A synchronizer for coupling a corrective servo mechanism to a pneumatic altitude sensor in an aircraft to provide a display with a positive pressure altitude indication. The synchronizer has a first rotor retained on a shaft with gear teeth that are positively engaged with the servomotor. The synchronizer has a second rotor concentric to said first rotor with gear teeth that positively engage the altitude sensor. A coil in the synchronizer is energized and lines of magnetic flux developed which pass through poles in the first and second rotor. An altitude computing device connected to the altitude sensor computes an electrical error signal which activates the servomotor. With the servomotor activated the first rotor is moved. The magnetic attraction between the poles correspondingly causes the second rotor to move and exert a modifying force on the output from the altitude sensor to establish the true pressure altitude output for operating an indicator.
