Is anyone able to provide a reasonable explanation as to why the LL GPWT data format uses:
- 2 digits for wind direction, and
- 3 digits for wind speed?
All wind directions can be intuitively described with 3 digits, even if the leading digit is zero. I can generally grasp where a forecast wind of 030 or 090 is coming from.
But how often is a forecast low level wind in excess of 99 knots? The occasional cyclone involves low level winds in excess of 99 knots, but I generally don’t fly if the low level winds are forecast to be in excess of .... hmmmm.... I’ll pluck 75 knots. Makes things unpleasant, I guess.
Smart enough to remember that 9999 means in excess of 10KMs visibility. I reckon I have enough brain cells left to remember that a forecast wind of ‘99’ means in excess of 99 knots.
I note that all current LL GPWTs at the time of this post have a ‘0’ in the front of every forecast wind direction.
What awful and dangerous risks to aviation safety would arise if the LL GPWT format was:
- 3 digits for wind direction
- 2 digits for wind speed (with the rule that ‘99’ means in excess of 100 knots).
I realise my question assumes that someone’s reading LL GPWTs, and that that’s an heroic assumption. But humour me.
It might be the ICAO compliant format. I wonder where low level winds are routinely in excess of 99 knots...