An airplane has a mass of 3.19 × 104 kg and takes off under the influence of a constant net force of 1.56 × 104 N. What is the net force that acts on the plane's 82.1-kg pilot?

Answer 1

well, something important is missing. Is this "net force" the accelerating force, I assume so. But the plane, and pilot also are under the influence of gravity, which is downward, and the accelerating force is almost perpendicular to gravity.

So ignoring gravity, and pilots weight...
accelerlation=massapirplane/netforce

then force on pilot,neglecting weight, is acceleration*82.1