Separation by tower

David Cartwright wrote:




My local airport can get busy at times (reasonable amounts of GA, and we
share the airfield with everything up to 767s) but we don't get a lot of
"chasing down the runway". I've had a few "land after"s, but we've got
1,850m of runway and they're no problem (and anyway, it's only an invitation
that one can decline, not an order).

Also remember that as soon as the plane flies off the end of the runway
the separation standard disapperars. So what was once 3000 feet goes to
zero.



I've not had a take-off clearance when they guy in front still had his
wheels on the runway,

Go to any big city airport. You will see jets touching down as the jet
taking off still has his mains on the runway. You will see jets getting
a takeoff clearance as the preceding jet departure is about 5000 feet
down the runway and just starting to come up off the nosewheel.


but I _have_ had plenty when he was only a hundred or
two feet in the air. And the clearance was always of the form: "Departing
traffic is a C152 [or whatever] turning left on departure; with that traffic
in sight, cleared for take-off ...".

He doesn't need to say all that, that's probably why the other guy is
already 200 feet in the air, he's wasting air time. But that happens
everywhere. We have a couple guys here that when they want you to start
a turn early will actually say "when speed and altitude permit start
your crosswind." I just sit there and laugh.




I suspect the main thing the controller
needs to be thinking is not so much the formal separation distance, but the
consequences of two single-engine aircraft suffering an EFATO and having to
set down - the last thing you need is a runway with one small "obvious"
EFATO field at the end of it and two aircraft both heading for it at once!

A plane has an engine failure is an emergency situation and the rules
don't apply if we then have two on the runway. Been there, done that.


Only if you have lined up
under a "line up if able to commence immediate departure" do you have any
compulsion to get your skates on!

Man, that's cumbersome.