Quick answer
AOG stands for aircraft on ground. It describes an aircraft that cannot be dispatched until a technical problem is resolved, usually because a part, a repair, or a maintenance action is outstanding. In parts procurement, an AOG label tells suppliers that the request outranks routine work and that speed, accuracy, and documentation all have to hold at the same time.
What AOG means in practice
An aircraft is AOG when it cannot return to service until something is corrected. The trigger may be a component that failed in service, damage found during an inspection, a defect that can no longer be deferred, or a replacement part that did not pass receiving inspection.
The label exists to escalate. Airlines, MROs, and suppliers commonly maintain AOG desks or after-hours contacts so that a grounded aircraft does not wait in a routine queue while schedules, crews, and passengers are affected.
AOG, critical, and routine priorities
Many organizations use a tiered priority scale. AOG sits at the top; terms such as critical or work stoppage usually describe a need that will ground an aircraft soon or is holding up a maintenance check; routine covers planned replenishment.
Definitions vary by operator, supplier, and contract. State the priority and the actual deadline, in local time at the receiving location, rather than relying on the label alone.
What to send with an AOG parts request
The fastest AOG requests arrive complete. Every missing detail becomes a round trip while the aircraft stays on the ground.
- Exact part number, and any alternates your engineering or IPC data already allows
- Required condition and the release documentation your quality team will accept
- Serial-number, modification, or effectivity constraints for the aircraft
- Aircraft location, airport code, receiving contact, and receiving hours
- The latest useful arrival time and who can approve price and logistics decisions
How AOG sourcing gets resolved
A sourcing desk works availability, condition, records, and routing at the same time. Depending on the part and what the operator accepts, the answer may be an outright purchase, an exchange unit, a loan, or an expedited repair.
Transport can range from next-flight-out service to an on-board courier or a dedicated charter for the most urgent cases. The right option depends on part size, dangerous-goods restrictions, customs, and whether someone can receive the shipment when it lands.
Frequently asked questions
What does AOG stand for?
AOG stands for aircraft on ground: an aircraft that cannot be dispatched until a technical issue, part, or maintenance action is resolved.
Is AOG a regulatory term?
AOG is an industry priority term. Operators, suppliers, and contracts define how it is applied, so the deadline and acceptance requirements should always be stated explicitly.
How quickly can an AOG part arrive?
It depends on where the part is, its condition and records, transport options, customs, and receiving hours. A responsible supplier confirms those details before committing to a time.
Authoritative sources
This guide provides general procurement information and is not legal, customs, engineering, or airworthiness advice.
ANAC (Brazil) aviation glossary: AOG FAA AC 20-62E: Eligibility, Quality, and Identification of Aeronautical Replacement Parts