RTC – MOD-08 – Pt.02 – Wind
The wind is likely going to be the most affecting factor of the weather, it will dictate what runways you can use, what direction the carrier will attempt to sail, what offsets you apply to your weapon systems for AG delivery. It will even affect aircraft range significantly, so is an important part of planning.
Wind will be described in 2 or sometimes 3 parts;
Part 1 is a 3 figure direction in where the wind is coming FROM so 270 will mean the wind is coming FROM the west TO the east. As you take off INTO wind you will attempt to take off on the runway with a direction closest to 270 Deg. Wind direction is always to the nearest 10 Degrees.
Direction is always 3 figures, so 90 deg, will be given as 090. If the direction varies more than 10°, it’s given as “variable”.
Example: “Surface wind 010°; 9kt; variable between 350° and 050°”
The Part 2 component given is speed. For our purposes, it will always be in knots (unit: kt). If you come across the speed component in m/s or meters per second, doubling it will give a reliable conversion to knots.
In radio comms, there is no digit requirement for the speed component, so 9 knots will be given as 9, not 09 or 009 knots.
Wind speeds of less than 5 knots will be passed as calm.
The Part 3 component of wind is the gust component. When written it will be G# where # is the speed of the gusts, or spoken as gusting #.
Gusts will only be given when the Gust is 5kt or more than the average wind speed.
“Wind 050, 15, gusting 25kt”
This means the wind is coming FROM 050 Deg, at 15kt, with gusts of up to 25kt in the last 5 minutes.
It is also important to know that wind slows down and changes direction the closer to surface level it is, so winds higher up in the atmosphere (known as winds aloft) will be significantly stronger as there are fewer obstacles in its path to slow and change it.
The way to remember this is to say the wind backs and slacks as it gets closer to the surface. Meaning the direction goes backward (Counter/Anticlockwise) around the compass and slacks, as in eases off.
So a wind of 090° 70kt at FL250 will be much more like 010° 10kt at surface level.
Wind is an essential element in the planning cycle. Headwinds into the target area will reduce your Ground Speed (GS) and mean you burn more fuel into the AO, you may need to plan the AAR on ingress. Conversely if you have a tail wind into the AO, you may have much more fuel on ingress, but will need to be more mindful on egress and may need to AAR at this point in the mission.
For crosswind components to transit, you will need to do some maths! But that is beyond the scope of this module.