Runway Selection
 

Hey every1 i need help in understanding how runways are selected for take off and Landing. I know the basics of taking off into the wind but get confused with how to interpret the active runways from metar reports????? pls help

Many thanks

VIR001:ugh:

It can be confusing.
what you have to remember is:
on the reports WIND = Direction Coming from. So 230@7kts Is coming from 230 degrees as opposed to heading 230.
Runways are the opposite, and are the direction they are Facing. So RWY23 is approximatly heading 230 degrees.
Therefore, a Surface wind of 230 would mean that Runway 23 is in use ( for simple terms). Because the wind is coming from 230 and so you take off on runway 23 because its towards the wind facing 230.
hope this makes sence..
If it doesn't, i apologise, but i know what i mean :}
TC
Sam

yeah thanks it makes sense lol but what would be the case say if the winds where 310 at 5KT at EGLL?? Which runway then?? cos there is no RWY 31 @ EGLL

You just rotate the airfield until the runway is into wind! (sorry couldn't resist it)

yeah thanks it makes sense lol but what would be the case say if the winds where 310 at 5KT at EGLL??


Well in that case, you would use one of the 27's - The wind would be coming from slightly right of the runway, still more into wind than if using 09s. (Plus the strength would dictate 27's anyway as they are the preferred runways for the aerodrome in light wind conditions)

DF

In that case you have to take into account things like tailwind component(that is how much wind is "pushing" the aircraft).The 2000 foot wind is also a consideration.It can be significant for example when the surface wind is calm. Noise and local constraints apart the runway in the wind conditions described would be 27(although it is such a gentle breeze it might not really matter:)) The choice of runway has many factors to be taken into account and whilst the wind is certainly important it is not the only consideration.
Chevron...that only works with Navy pilots!!:cool:

LL or KK rules
 

Many years ago, there was a 5 knot tailwind component allowance for the preferential runway direction. Any updates from active controllers into this BAA inspired noise abatement process?

It's still the case at Heathrow. Westerlies are preferred up to a 5kt tailwind provided the runway is dry, and the crosswind component isn't more than 12kts.

Ahhh, now this sounds like a professional knowledge question:

Serviceability of airfield surfaces
Serviceability of instrument approach aids
Position of sun/moon
runway gradient

sorry bored now. Drinking and typing only gets me so far.....:ok:

The 5 kt tailwind component for preferential runway operation comes from ICAO Doc 8168 Part 5 Chapter 2 not BAA.

The fact that it's westerly preferential comes from BAA.

Still in use at Gatwick too, especially for Northern Runway ops....which we all LOVE :rolleyes:

Gonzo,

Why does BAA prefer Westerlies? Probably such a simple answer I'm missing it! :ugh:

Thanks

Doesn't the whole 'Preferential Westerly' thing stem from when the Airfield was first built, and general prevailing winds were taken into account?

Unfortunately there is really no way to discern the active runway from the metar report.
Which runway will be assigned for takeoff is one of the great mysteries of aviation.

Due to noise abatement over London.

I thought it was due to prevailing winds also but noise? Surely planes are going to make noise over London which ever runway they use? :confused: Do planes make more noise taking off or landing?

G-Nick, I think you are mixing up issues here.

To start from the beginning, there are many factors regarding runway selection.

The basic one is the current (and forecast) wind. Obviously the ideal is to operate into wind. If the wind is light and variable, one will usually take into account the forecast wind (runway end changes usually cause delays at busy airports, so by setting up early or during a quiet period of calm wind, delays can be minimised).

That's the main one. If the wind is below 5kts, then one can choose either end to operate off. In that situation, there are many other factors that come into play.....

-Serviceability of navigation aids (for example, only one end of the Instrument Landing System is serviceable).
-Serviceability of runway/approach lighting.
-Taxiway closures.
-And, where applicable, any airport authority edict that says one end should be preferred over the other, usually due to noise considerations.

In Heathrow's case, The westerly preferential system was devised when aircraft generated a great deal more noise than they do today on climb out, hence it was preferred to have the aircraft on approach over London, and climbing out over the more sparsely populated Windsor, Slough, Bracknell area.

Preferential procedures tell us which runway to use if there is no wind, all other factors being equal.

The prevailing wind is merely from which direction the wind is more likely to blow. In most of the south UK that is WSW, hence most airfields have a runway aligned from W to SW (Heathrow 27, Stansted 23, Gatwick 26 etc).

Thanks very much for the answer Gonzo, I feel like i've actually learnt something today :) :D

No problem, what was it and where did you............oh, you mean me! :}

Would you look at that, I've imparted knowledge.....first time for eveything I guess! :ok: