Wake turbulence avoidance and ATC

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.


All the best,


David