On Jan 14, 11:05*am, Mxsmanic wrote:
Alan writes:
Several times for the past few years, while on a transatlantic flight
aboard a KLM 747-400, I begin to hear what sounds like a turbine
spinning up, almost like an engine start, but higher pitch...
Anyone know what it might be?

At what point in the flight? *And in which seat?

Do you have the seat schematics for different airlines?

-Robert