wind calm

[alpergokgoz]

what is wind calm ?

[Sudden Stop]

No wind????

[Flybywyre]

That doesn't apply to me this morning :eek:

[eyeinthesky]

I seem to remember that you can only report 'Wind Calm' when the average wind displayed in the Tower shows 0 kts. Otherwise it is 'Less than 5 kts'. This is to allow the crew to decide which direction to turn the aircraft in the event of an engine fire on the runway. This is following the Manchester crash when the engine fire was spread over the fuselage by the wind.

[Defruiter]

In the UK, I believe you now have to pass exactly what the wind is, if it is below 5 knots.

i.e 1 knot
3 knots

etc...

I could be wrong though...

[JohnnyEagle]

I belive accoring to the ICAO annex it is less that 3 kts (2,1 or 0..), but I'll look it up at work later tonight :ok:

[jungping]

Accoring to the ICAO Doc4444, it is less than 1 knot.

[Short Approach?]

I tend to use it when the wind is 3 knots or less. Might have to think that over now with some of the inputs here. :confused:

[Tivoli Vertigo]

Accoring to the ICAO Doc4444, it is less than 1 knot.

There is 300+ pages, so can you tell me where exactly?

[JohnnyEagle]

ICAO Annex 3, appendix 3(?)and you'll find it. States less than 2km/h (1kt).

[2 sheds]

In the UK, "less than 5 knots" used to be passed because the old analogue anemometer dials (Monroe and similar) were not calibrated in one knot increments below a value of 5 knots as they were not accurate in that range. With the advent of digital instruments, they now read to the nearest one knot.

[judge11]

...and provide another opportunity to block valuable RT time. 'Westerly less than 5 knots' is fine.

[catocontrol]

In Norway, below 2kt

[fireflybob]

Interesting to note that in performance calculations that "calm" is not factored whereas head wind components are factored by 50% and tail wind components by 150%. So whilst it might seem like splitting hairs if you have planned on the wind being calm but the actual wind is three knots tail (say) and you are on max take off limit you would not strictly be in accordance with Performance A, etc.

Many years ago at the Luton Danair took some bits of the localiser aerial with them when they rotated for take off. One of the factors which created this incident was a light tailwind whereas the planning had assumed calm.