Wake turbulence avoidance and ATC

David Megginson wrote:
David Rind wrote:

Not answering your actual question about the clearance, but for
what it's worth, I would not have tried to climb out at Vx. You
have no hope of outclimbing a jet,


It's not that far off -- I think (but am not certain) that a
fully-loaded DC-9 has a best climb angle of around 650 ft/nm, while a
small single-engine plane will manage something like 400-600 ft/nm at Vx
depending on horsepower and load. Of course, the DC-9 has a much better
climb *rate*, but that's not the concern here (also, the DC-9 is
designed for short fields; other transport jets may have worse climb
angles).

More importantly, a Vx climb will probably put you a couple of hundred
feet up and another 30 seconds behind by the time you arrive above the
point where the DC-9 lifted off -- that gives you lots of room to make a
turn before you intersect its path. If you took off at a higher speed,
you'd have less space for your turn because your climb angle would be
lower (even though the rate was higher). Even if you stay straight
ahead, at VX you probably won't intersect the DC-9's climb path until
the vortices are well-dissipated. A slow forward speed is your friend
in this situation, either way.

You are clearly right about this -- I was thinking in terms
of rate of climb, not angle of climb. That said, I would
still be more interested in making an early turn than in trying
to climb quickly and would always ask for an early turnout
in this situation....

--
David Rind