Standard, Units & Display
Angles are in degrees and minutes of arc (′) throughout. Changing the length unit converts every length already entered.
PAPI System & Design Settings
Elevation and bearing are optional: leave them blank to skip the elevation-vs-design and azimuth checks.
| Unit | Setting vs θ (′) | Design angle |
|---|
Positive = aimed above θ. Inner unit first. Pre-filled with the common 4-unit pattern (+30′, +10′, −10′, −30′); edit to the approved design. Changing the number of units resets this table.
Tolerances & Corrections
Tolerances are the ± values from the governing standard or project specification. A blank tolerance switches that check off, but the verdict cannot show PASS while the aiming-angle tolerance is blank. The pre-filled values are placeholders, not standard figures — replace them.
Applied to each unit and to the effective glide-path angle.
Direct-angle readings use: aiming angle = reading − index error + housing offset. The housing offset is the manufacturer’s relation between the surface the inclinometer sits on and the optical axis.
Measurements
Horizontal distance from the bar at which angle errors are also shown as a height.
| Unit | Reading (°) | — | Optical-centre elevation | Azimuth (°) | Aiming angle | Δ Angle | Δ Elevation | Δ Azimuth | Status |
|---|
Report Details
Result
Aiming Angles vs Design
Indication Bands (as Measured)
| Indication | Lights | Measured band | Design band | Edge shift (low / high) | Height band at ref. distance |
|---|
Each unit shows white above its aiming angle and red below it. Bands are built from the measured angles sorted from lowest to highest; heights are above the optical-centre plane at the reference distance.
Checks
| Check | Value | Requirement | Status |
|---|
How This Calculator Works
Every unit is reduced to one number, its aiming angle above horizontal. Design angle, deviation, effective glide path and indication bands all follow from that.
Aiming angle
From an inclinometer or theodolite:
From a staff observed at horizontal distance L, with the transition seen at elevation Et and the unit’s optical centre at Eo:
Corrections for index error and housing offset apply to direct readings only. Earth curvature and refraction are ignored, which is acceptable at the short distances used for staff observations.
Deviation and effective glide path
Deviation = measured − design angle, in minutes of arc, positive when the unit is aimed high. The effective glide path is the mean of the middle two measured angles (the middle one for an odd count) and is compared with the nominal θ.
Δh is the height error of the on-slope indication at distance d.
Indication bands
With the measured angles sorted lowest to highest, the band with w white lights lies between the w-th and (w+1)-th angle. Comparing each band edge with its design edge shows how the on-slope sector has moved or narrowed.
Starting values offered
| Item | Pre-filled |
|---|---|
| 4-unit setting pattern (inner first) | θ +30′, +10′, −10′, −30′ |
| 2-unit and 3-unit patterns | 2 units: ±15′ (APAPI); 3 units: +20′, 0, −20′ (placeholder) |
| Aiming angle tolerance | ±5′ (placeholder) |
| Elevation tolerance / height spread | 0.05 m (placeholder) |
| Azimuth tolerance | Blank (not checked) |
The 4-unit pattern is the common ICAO arrangement, offered as an editable starting point only. Confirm every setting and tolerance against the current edition of the governing standard, the manufacturer’s instructions and the approved design before relying on a pass.
Terminology kept separate
Aiming angle (one unit’s optical setting), glide-path angle (the resulting on-slope path), design setting (offset from θ) and deviation (measured minus design) are different quantities. P1 is the unit nearest the runway and has the highest setting; ICAO labels the units A to D from the farthest, so A = P4. Unit position and spacing are checked in the PAPI Unit Separation & Lateral Geometry tool.
What this calculator does not do
It does not replace a flight inspection, check beam cut-off sharpness, intensity, colour or the obstacle clearance surface, and it cannot tell whether an instrument is calibrated. It does not correct the aiming angles for runway longitudinal gradient or cross-slope; apply the correction your standard or the manufacturer requires and enter the corrected nominal angle θ. A PASS means the measured values are within the tolerances entered, not that the PAPI is commissioned.