Aircraft on ground

Aircraft on ground or AOG is a term in aviation maintenance indicating that a problem is serious enough to prevent an aircraft from flying. This can involve problems as simple as a light bulb being out or as complex as a damaged engine. Boeing estimates that a 1-2 hour AOG situation will cost an airline from $10,000 to $20,000 and possibly even as high as $150,000 per hour depending on the type of aircraft and route flown.