I agree with Byrd, I wouldn't want to be plugged into the plane's power systems when the APU or engines are coming on or off. The aircraft wiring harnesses are far more robust than your power cord and adapter, which makes your power cord the likely failure point in a big change situation.

If you are really concerned about fluctuations, the iGo power cords have a pretty sturdy set of electronical innards, suitable for aircraft variations as well as brown-out and return conditions. They aren't a surge protector, but they are probably better than your standard cord.