Grounding
Very good question, and TOTD is quite correct. At a certain level, the ATC simply won't register as the grounding isn't immediately significant. I think a more interesting question is what remedial action was necessary to prevent the even more frequent imminent groundings, and what the attitude at senior level was.
The obvious ones I can recall are the entire Sea King ASW and SAR fleets in about 1988 and RN Lynx in 1991. It would be more accurate to say the SKs would have still been able to fly, but without mission systems would have been extremely limited; pilot training only was mooted, for about 18 months. (Which some might say is pretty serious). Lynx was a safety critical fire hazard, with aircrew in hospital. Grounding was scheduled for the Monday and we were given the week-end to crack it. I can tell you exactly what the reply from above was - "Let the RN ground their fleet(s) and come begging for money next year". The first was fixed by the marketing director of a well known Design Authority tracking down critical spares in Lagos. (The problem had been identified, but Thompson-CSF had pulled the plug literally at the last minute. They should never have been given another MoD contract). The second by cancelling an RAF contract and using the money to make Lynx safe. (It wasn't expensive, just logistically difficult with about 30 deployed at sea). As I said before, the solution was well known and very simple, but there wasn't any support.