Cold weather and airliners
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Cold weather and airliners
Lately in the UK, (London area in particular), it has been very cold by my standards in the mornig. Its lovely to wake up to clear skies and aircraft contrails at 8am but I just wanted to know if you big guys and EGK and GLL do anything different to get the planes up and running.
Do your runway distances and fuel load get affected? Do you use more "voltage" due to anti ices being on all over the place? Do you have these on as soon as you sit in the pointy end?
What other factors must you concider with such climatic conditions?
Smooth skies
Dan
Do your runway distances and fuel load get affected? Do you use more "voltage" due to anti ices being on all over the place? Do you have these on as soon as you sit in the pointy end?
What other factors must you concider with such climatic conditions?
Smooth skies
Dan
Join Date: Feb 2000
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At the planning stage, if the runway is contaminated in any way by ice or snow, then the performance calculations, ie, V1 and Vr and max take-off weight are more complicated than usual. These calculations can become quite involved, especially if you're operating at high weights out of a fairly limiting field. This is due to the lower acceleration achieved in wet snow for example, and/or, worse braking in slippery conditions if we have to abort the take-off. Likewise for landing distance required if destination and alternates are affected. Max amount of fuel we can carry will thus be limited by this and number of passengers on board, plus their bags and any cargo.
If it's just cold but dry, then performance planning is normal. In fact, max take-off weight will be higher because of the colder temperature.
Once we get out to the aircraft, if there's any covering of frost then it must be de-iced. Sometimes this is already done by switched on engineers at main base. Other times, if night stopping somewhere then you may find yourself in for a long wait as the de-icing truck makes it's way round everybody. (Can happen at main bases too!) Only contaminant allowed on the airframe would be a very thin layer of frost on the fuselage (and I do mean thin).
Meanwhile you'll have started the APU to provide heat and power for the cabin. If this is not available (most turboprops for example, or it may be u/s on a jet), then you'll need external power, and if you're very lucky, an external air cart to pump warm air into the cabin. Not nice for the passengers (or the crew) getting onto a freezing aeroplane.
If the de-icing's been done at this stage, doing the walkround can be a pain as the fluid drips off the wings and fuselage and has a nasty habit of finding its way down the gap between your shirt collar and the back of your neck. Also makes the soles of your shoes very slippy.
In some places de-icing is done at a certain point on the field, and all aircraft taxy through here on there way to take-off. Can result in big delays.
Have to be careful that frost doesn't re-appear on wings. De-icing fluid has a "holdover" time which is tabulated depending on type of contaminant, air temp, type of fluid, temp of fluid and strength. So in falling snow for example, (where strictly speaking you've been "anti-iced" with stronger fluid), a long wait at the holding point could see you having to return to the gate to be de-iced again if you go over the holdover time.
In very cold temperatures, engine starting can be a problem. Oil pressures have to be monitored carefully amongst other things.
Generally engine and wing anti-ice will go on after engine start. There are various sops with regard to this dependent on aircraft type etc, too many to go into here.
In very cold weather with moisture present in the air, freezing fog for example, then an engine run-up to a high power setting would need to be done (again type specific), every half hour to clear any blade icing on a high-bypass jet engine for example.
Care has to be taken taxying the aircraft if there's any ice around. In snow, flap selection may be left until just before take-off, to prevent a build-up of slush in the flap tracks. This would then freeze after take-off, and stop the flaps retracting.
All this and we haven't even taken off yet! (Although apparently all we do is push buttons.
) Anyway, hope that answers your question.
If it's just cold but dry, then performance planning is normal. In fact, max take-off weight will be higher because of the colder temperature.
Once we get out to the aircraft, if there's any covering of frost then it must be de-iced. Sometimes this is already done by switched on engineers at main base. Other times, if night stopping somewhere then you may find yourself in for a long wait as the de-icing truck makes it's way round everybody. (Can happen at main bases too!) Only contaminant allowed on the airframe would be a very thin layer of frost on the fuselage (and I do mean thin).
Meanwhile you'll have started the APU to provide heat and power for the cabin. If this is not available (most turboprops for example, or it may be u/s on a jet), then you'll need external power, and if you're very lucky, an external air cart to pump warm air into the cabin. Not nice for the passengers (or the crew) getting onto a freezing aeroplane.
If the de-icing's been done at this stage, doing the walkround can be a pain as the fluid drips off the wings and fuselage and has a nasty habit of finding its way down the gap between your shirt collar and the back of your neck. Also makes the soles of your shoes very slippy.
In some places de-icing is done at a certain point on the field, and all aircraft taxy through here on there way to take-off. Can result in big delays.
Have to be careful that frost doesn't re-appear on wings. De-icing fluid has a "holdover" time which is tabulated depending on type of contaminant, air temp, type of fluid, temp of fluid and strength. So in falling snow for example, (where strictly speaking you've been "anti-iced" with stronger fluid), a long wait at the holding point could see you having to return to the gate to be de-iced again if you go over the holdover time.
In very cold temperatures, engine starting can be a problem. Oil pressures have to be monitored carefully amongst other things.
Generally engine and wing anti-ice will go on after engine start. There are various sops with regard to this dependent on aircraft type etc, too many to go into here.
In very cold weather with moisture present in the air, freezing fog for example, then an engine run-up to a high power setting would need to be done (again type specific), every half hour to clear any blade icing on a high-bypass jet engine for example.
Care has to be taken taxying the aircraft if there's any ice around. In snow, flap selection may be left until just before take-off, to prevent a build-up of slush in the flap tracks. This would then freeze after take-off, and stop the flaps retracting.
All this and we haven't even taken off yet! (Although apparently all we do is push buttons.
) Anyway, hope that answers your question.
