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PAPI Lights Inspection and Calibration Check by Drone
Drone PAPI inspection. Each unit's transition angle, colour, intensity balance and surveyed position measured, with a same-day protocol to ICAO, EASA…
NOV 17 2025
13 MIN
INSTRUMENT LANDING SYSTEM · RADIO NAVIGATION
In development
ILS flight inspection by drone, run by run
The service is in active development. The vertical passes and arcs an instrument landing system (ILS) check needs are flown today for the PAPI, with real-time kinematic (RTK) positioning. Recording the localizer and glide path signal along them is the part being built, to take over aircraft runs where your authority accepts it.
Schematic, generic airport · illustrative values
built
vertical passes and arcs, flown today for the PAPI
signal
ILS receiver and processing in development
RTK ±1 cm
position of every profile and arc
180 days
nominal ILS flight inspection periodicity in ICAO guidance
FIT
Who this is for
An ILS is flight inspected on a fixed cycle, with an aircraft that has to be booked, ferried and paid by the hour. The service is aimed at the runs a drone can fly as well or better, close to the antennas and to a known position.
For
Air navigation service providers who fly ILS flight inspection on the nominal 180-day cycle and want fewer aircraft runs, with the signal environment still under control.
Aerodromes commissioning, relocating or re-siting an ILS. Checks close to the antennas before the flight inspection aircraft arrives shorten its time on the adjustment.
Navaid maintenance teams chasing an intermittent alarm or a suspected reflection near the antennas, who need the signal mapped close in at a known position.
Not for
Certifying an ILS for operational use today. That stays with the flight inspection organisation and its aircraft until an authority accepts a drone result for a given run.
Adjusting the transmitters or the antenna arrays. That is the work of the provider's navaid engineers, and the measurement stays independent of it.
The far approach, from about 1.5 km before the threshold out to the edge of coverage. A drone flown in visual line of sight does not reach it.
JUDGED ON DELIVERY
Outcomes and acceptance criteria
Three outcomes carry the service. The first can be checked today. The other two depend on the receiver and the processing that are still in development, and the page says so.
01
Profiles and arcs flown to RTK
Vertical profiles at fixed distances in front of the glide path antenna and arcs at fixed radii from the localizer. They are planned from the airport model and flown with RTK positioning, as for the PAPI today.
Acceptance
The flight record shows every profile and arc with its planned and flown positions.
02
Localizer and glide path read from the signal
The recorded signal along each pattern turned into path angle, course alignment and displacement sensitivity. This step is in development.
Acceptance
The trial scope states which parameters were measured and which were not.
03
Correlation with the aircraft
Each drone result set beside the aircraft's result for the same parameter from the same period. ICAO guidance asks for this evidence before a run is dropped.
Acceptance
For every parameter in scope, the drone and aircraft figures sit in one table with their difference.
What the service does not do is certify the facility, adjust it or reach the far approach. Those stay with the flight inspection organisation, the provider’s engineers and the aircraft.
The PAPI and ILS harmonisation row is already part of the PAPI inspection , computed today against the published or flight-inspected glide path.
SCOPE AND DELIVERABLES
What is inside the check
Each part with what it contains and its state today, including the parts that are deliberately outside the scope.
9 parameters
ICAO Doc 8071 Vol. I · Annex 10 Vol. I
Item
What it is
State
01
Flight patterns
RTK-positioned vertical passes, horizontal arcs and approach descents, planned and validated in the platform and flown today for the PAPI.
State
Built
02
ILS in the airport model
Glide path and localizer antenna positions, the published path angle and reference datum height, and a measured angle from a calibration protocol.
State
Built
03
PAPI and ILS harmonisation
The measured PAPI angles compared with the published or flight-inspected glide path, as a row of the PAPI protocol.
State
Built
04
ILS receiver on the drone
A payload that records the localizer and glide path signal with the drone's position and time.
State
In development
05
Glide path parameters
Path angle and displacement sensitivity from vertical profiles at fixed distances.
State
In development
06
Localizer parameters
Course alignment and displacement sensitivity from arcs across the course.
State
In development
07
Correlation report
Drone and aircraft results for the same parameters side by side, for the provider and its authority.
State
In development
08
Far approach
Not included. Beyond about 1.5 km before the threshold the aircraft stays the method.
State
Excluded
09
Certification and adjustment
Not included. The flight inspection organisation certifies and the provider's engineers adjust.
State
Excluded
Measuring the ILS signal is in development. No accuracy, parameter list or authority acceptance is claimed for it yet, and nothing on this page is a flight inspection result.
DELIVERY · 6 STEPS
From the flight inspection programme to correlated runs
01
Trial conversation
You describe the facility, its category, how its flight inspection runs today and which runs you would most like to fly less. We agree the parameters, the windows and how the results reach your engineers and your authority. Output is a written trial scope.
02
Airport model
The glide path and localizer antenna positions and the published glide path angle and reference datum height go into the airport model. This step is built.
03
Planning and coordination
Vertical profiles and arcs are computed from the antenna positions and validated against the obstacles in the model. The tower and the provider agree them, including which runs fall inside the critical areas. Output is a validated mission and confirmed windows.
04
Capture, in development
The drone flies each profile and arc on RTK while the receiver records the signal. The flying is built. The receiver is in development, so on a trial it is run where it is ready and the scope says so.
