Wake turbulence separatin for HEAVY departures
Given the precision expected , I've often wondered why stop watches aren't mandatory at the air position. I certainly never saw them in use during my years in the uk
Join Date: Jun 2002
Location: UAE
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It's a minimum of 120 seconds (must be in a Nats AIC somewhere) and, yes, the controller estimates the time to roll and rotate but its not rocket science as depending on the type departing anywhere from 25-45 seconds works well.
As wake generation is only considered to start upon rotation thats the time that it's based on. It wouldn't really be the same if you waited two minutes from the commencement of roll due to the take-off runs required for different types/destinations. Eg. a B773 to South America will need a lot more Rwy than a B77f with a light load going to Europe. With the known rotation time you have one less variable to consider and it's easier to be more accurate.
As wake generation is only considered to start upon rotation thats the time that it's based on. It wouldn't really be the same if you waited two minutes from the commencement of roll due to the take-off runs required for different types/destinations. Eg. a B773 to South America will need a lot more Rwy than a B77f with a light load going to Europe. With the known rotation time you have one less variable to consider and it's easier to be more accurate.
@HD
Oh yes, I think most towers have always had that. However, using TR's scenario for example , when the B773 rotates you hit the start button on a stop-watch, all you have to do then is wait for the required interval & away goes the next. No need for mental arithmetic, fiddling the minute - is 30 seconds the minute before or after, that sort of thing. Just one less thing to occupy your attention & let you keep your eyes on the outside world, not your desk :-)
Oh yes, I think most towers have always had that. However, using TR's scenario for example , when the B773 rotates you hit the start button on a stop-watch, all you have to do then is wait for the required interval & away goes the next. No need for mental arithmetic, fiddling the minute - is 30 seconds the minute before or after, that sort of thing. Just one less thing to occupy your attention & let you keep your eyes on the outside world, not your desk :-)
Last edited by Eric T Cartman; 24th Jul 2016 at 09:33.
