How is a PAPI monitored remotely?
The PAPI reports its state over a link to the control room, so a failed unit is found sooner. The reading is a warning; the signal itself is still proved on site.
A PAPI stands at the edge of the runway, often far from anyone. Remote monitoring brings its state to the control room, so a failed unit shows up as an alarm instead of waiting for the next inspection. It is a view of the PAPI, not a proof of its signal.
1The PAPI reports its own state
The control unit gathers the state of the wing bar: whether it is on, the intensity step, the lamp or LED of each unit with its identity, the supply or CCR, and on some types a drift in aim. What can be seen depends on the PAPI type, the sensors fitted and the control system.
2It travels to the ALCMS and is shown by state
The status crosses a communication link chosen by the design to the ALCMS, which shows it, raises an alarm and logs it. Each state is shown clearly: healthy, warning, fault or unknown. A lost link is unknown, never healthy, because the PAPI may still be working. The link needs cyber-security.
3Treat a reading as a warning, then prove it
An alarm sends an engineer to check the unit, and a clean screen is not a reason to skip rounds. Check that each status matches the real unit, that a lost link is shown as unknown, that alarms raise and clear, and that the log is kept. The colour change and aiming are still verified by inspection, testing and flight checks where required.
| Element | Role | What to check |
|---|---|---|
| Sensing | Lamp or LED, supply and, on some types, aim | Each status matches the real unit |
| Control unit | Gathers status and adds the unit identity | Correct unit shown for each fault |
| Link | Carries status to the ALCMS, securely | Lost link shown as unknown, not healthy |
| Display and alarm | Shows state, raises alarms, clears them | Alarms raise and clear correctly |
| Log | Records events and states over time | Entries kept and time-stamped |
Frequently Asked Questions
Q1What does PAPI remote monitoring show?
It shows the state of the PAPI from outside the airfield: whether it is on and at which intensity step, the health of each unit with its identity, the supply or CCR state and, on some types, a warning that a unit has drifted out of aim. What is available depends on the PAPI type and the control system.
Q2What does it mean if the PAPI link is lost?
It means the status is unknown, not that the lights are healthy or failed. Loss of communication should be shown as its own state and prompt a check, because the PAPI may still be working normally at the site.
Q3Does remote monitoring replace inspection?
No. A remote reading is a warning, not proof. It helps find a failed unit sooner and shows trends, but the colour change and the aiming are still verified on site by inspection, testing and, where required, flight checks.
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