do with a fire extinguisher on a massive 24 cylinder engine with a 20 foot diameter propeller whizzing around if it caught fire, is of course debatable. But then again, it was quite often the case that such aeroplanes were not at a gate at all, with passengers usually walking out to the aircraft or getting driven there on a bus, so there wasn't always a pushback maneuver done anyway.

 

Al

[rocketfs 2]

Almost all the flights I've done, engines were started during pushback. Sometimes they waited untill pushback was completed. Maybe because the wind was windmilling the engines?

 

Bert Van Bulck

[vc10man 732]

Every pushback, be it 737, 767, AB, 747 that I have observed at my nearest airport, Manchester International, the engine starts have taken place after the pushback onto the taxiway, and the tug has released.

[kevinh 409]

As others have already noted, it tends to be during pushback, which is why it is generally referred to as requesting 'push and start', but it is occasionally done at the gate, and it can depend on what the airport will allow.

 

It used to be fairly common to start engines at the gate, particularly with aircraft such as the 727 and DC-9 when things were busy and tugs were at a premium, or if it was icy and the pushback truck was slipping, since such aircraft were often able to reverse themselves out of the gate with one engine because the thrust was fairly central on such types, although the unecessary cost of fuel in doing so, the crap it blows up off the apron, possibility of FOD, and the noise involved is something which means that kind of thing is frowned upon these days, even with high bypass turbofans being generally quieter. Which means you'd certainly be less likely to be allowed to start the number 2 engine at the gate with something like an MD-11 or a DC-10, since its high position on the airframe makes the sound carry a lot further for one thing, which is one of several minor reasons why you don't tend to see tail mounted engines much these days, not that such types are very often at gates anyway nowadays.

 

Another reason they used to start things up at the gate more often years ago, was that when the aircraft was chocked, if it got a hot start and possibly an engine fire, which was a little more likely to happen before the kind of automated start systems you have these days were commonplace, especially with a tailwind, it would be a hell of a lot easier to do something about it when the aircraft was still stationary and near to suitable equipment instead in motion, including using extinguisers and disembarking the passengers if necessary, since there were rarely anywhere near the numbers of passengers you find on airliners these days.

 

If you watch old footage of airliners, particularly big propliners such as the Britannia, Stratocruiser and Constellation, you will often see a guy stood there on the apron with a fire extinguisher when they crank the engines, although how much one person could do with a fire extinguisher on a massive 24 cylinder engine with a 20 foot diameter propeller whizzing around if it caught fire, is of course debatable. But then again, it was quite often the case that such aeroplanes were not at a gate at all, with passengers usually walking out to the aircraft or getting driven there on a bus, so there wasn't always a pushback maneuver done anyway.

 

Al

Al,

 

Apart from having fuselage mounted engines, powerback was possible on aircraft like the DC-9 and 727 because their engines had fully reversed airflow. Modern high bypass fans don't, the exhaust thrust still acts forwards. They don't produce enough reverse thrust at low speed to powerback unless very high power is used.

 

The elevation of engine 2 on the DC-10 is not a noise limitation at the gate as far as I know. Being a hundred yards away after a pushback won't make it any quieter either.

 

In the days of the big propliners there was no pushback. Aircraft were still usually parked at a gate, but turned side on with airstairs at the doors. Necessarily they started engines at the gate. As for the guy with the fire extinguisher, he's still there. A fire on the ramp is serious, whether it happens at the gate or at the end of a pushback.

[rocketfs 2]

Every pushback, be it 737, 767, AB, 747 that I have observed at my nearest airport, Manchester International, the engine starts have taken place after the pushback onto the taxiway, and the tug has released.

 

Must be coincidence. I see no restriction in their AIP and youtube shows engines starting up during the push.

 

 

Bert Van Bulck

[Airbus Commander 563]

One big reason for starting during or after the push is that, god forbid, an engine should erupt into flames during the start, you've been removed back from the terminal full of passengers, the fuel lines running around the terminal, the gate clutter that would restrict the access of the fire crews and it would also ensure there was enough space around the aircraft to deploy the slides. That's why at a lot of airports, you're only allowed start during or after the push unless restricted by tech reasons.

 

Capt. Rónán O Cadhain.

[Spin737 102]

Different airports have different procedures. Some want you pushed back past a certain line or spot before you start, others have no restrictions. If you are starting at the gate, it's normally because of an inoperable APU, and you'll be telling ground or ramp that you are doing so.

[scandinavian13 5,192]

The elevation of engine 2 on the DC-10 is not a noise limitation at the gate as far as I know. Being a hundred yards away after a pushback won't make it any quieter either.

 

Not true and you're not looking at the issue from the right angle. First, if you look at many of the major EU airports, you'll see specific limitations on the tail mounted engines for exactly the reason Al mentioned. Second, the issue isn't noise issues located on the airport, it's that the sound carries over the blast fences and trees and affects the surrounding area. Following that, it's not an issue of distance, it's an issue of time. If they start the number two engine later, there's less sound exposure (measured by time) between its start and when the plane is up, out, and no longer a factor.

[kevinh 409]

 

Not true and you're not looking at the issue from the right angle. First, if you look at many of the major EU airports, you'll see specific limitations on the tail mounted engines for exactly the reason Al mentioned. Second, the issue isn't noise issues located on the airport, it's that the sound carries over the blast fences and trees and affects the surrounding area. Following that, it's not an issue of distance, it's an issue of time. If they start the number two engine later, there's less sound exposure (measured by time) between its start and when the plane is up, out, and no longer a factor.

Accepted, but it is not a reason for the engine to be started after pushback rather than at the gate. It's more a reason to delay starting #2 for much longer. Also not all tail mounted engines are mounted as high as in the DC-10 and MD-11. Most have a centreline thrust line and therefore noise.

[dreyer 0]

My experince as a ground handler is that after we have started pushback we let them start the engines. But, if we need to use an air starter we let them start up normally engine 1 at stand, before pushing them out to the stop bar. And if its realy icy they have to wait until pushback is done before they can start up.