ICAO Wind

28.10.2004

Submission:

A question about Wind Spirals. I know two conditions: if we don t have wind data we use ICAO omni wind 30 kts (56 kph). If we have statistical wind data we use it (95% probability wind). But recently I have found another condition, the ICAO missed approach wind?

Vazgen Margaryan - Procedure Specialist - Russia

Answer or Commentary:

(I.W.

In ICAO there are quite a few winds (no pun intended )

-Omni directional 30 kts wind
This is used in approach and departure in the terminal area when creating the dreaded wind spirals

-Holding pattern wind
This is used in the construction of holding patterns at varying altitudes. The value increases with height and conforms to the formula 2h + 47 kts.

-Missed approach 10 kts wind
This wind is used in the calculation of "d" "X" and eventually the Start Of Climb. The wind is 10 kts as that is the amount of tailwind component that most aircraft can accept. The theory is that if the tailwind is more than 10kts ATC would change the runway.

-Visual circling 25 kts
The amount of wind used in the calculation of visual circling areas. Maybe some of the other procedure specialists know why this is 25 kts and not 30 kts or 47 kts?

Does anyone know the derivation of some of these winds?)