Ariane 5 - Dependability Study

The Ariane 5 launcher accident

This case study describes the accident that occurred on the initial launch of the Ariane 5 rocket, a launcher developed by the European Space Agency. The rocket exploded shortly after take-off and the subsequent enquiry showed that this was due to a fault in the software in the inertial navigation system. In June 1996, the then new Ariane 5 rocket was launched on its maiden flight. It carried a payload of scientific satellites. Ariane 5 was commercially very significant for the European Space Agency as it could carry a much heavier payload than the Ariane 4 series of launchers. Thirty seven seconds into the flight, software in the inertial navigation system, whose software was reused from Ariane 4, shut down causing incorrect signals to be sent to the engines. These swivelled in such a way that uncontrollable stresses were placed on the rocket and it started to break up. Ground controllers initiated self-destruct and the rocket and payload was destroyed. YouTube video of the explosion (25 seconds, external link)

Supporting documents

System overview ( PPTX) Report of the accident enquiry board (HTML) The Ariane 5 Accident: A Programming Problem? (HTML). A detailed analysis of the causes of the accident.


Each student will prepare and present an analysis of this failure. The assignments and objectives are listed below. In each case the student will prepare a 10 minute presentation, including slides, to present in class. The presentation should use the material provides here, along with concepts from the text, and at least 3-5 other significante references germain to the topic. There is a selector on Moodle for picking which you want to do.

1. Ariane 5 - System Flaws

How did the system fail? Give a detailed, but clear, explaination of the series of events within the system that lead to the failure. This is specificially focused on the time from 10 seconds before the launch to 40 seconds after.

2. Ariane 5 - Engineering Process Flaws

What chain of engineering actions and choices lead to the creation of a flawed system? Describe in detail what situations and actions lead to the creation of a system that would fail in such a way. Consider ALL the steps that lead to failure, and coorelate them with bad engineering processes.

3. Ariane 5 - Fault Tolerance

How could the system have been designed and implemented to avoid the the consequence of the failure? Assume the error still is present in the sytem. Are there design differences that would have allowed the system to not fail despite the flow? Giver 2-3 possible solutions., and justify them.

4. Ariane 5 - Fault Avoidance

Purpose in detail steps and methodologies that would have avoided the introduction of these errors into the system. Be specific, and tie these methids to particular methods in the text, or elsewhere.

-- JimSkon - 2012-03-30

Topic revision: r2 - 2016-09-20 - JimSkon
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