PURPOSE: To perform the automatic horizontal elevation of an aircraft at the time of its inspection/maintenance easily and safely by controlling the operation of plural jacks by a controller on the basis of the detection signal of an inclination sensor addedly provided at the aircraft.

CONSTITUTION: In an aircraft, for instance, a helicopter 10, a pair of hydraulic jacks 1a, 1b are disposed at both bilateral sides, as well as one jack 3 is disposed at the rear part, and an inclination sensor 4 is disposed at an appropriate place. The hydraulic jacks 1a, 1b are respectively connected to air-driven hydraulic pumps 2a, 2b. The air driven hydraulic pumps 2a, 2b as well as the jack 3 and inclination sensor 4 are connected to a controller 9. At the time of performing the automatic elevation of the helicopter 10 while maintaining its horizontality for its inspection/maintenance, the respective jacks 1a, 1b, 3 are independently or jointly operation controlled by the controller 9 on the basis of the detected output of the inclination sensor 4.