Nearly a decade ago, when he heard the details of the aeroplane accident that took John F Kennedy Jr's life, hedge fund manager David Gerstenhaber had an immediate sense of what might have gone wrong.

"There are many ways to regain control of an aircraft once you feel the least bit disoriented," he says, before running through a checklist of steps that could have been taken, involving an immediate shift to instrument readings over visual reckoning. His comments are more than mere speculation. Gerstenhaber is a certified twin-engine aircraft pilot, and he knows how to handle risk, in the air or on Wall Street. That has helped him turn in market-thumping results.