What is a Portable PAPI?
The same red and white slope signal, on temporary legs and its own power. Set up, aimed and checked for each deployment, then removed.
A Portable PAPI gives the pilot the same red and white slope signal as a permanent PAPI. What changes is how it is installed: the units stand on temporary adjustable legs, run from a battery, solar, generator or AC supply, and are placed, aimed and checked for each deployment, then taken away.
1Same signal, different mounting
The pilot reads it exactly as a permanent system: all white is high, one red is slightly high, two red and two white is on slope, three red is slightly low, and all red is low. A portable set may be four units, or two for an abbreviated PAPI (APAPI), which gives a coarser signal: two white is high, one red and one white is on slope, two red is low. It is used on temporary airfields, runways under works, and expeditionary or emergency operations.
2Power that goes where the runway goes
A portable set usually cannot count on an airfield series circuit, so it carries its own supply. A battery kit or solar kit keeps it independent of the airfield circuits, and a generator or AC input can charge or back it up. Some sets add wireless control so the lights can be switched from the ground.
3Set it up correctly every time
A permanent PAPI is set once and then inspected. A portable one is set up afresh at each deployment, so each unit must be placed on the layout, levelled, set to its own elevation angle and aligned with the runway. The four units are set at stepped angles about the approach slope, which is why they change from white to red one after another as the aircraft descends, starting with the unit nearest the runway. A unit that is out of level or at the wrong angle changes the colour the pilot sees at a given height. Some units carry a tilt switch for this reason.
4Secure it, power it, and record it
Legs must be locked and the set secured against wind and jet blast, since a unit that moves has moved the glide path with it. Check that the power source is charged or running, that every unit changes from white to red cleanly, that lenses are clean and beams are clear, and record the settings. A flat battery, a shifted leg or a dirty lens gives the pilot a wrong or missing signal.
| Item | Permanent PAPI | Portable PAPI |
|---|---|---|
| Signal | Red and white, four units | Same with four units; a two-unit set gives a coarser signal |
| Mounting | Frangible mountings, on foundations | Temporary adjustable legs (still low and frangible) |
| Power | Airfield series circuit or mains | Battery, solar, generator or AC |
| Setting | Set at installation, then inspected | Set up and checked each deployment |
Frequently Asked Questions
Q1What is a Portable PAPI?
A Portable PAPI is a PAPI built to be set up temporarily. It gives the same red and white slope signal as a permanent system, but the units stand on adjustable, frangible legs instead of fixed foundations and can run from a battery, solar, generator or AC supply. It is used on temporary airfields, runways under works, and expeditionary or emergency operations.
Q2How does a Portable PAPI differ from a permanent PAPI?
The optics and signal are the same: white above the slope, red below, and a mix of red and white around it. The difference is in how it is installed. A permanent PAPI is fixed on frangible mountings on foundations, fed from the airfield series circuit or the mains. A portable set is placed, levelled, aimed and powered for each deployment, and then removed.
Q3What must be checked when a Portable PAPI is set up?
Check that each unit is level, set to its correct elevation angle (the units are stepped about the approach slope) and aligned with the runway, that the legs are locked and the set is secured against wind and blast, that the power source is charged or running, that every unit changes from white to red correctly, that the beams are clear of obstructions, and that the settings are recorded. Confirm the setting by the method the authority requires.
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