The method for producing a group III nitride semiconductor crystal of the invention comprises a step of preparing a seed crystal having a non-polar plane followed by growing a group III nitride semiconductor from the non-polar plane in a vapor phase, wherein the growing step includes growing the group III nitride semiconductor so as to extend in the +C-axis direction of the seed crystal. A catalyst and oxygen-containing Diesel fuel are also provided. In this embodiment, a spring is disposed in the second chamber and configured to apply a biasing force on a first piston disposed within the first chamber. When the operating state is determined to be abnormal, the alternate control node sets its own address into a control node address. A fifth subsystem packages the weather, airport configuration, aircraft state, desired landingtakeoff sequence, and potential conflict detection into a verbal advisory message that is broadcast on a local common radio frequency.