Question about aircraft take off procedure
Discussion
AS a frequent flyer, I'm usually oblivious to take off and landing procedures. Yesterday however, I flew from Helsinki to Heathrow on a Finnair jet which had a camera in the landing gear which showed the view of take off.
I was watching it and the pilot spooled up the engines and took off down the runway as normal. He then took off and that's when I realised, there was still a hell of a lot of runway which he could have used, which got me thinking.
I know on landing, pilots often brake harder to take an earlier runway exit as the less an aircraft has to move around an airport, the better, however, on take off, the runway is of the sole use of the plane, which leads me to the question, on landing, the aircraft is directed by the control tower on which exit to use. On take off, does the control tower tell the captain to take off within certain parameters or is it up to the pilots discretion, once weather and weight are taken into account on whether to trundle down the runway for longer, or pull up into a sharper incline?
Hopefully that makes sense
Would be interested to know
Thx
I was watching it and the pilot spooled up the engines and took off down the runway as normal. He then took off and that's when I realised, there was still a hell of a lot of runway which he could have used, which got me thinking.
I know on landing, pilots often brake harder to take an earlier runway exit as the less an aircraft has to move around an airport, the better, however, on take off, the runway is of the sole use of the plane, which leads me to the question, on landing, the aircraft is directed by the control tower on which exit to use. On take off, does the control tower tell the captain to take off within certain parameters or is it up to the pilots discretion, once weather and weight are taken into account on whether to trundle down the runway for longer, or pull up into a sharper incline?
Hopefully that makes sense
Would be interested to knowThx
Fas1975 said:
On take off, does the control tower tell the captain to take off within certain parameters or is it up to the pilots discretion, once weather and weight are taken into account on whether to trundle down the runway for longer, or pull up into a sharper incline?
It's up to the pilots discretion where they lift off.http://www.youtube.com/watch?v=PLxEHIbHUlY
ATC might have something to say about how quickly they reach which altitude though.
Fas1975 said:
AS a frequent flyer, I'm usually oblivious to take off and landing procedures. Yesterday however, I flew from Helsinki to Heathrow on a Finnair jet which had a camera in the landing gear which showed the view of take off.
I was watching it and the pilot spooled up the engines and took off down the runway as normal. He then took off and that's when I realised, there was still a hell of a lot of runway which he could have used, which got me thinking.
I know on landing, pilots often brake harder to take an earlier runway exit as the less an aircraft has to move around an airport, the better, however, on take off, the runway is of the sole use of the plane, which leads me to the question, on landing, the aircraft is directed by the control tower on which exit to use. On take off, does the control tower tell the captain to take off within certain parameters or is it up to the pilots discretion, once weather and weight are taken into account on whether to trundle down the runway for longer, or pull up into a sharper incline?
Hopefully that makes sense Would be interested to know
Thx
Its down to the pilots to calculate the performance for that particular take off. There can be limitations on the usable length of the runway, work in progress or a runway entrance being used by another aircraft. Its all worked out by computer or using paper charts, using the wether conditions at the airport, the runway length available, the weight and CG of the aircraft, and any obstacles we have to clear in the climb out lane (trees, chimneys, ect). We usually use less than full thrust to save the engines. We will come up with various speeds to use during the takeoff roll and subsequent climb out. I was watching it and the pilot spooled up the engines and took off down the runway as normal. He then took off and that's when I realised, there was still a hell of a lot of runway which he could have used, which got me thinking.
I know on landing, pilots often brake harder to take an earlier runway exit as the less an aircraft has to move around an airport, the better, however, on take off, the runway is of the sole use of the plane, which leads me to the question, on landing, the aircraft is directed by the control tower on which exit to use. On take off, does the control tower tell the captain to take off within certain parameters or is it up to the pilots discretion, once weather and weight are taken into account on whether to trundle down the runway for longer, or pull up into a sharper incline?
Hopefully that makes sense
Would be interested to knowThx
VERY basically, aircraft take off when it reaches a set and calculated speed for each take off. It's not dictated by air traffic.
That speed varies with a multitude of factors like the runway length/slope and elevation, the hight of terrain around the airport, the weather, the aircraft weight etc.
Basically the aircraft take off speed is such that it before you take off you know when you have enough room to stop again if something goes wrong on the take off and can reach a certain height by the end of the RWY. So you calculate some different speeds for each take off so you know What speed you take off at, which speed you can still stop on the runway if you abort the take off and a Takeoff safety speed. Which is the speed at which the aircraft may safely become airborne with one engine inoperative. Those speeds obviously need to exist in a set order and some clearly have to be greater than others.
You also aim to save engine life by doing this at as reduced a power setting as possible.
That speed varies with a multitude of factors like the runway length/slope and elevation, the hight of terrain around the airport, the weather, the aircraft weight etc.
