1, clock calibration, clock calibration with standard time. On the ground, you can use radio, GPS and other equipment to obtain the standard time and adjust the time of the aircraft clock according to the standard time.
2. Timer calibration. Timers are usually used to record the duration of specific events, such as climb time and cruise time. Set the timer to zero, record the standard time, start the timer and record the elapsed time, and then compare it with the recorded standard time to determine whether the timer is accurate.
3, stopwatch proofreading, stopwatch is usually used to calculate a short time interval, zero the stopwatch, and record the standard time, start the stopwatch and record the elapsed time, and then compare it with the recorded standard time to determine whether the stopwatch is accurate.