Jmarc99 wrote:
When you have 15 knots wind, with gusts at 20...

at 0 degree with the runway , you'll calculate 1.3 Vs + 15, right ?
at 45 degree ... calculate 1.3 Vs + 15, right.. maybe ?
at 90 degree ... calculate 1.3 Vs + 15, right.. no ?
at 135 degree ... calculate 1.3 Vs + 15, no.. right.. maybe ?
at 180 degree (wind right from the back) ... calculate 1.3 Vs + 15, always?

or 1.3 Vs + 20 knots at all times, whatever the wind direction with
the runway ? Or only 1.3 Vs when the wind will be at the back during
the final ?

The questtion is.. WHAT IS THE CALCULATED SPEED
do you wish to get during the base and final, according with
the wind angle with the runway. Do you take care the gusts speed
or not in your calculation ?

I can tell you what I'd do in England (that's important, because in very
different conditions, such as hot country or mountains, I'd be asking
local pilots for advice).

1. Nil wind landing speed for an airfield or flat field is 1.3 Vs. 10 kt
more for landing uphill, even more for a steep slope.

2. Plus half estimated max wind speed (i.e. gusts, not the average,
because you're giving yourself a margin for the worst that can happen).
So if the wind is 15kt gusting 20kt I'd add 10kt. Adding all the wind
speed is too much for a field landing, giving you a closer view of the
far hedge than is comfortable. I don't have different landing speeds for
runways and fields because it would be too easy to use the wrong one
under pressure.

3. If the wind is cross, there's a useful rule of thumb to reduce it by
1/6 for every 10 degrees from 90 to get the headwind component. 90
degrees cross = 0/6 (i.e. no head wind), 60 degrees cross=3/6 (half head
wind), 30 degrees cross=6/6 (full head wind). So in our example, if the
wind is 15/20kt at 60 degrees I'll treat it as gusting 10kt headwind and
add 5 kt.

4. Finally, you may need to add a margin for expected wind shear,
curlover etc - here you need advice from local pilots. If you've got
yourself into the situation where you only have a bad field you will
need to compromise, in which case remember that undershooting at flying
speed is usually worse than running into the far hedge at a lower speed.

Where I fly the fields are big and there are few hills, so input from
those who fly in more challenging areas would be worth reading.