Abstract: A method for monitoring a gearbox in an aircraft. The gearbox comprises at least one gearbox section with at least one measuring area. A first and a second electrical contact are arranged in the measuring area at a spacing from one another. A magnetic field is generated in the gearbox section. The magnetic field is adapted to move at least one ferromagnetic particle arranged in the gearbox section towards the measuring area, so that a bridge produced from one or more of the ferromagnetic particles is formed between the two electrical contacts. A measured value is generated based on an electrical parameter between the two electrical contacts. A measure of the criticality of a flight operation is determined on the basis of the measured value.