The airline sent the plan to IFPS which checked it was in the correct format (which it was) and accepted it. IFPS passed it to Swanwick at the appropriate time. There was an anomaly in the route (duplicate fixes) which by NATS' admission the FPRSA-R program logic couldn't handle. NATS says this "led to a 'critical exception' whereby both the primary system and its backup entered a fail-safe mode". Personally I find this hard to believe. If the FPRSA-R was still in control of itself surely it would say "Look chaps - this route looks rather weird. There appears to be a duplicate fix. I'll ignore it for now until you guys figure it out. In the meantime I'll carry on processing all the other flight plans". IMHO 'critical exception' and 'fail-safe mode' are spin for "it crashed".
Last edited by CBSITCB; 6th Sep 2023 at 22:40.
Reason: Typo