An aircraft on the ground is not just an operational problem. It is a financial haemorrhage that starts the moment the wheels stop turning and doesn't stop until the aircraft is back in service. Most people who haven't worked in aviation operations significantly underestimate the real cost — and the airline industry, for its part, doesn't exactly advertise it.
The numbers everyone cites — and why they're wrong
The commonly cited figure for widebody AOG cost is $10,000–$150,000 per hour. That range is so wide as to be almost meaningless. The truth is that the real cost of an AOG depends on the aircraft type, the route it was flying, the time of day, the alternative options available to the airline, and a dozen other variables — most of which are invisible in the headline number.
Direct costs (crew, hotel, catering, APU fuel) are often less than 30% of total AOG cost. Indirect costs — passenger compensation, missed connection rebooking, slot loss, cargo penalties, and brand damage — are where the real money goes.
What actually happens during an AOG
When an aircraft goes AOG, the clock starts immediately. The airline's operations control centre (OCC) begins evaluating options — ferry another aircraft, wet lease, rebook passengers. Simultaneously, the MRO team begins the AOG process: identifying the defective component, sourcing a serviceable replacement, arranging logistics, and mobilising a certified engineer. All of this happens in parallel, under pressure, often in the middle of the night.
The supply chain challenge at the core of an AOG is genuinely hard. Aviation parts are highly regulated — they need traceability documentation, airworthiness certification, and must meet specific part number requirements. You can't just order any pump. You need the right part number, in serviceable condition, with the right paperwork, available right now, and delivered to an airport that may have limited freight connections.
Why some AOGs cost 10x more than others
- ›Outstation vs. hub: an AOG at an outstations airport is far harder to resolve — limited MRO capability, fewer freight connections, no nearby parts pool
- ›Aircraft type: a widebody has more complex systems, rarer parts, and often fewer certified engineers globally
- ›Time of day: an AOG at 2 AM means sourcing a part before opening hours, at premium rates, with limited logistics options
- ›Cascading cancellations: a single AOG can cancel 3–6 downstream flights as the rotation propagates through the day
- ›Slot loss: at slot-controlled airports, a missed slot may not be recoverable the same day — adding route revenue loss to direct costs
The supply chain lesson
Every AOG is, at its core, a supply chain failure — not necessarily a maintenance failure. The part may have been predictably needed (a known life-limited component approaching its limit), but the right part wasn't in the right place at the right time. Pre-positioning of high-demand, hard-to-source components is one of the highest-leverage interventions an airline's technical operations team can make. It's unsexy work — inventory planning, pooling agreements, vendor relationships — but it directly translates to fleet availability and revenue protection.
The best AOG cases I've worked on weren't the ones resolved fastest through heroics. They were the ones that never became AOGs because the right part was already there. Prevention is where the real supply chain value lives.