Pierre Argh
30th Jan 2006, 15:12
Perhaps not what you thnk???
Almost 30 years in the ATC game... learnt this one this morning, Nocturnal Jets... never heard of it before?
Big a/c inbound, surface wind calm... quiet, so pilot elects to approach nearest runway but has to break off approach on short finals due to 20kts of tailwind at 200ftAAL???
Met man explains concept: How overnight shallow, but marked, inversion can form over cooling land (typically on long clear Winter nights). Geostrophic wind above inversion layer blows unabated by surface friction causing massive differential in surface wind and wind just above surface (above the Nocturnal Boundary Layer to be precise)...
Figures:
OAT (surf): -4deg SW: Calm
OAT(1000ft): +11deg SW Easterly 35kts
Pilots probably learnt all about that (one way or another)... amazing how much stuff isn't covered in ATC training... or maybe I was asleep at the time?
Almost 30 years in the ATC game... learnt this one this morning, Nocturnal Jets... never heard of it before?
Big a/c inbound, surface wind calm... quiet, so pilot elects to approach nearest runway but has to break off approach on short finals due to 20kts of tailwind at 200ftAAL???
Met man explains concept: How overnight shallow, but marked, inversion can form over cooling land (typically on long clear Winter nights). Geostrophic wind above inversion layer blows unabated by surface friction causing massive differential in surface wind and wind just above surface (above the Nocturnal Boundary Layer to be precise)...
Figures:
OAT (surf): -4deg SW: Calm
OAT(1000ft): +11deg SW Easterly 35kts
Pilots probably learnt all about that (one way or another)... amazing how much stuff isn't covered in ATC training... or maybe I was asleep at the time?