Basically the aircraft take off speed is such that it before you take off you know when you have enough room to stop again if something goes wrong on the take off and can reach a certain height by the end of the RWY. So you calculate some different speeds for each take off so you know What speed you take off at, which speed you can still stop on the runway if you abort the take off and a Takeoff safety speed. Which is the speed at which the aircraft may safely become airborne with one engine inoperative. Those speeds obviously need to exist in a set order and some clearly have to be greater than others.
You also aim to save engine life by doing this at as reduced a power setting as possible.
Dr Jekyll said:
It's up to the pilots discretion where they lift off.
http://www.youtube.com/watch?v=PLxEHIbHUlY
ATC might have something to say about how quickly they reach which altitude though.
Just watched this. Bloody hell!http://www.youtube.com/watch?v=PLxEHIbHUlY
ATC might have something to say about how quickly they reach which altitude though.
CaptainSlow said:
Follow up queston in regards to the doors. After landing you hear the "doors to manual" instruction. During flight is it possible to open one of the exit doors manually?
Doors are always opened manually, 'doors to manual' means that if the doors are opened the escape slide will have to be deployed manually if required instead of deploying automatically when the doors open.I believe it's possible in principle to open doors in flight at low altitude, but at cruising height the internal air pressure keeps them closed.
CaptainSlow said:
Follow up queston in regards to the doors. After landing you hear the "doors to manual" instruction. During flight is it possible to open one of the exit doors manually?
In theory, if there was no locking mechanism engaged, but it would be increasingly difficult as the aircraft gained altitude. The doors are designed to 'manoeuvre' into place and plug themselves against the inside of the door frame, so the greater the pressure inside the cabin relative to outside, the greater the force sealing the doors in place. Most airliner cabins are pressurised to the equivalent of the air pressure at 10,000ft, so it might be possible up to that height and maybe a little more.Dr Jekyll said:
CaptainSlow said:
Follow up queston in regards to the doors. After landing you hear the "doors to manual" instruction. During flight is it possible to open one of the exit doors manually?
Doors are always opened manually, 'doors to manual' means that if the doors are opened the escape slide will have to be deployed manually if required instead of deploying automatically when the doors open.
Hi,
On some Boeing aircraft they have a built in on board performance tool (OPT) which enables the pilots to calculate take off and landing performance.
You would first get the airfield weather conditions, namely the wind speed and direction, outside air temperature and the pressure setting in millibars or inches if flying in the USA.
You then select the airfield you are flying from or to and enter the current runway in use along with the weather conditions from above. From this you can then determine how much weight you can take off or land with. This will be you regulated take off or landing weight or if less than this the performance limited take off or landing weight.
You may on the day decide to depart from an intersection on the runway rather than use the full runway length. This option is line selectable from the OPT and then it will generate the performance figures. In basic terms it generates your flap setting, the engine out acceleration height, take off speeds and power setting. What it will do as mentioned previously is aim to take off using a reduced thrust setting which is geared towards preserving engine life due to the lower turbine temperatures generated.
Like any computer, garbage in garbage out, so it's imperative to have a robust method of determining the performance figures and thus ensure no mistakes can be made.
That's it in basic terms but you can add lots of other options as and when required.
With regards to the doors the flight locks engage during the take off roll and then once the aircraft has some differential pressure they will not be able to be opened in flight regardless. On occasion the aircraft flight locks may be unserviceable so with low diff pressures they may be opened during the initial climb at low level. I seem to recall the upper deck door on the 747-400 was not of the plug type and could be opened at low diff pressure. However it's been a while since worked on it so may be wrong.
On some Boeing aircraft they have a built in on board performance tool (OPT) which enables the pilots to calculate take off and landing performance.
You would first get the airfield weather conditions, namely the wind speed and direction, outside air temperature and the pressure setting in millibars or inches if flying in the USA.
You then select the airfield you are flying from or to and enter the current runway in use along with the weather conditions from above. From this you can then determine how much weight you can take off or land with. This will be you regulated take off or landing weight or if less than this the performance limited take off or landing weight.
You may on the day decide to depart from an intersection on the runway rather than use the full runway length. This option is line selectable from the OPT and then it will generate the performance figures. In basic terms it generates your flap setting, the engine out acceleration height, take off speeds and power setting. What it will do as mentioned previously is aim to take off using a reduced thrust setting which is geared towards preserving engine life due to the lower turbine temperatures generated.
Like any computer, garbage in garbage out, so it's imperative to have a robust method of determining the performance figures and thus ensure no mistakes can be made.
That's it in basic terms but you can add lots of other options as and when required.
With regards to the doors the flight locks engage during the take off roll and then once the aircraft has some differential pressure they will not be able to be opened in flight regardless. On occasion the aircraft flight locks may be unserviceable so with low diff pressures they may be opened during the initial climb at low level. I seem to recall the upper deck door on the 747-400 was not of the plug type and could be opened at low diff pressure. However it's been a while since worked on it so may be wrong.
Edited by khaosai on Thursday 18th April 11:45
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