... of events was established: * First 36 seconds of the flight were normal. * At H0+36.7 active SRI declared an operand error. The reason was a software exception, caused by the data conversion from a 64-bit floating-point number to 16-bit signed integer. That conversion can only be applied to a number less than 216, but was applied to a greater number, representing the horizontal velocity of the craft. * On-board computer received from SRI a diagnostic bit pattern, which it tried to interpret as a flight data. The reason why on-board computer could not switch to the back up SRI was that it already shut down for the very same reason as active SRI. And, of course, it would. It was running the very same software as an active SRI. * After receiving a fault report from the SRI, on-board computer considering that to be a proper flight data and realising an unexpected course ...

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