Peter R. wrote:
My point of climbing at Vx was not to outclimb the DC9, which rotated about
7,000 feet down the runway. My point was to get above the obstacle DP
altitude well before the DC9s rotation point, then turn the 90 degrees
right that the tower had already approved.

Were you in IMC such that the DP altitude mattered to you?
I was picturing this happening in visual conditions where you
could start maneuvering (as long as Logan permitted) much
sooner.

--
David Rind