Working out the crosswind component
Joined: Jul 2005
Posts: 5
Likes: 0
From: Bournemouth
Here's one i don't think has been mentioned: i'm ready to be slated by the mathmeticians!!
For Crosswind component ..... Wind Angle + 20 in % = XWC
ie Rwy 26 Wind 300/30 (40+20) = 60% = 18kts
For Headwind Component ...... 110 - Wind Angle in %
ie Rwy 26 Wind 300/30 (110-40) = 70% = 21kts
Seems to work fairly accurately, I also like the clock method and of course the good old graph, especially when winds get a bit close to the limits!
For Crosswind component ..... Wind Angle + 20 in % = XWC
ie Rwy 26 Wind 300/30 (40+20) = 60% = 18kts
For Headwind Component ...... 110 - Wind Angle in %
ie Rwy 26 Wind 300/30 (110-40) = 70% = 21kts
Seems to work fairly accurately, I also like the clock method and of course the good old graph, especially when winds get a bit close to the limits!
Joined: Jan 2008
Posts: 465
Likes: 0
From: Finland
On approach, are you interested in the x-wind or the wind vector which gives you the maximum allowable/demonstrated x-wind for the runway in use?
When on Budgies in the Scottish Isles (and DC10 at bermuda), I used to write a wind table, for each ten degrees, giving this wind vector. That way I knew if I was within the limit.
It was sometimes useful to tell (ask) the controller to give no further wind checks after receiving one within limits.
A wind above the demonstrated limit was acceptable if everything felt right, whereas on other occasions I have gone around when the x-wind was within limits because turbulence made the aircraft almost uncontrollable.
A particular problem with a strong x-wind at 90 (or there about) degrees to the runway can be the along runway component.
Sumburgh 09/27 (15/33 not available at night) is a case in point.
A small change in wind direction can, with a strong northerly, cause the wind to come around the other side of Fitful Head giving an unexpected and sudden tailwind on landing despite the reported wind appearing to be a headwind
There is not much tarmac left if you land (three reds and a white and little or no flare - my technique at Sumburgh at night) with an 18kt tailwind on 09 !!
Cost me several beers to the firecrew in the helicopter club that night!!
When on Budgies in the Scottish Isles (and DC10 at bermuda), I used to write a wind table, for each ten degrees, giving this wind vector. That way I knew if I was within the limit.
It was sometimes useful to tell (ask) the controller to give no further wind checks after receiving one within limits.
A wind above the demonstrated limit was acceptable if everything felt right, whereas on other occasions I have gone around when the x-wind was within limits because turbulence made the aircraft almost uncontrollable.
A particular problem with a strong x-wind at 90 (or there about) degrees to the runway can be the along runway component.
Sumburgh 09/27 (15/33 not available at night) is a case in point.
A small change in wind direction can, with a strong northerly, cause the wind to come around the other side of Fitful Head giving an unexpected and sudden tailwind on landing despite the reported wind appearing to be a headwind
There is not much tarmac left if you land (three reds and a white and little or no flare - my technique at Sumburgh at night) with an 18kt tailwind on 09 !!
Cost me several beers to the firecrew in the helicopter club that night!!
Joined: Feb 2008
Posts: 33
Likes: 0
From: Chicago
You can find both the headwind or tailwind and the crosswind with this formula (a TI-83 calculator will do well with this):
sin(wind_direction-current_heading)*wind_speed = headwind or tailwind component
cos(wind_direction-current_heading)*wind_speed = crosswind
For headwinds and tailwinds, a negative number means a tailwind and naturally a positive number is a headwind.
For crosswinds, a negative number is from the left. A positive number means winds are from the right. Hope this helps!
sin(wind_direction-current_heading)*wind_speed = headwind or tailwind component
cos(wind_direction-current_heading)*wind_speed = crosswind
For headwinds and tailwinds, a negative number means a tailwind and naturally a positive number is a headwind.
For crosswinds, a negative number is from the left. A positive number means winds are from the right. Hope this helps!
