A: A 737 will descend to a lower altitude following the loss of an engine. This is known as driftdown. Pilots have charts telling them the driftdown altitude for the weight and temperature. This possibility is considered in flight planning to ensure that there is sufficient fuel on board to divert to an alternate airport and land with adequate reserves.
Q: What is the most accurate way to calculate the "halfway to Hawaii" time accounting for takeoff and landing speed variations from cruise speed?
— Michael, Conover, N.C.
A: The flight time is calculated based on the climb, en route and descent phases of flights. Computer flight plans estimate the wind, and provided and estimated ground speed. Based on those calculations, the 50% of the total time en route would provide a near halfway point on such a flight.
Q: If a plane should have to land in the ocean on a flight to Hawaii, would the pilots aim for the bottom or top of the ocean swell if there is one?
— Larry Steffen, Fraser, Colo.
A: The conventional training is to land parallel to the direction of the swells, midway up the face (trailing edge) of the swell.
In 1956, Pan Am Flight 6, a Boeing 377 Stratocruiser (Clipper Sovereign of the Skies), ditched in the Pacific Ocean near the USCGC Pontchartrain, an ocean-station ship midway between San Francisco and Honolulu.
The overspeeding of a propeller caused the loss of the #1 engine, subsequently the #4 engine failed too. With two engines out, the flight was unable to make California or to return to Hawaii.
They successfully ditched near the Coast Guard cutter, hitting a swell with the left wing first. All 31 people onboard survived. The airplane floated for 20 minutes then sank, killing 44 cases of live canaries.
John Cox is a retired airline captain with US Airways and runs his own aviation safety consulting company, Safety Operating Systems.