An Atlas Air Boeing 747-400, registration N480MC performing positioning flight 5Y-2868 from Manchester, EN (UK) to Orlando, FL (USA) with 20 crew on board, was enroute at FL380 about 220nm westsouthwest of Shannon (Ireland) about to enter Oceanic Airspace when the crew entered a hold to work on a problem.

After about an hour the crew decided to divert to Shannon advising they had suffered a system malfunction that rendered them non-compliant with reduced vertical separation minima (RVSM) criteria. The aircraft landed safely on Shannon’s runway 24 about 100 minutes after entering the hold.

The aircraft, bound for Orlando to perform a relief flight for stranded Thomas Cook holiday makers, remained on the ground for about 16 hours, then continued the flight to Orlando.