N° 4–2018: Action plan approved for next Ariane 5 launches

As stated in the Arianespace press release of 23 February, the direct cause of the trajectory deviation on 25 January was an incorrect value provided to the launcher’s two Inertial Measurement Units (IMUs). Given the special requirements of this mission, the azimuth required for the IMU alignment was 70º but the usual value for geostationary transfer orbit missions of 90º was erroneously used instead. This difference led to the 20º shift to the south in the trajectory from the first seconds of flight.

The underlying reasons for the direct cause have been clearly identified: a need to strengthen the processes for establishing, verifying and approving the specific operational procedures involving the IMU reference frame.

Recommendations to improve processes and quality control have been made. Furthermore, additional recommendations to enhance end-to-end verifications of mission-specific parameters used during the launch campaign were made.

ArianeGroup and Arianespace presented their action plan in response to the Independent Enquiry Commission findings and recommendations.

ESA Inspector General Toni Tolker-Nielsen expressed his satisfaction with the presented action plan, which not only addresses the current issue, but a general plan to improve processes and end-to-end verifications, in particular of the few parameters that are not verified because of their nature during the test on the Functional Simulator before each launch.

Thanks to the action plan of ArianeGroup and Arianespace, the reliability of the Ariane 5 launch system, which already had an outstanding series of mission successes establishing it as a market leader, will be further increased.

The actions will enable the next flight of this heavy-lift vehicle to be made this month. 

The Steering Committee mandated the ESA Inspector General to monitor the satisfactory implementation of the action plan of ArianeGroup and Arianespace.

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