MONITORING A SPEED DETERMINATION SYSTEM

A monitoring system for a speed determination system in an aircraft is disclosed. A method, which may be implemented by a computer program, of monitoring a speed determination system for an aircraft is also disclosed. The speed determination system includes a first speed measurement system and a second speed measurement system and the second speed measurement system is associated with a predetermined behaviour characteristic. The monitoring system includes a processor arranged to receive speed data provided by the speed determination system and to perform a correspondence determination process comprising processing the received speed data to determine whether a correspondence condition is satisfied, the correspondence condition having a correspondence between the received speed data and the predetermined behaviour characteristic of the second speed measurement system. In response to determining that the correspondence condition is satisfied, determine that the first speed measurement system is in an error condition.