Your aircraft is AOG. What happens next?

An aircraft on ground is a schedule problem and a cost problem arriving at the same time, and the first hour usually determines how long the whole thing takes. Most of what makes that hour productive is information you already have.

What to report in the first call

The single most useful thing you can do is describe the symptom rather than the diagnosis. A shop hearing “the transponder has failed” will start on the transponder. A shop hearing “ATC reports intermittent altitude reporting, worse in the climb” will consider the encoder and the static system too — and one of those is frequently the actual fault.

• Aircraft make and model. It determines which systems are involved before anything else.
• What was observed, by whom, and under what conditions. Especially whether it is intermittent.
• Where the aircraft physically is, and whether it can be moved.
• The part number, if a unit has already been identified. It tells us availability, exchange options and lead time immediately.
• What has already been tried. Troubleshooting done saves repeating it, and often points straight at the fault.
• Your actual deadline. “As fast as possible” is not a deadline; “it needs to fly Thursday morning” changes the recommendation.

How triage works

The goal of triage is not to identify the fault. It is to identify the shortest credible path back to airworthy, which is a different question and sometimes has a different answer.

Broadly there are three routes: repair the unit, fit a serviceable exchange unit, or send a technician to the aircraft to diagnose in place. A good shop will tell you which is fastest and what each costs, including when the fastest one is not the one they would rather sell you.

Why removing the unit first can cost you time

There is a strong instinct to pull the suspect box and send it away. It feels like progress. But a unit that arrives at a shop, tests fully serviceable and goes back on the aircraft has cost several days and proved almost nothing — and the fault is still there.

Wiring, connectors and interfacing equipment account for a large share of faults attributed to avionics. Diagnosing on the aircraft first, where the fault actually manifests, is very often the faster route even though it looks slower on day one.

What to expect from the shop

• Acknowledgement that the aircraft is grounded, and confirmation that it is being handled ahead of routine work.
• A realistic assessment of the options with honest timelines — including the option they do not profit most from.
• One point of contact, so you are not reconstructing the situation each time you call.
• Proactive updates. You should not have to chase progress on a grounded aircraft.
• Documentation on return, so the next person who sees this symptom has a baseline.

One thing worth doing before you need it

Establish the relationship before the aircraft is grounded. A shop that already knows your fleet, your configuration and your operation triages faster than one starting from a cold call — and the difference is measured in days, at the exact moment days are expensive.