05
Processing, in development
The recorded signal is turned into path angle, course alignment and displacement sensitivity, each tied to the positions it was measured at. This step is in development.
06
Correlation and delivery
The drone results land beside the aircraft's results for the same parameters, with the flight record and the raw signal retained. A disputed figure is then re-examined, not re-flown.
A PAPI mission on the map: a horizontal arc across the extended centre line, a vertical pass and the approach line to the runway
EVIDENCE AND CAPABILITY
Where a drone fits in an ILS programme
An instrument landing system is verified twice. Ground checks and monitors watch it all the time. A flight inspection aircraft flies it on a cycle, nominally every 180 days in ICAO’s guidance, through the signal a receiver on approach sees. The aircraft is the only method that sees the whole approach. It is also booked, ferried and paid by the hour, and much of its time near the airport goes on runs a drone can fly.
The glide path is the clearest case. Its angle is read where the signal balances. A drone can climb through it at a fixed distance from the antenna, hold the profile to RTK precision and repeat it at night. The localizer course is read on an arc at a fixed radius from the array. The guidance EUROCONTROL presented to ICAO in 2026 describes small drones flown in visual line of sight as a complementary ground maintenance tool, mature in some States. They sample the signal better than an aircraft and fly trajectories in places an aircraft cannot.
The replacement path runs through the sixth edition of ICAO Doc 8071 Volume I. It adds guidance on flying fewer flight inspection runs, mainly for the ILS, and one of its four State examples uses drones. Its first condition is a demonstrated good correlation between measurement methods. The others are stricter tolerances, a safeguarded environment, evidence of stable equipment and careful change management. A drone run that correlates with the aircraft’s run is how a run comes off the aircraft’s list.
What the drone does not replace is the rest. ICAO notes that some antenna faults and some propagation issues can only be found by flight inspection. A drone in visual line of sight does not reach the far approach. A commissioning flight inspection and the runs that look at the whole approach stay with the aircraft. The drone takes the runs close to the airport, and the aircraft flies fewer of them.
PRICING
Not offered yet
This service is in active development and is not offered yet, so there is no price, rate or quote. Four things shape a trial instead.
EUR
not offered yet
excl. VAT
EU
Checked 2026-11-11
Cost driver 01
Facility
Which localizer and glide path are in scope, their category and whether the runway has an ILS at both ends.
Cost driver 02
Parameters
Which parameters the trial measures, which sets how many profiles and arcs are flown.
Cost driver 03
Windows
How long the facility can be taken out of operational use for runs inside the critical areas sets how many visits a trial takes.
Cost driver 04
Travel
Travel to the aerodrome, and whether the visit is shared with the PAPI and the other lighting systems.
A correlation trial is most useful when it runs in the same period as a scheduled flight inspection, so both methods see the same facility. To follow the development or take part in a trial, talk to us
.
EACH WITH AN OWNER
Risks and dependencies
Four things can stop a run or weaken what it shows, and each has an owner.
Owner · WEATHER
Wind and weather
A drone is more limited by wind than an aircraft, and a profile flown in gusts is a noisier profile. Runs are planned for calm windows and repeated rather than kept when the record shows the drone off its path.
Owner · TARMACVIEW
Positioning
Every result is only as good as the position it was measured at. RTK depends on GNSS (global navigation satellite system) signals, and GNSS interference is a known problem around some airports. The flight record carries the positioning quality of each run. A run without a fixed solution is not used.
Owner · PROVIDER AND TOWER
The drone near the antennas
A drone inside the ILS critical and sensitive areas can disturb the signal an aircraft on approach is using. Runs inside them are flown only in agreed windows, usually with the facility out of operational use.
Owner · AUTHORITY
Acceptance
A drone result replaces an aircraft run only where the authority accepts it, and that differs between States. The correlation report is built to support that decision, not to make it.
Accountability sits with TarmacView for the flying, the positions and, once delivered, the measurement. It sits with the provider for the facility, its adjustment and its monitoring, and with the flight inspection organisation and the authority for certification. Nothing on this page is a compliance statement.
Frequently Asked Questions
- Does a drone replace the ILS flight inspection aircraft?
- Run by run, where an authority accepts it, and not all at once. The sixth edition of ICAO Doc 8071 Volume I adds guidance on reducing the number of flight inspection runs. Its first condition is a demonstrated good correlation between the measurement methods. A drone run that correlates with the aircraft's run is what lets a State drop it. ICAO also notes that some antenna faults and propagation issues can only be found by flight inspection, so the aircraft keeps those runs.
- What is actually built today?
- The flying. The platform plans and flies RTK-positioned vertical passes, horizontal arcs and approach descents for the PAPI. An ILS check needs the same patterns. The airport model already holds the glide path and localizer antenna positions and the published path angle and reference datum height. It also holds a measured angle from a calibration protocol. Recording the ILS signal along those patterns and turning it into localizer and glide path parameters is in development.
- Which parameters would the drone measure?
- The ones the aircraft measures near the airport, read from the difference in depth of modulation along a known path. On the glide path, a vertical profile at a fixed distance gives the path angle where the signal balances. The points where it reaches the sector edges give the displacement sensitivity. On the localizer, an arc across the course gives course alignment and displacement sensitivity. The exact parameter list for a trial is agreed with the provider at scoping.
- How far from the runway can a drone measure?
- On or near the aerodrome, in visual line of sight. The flight inspection guidance EUROCONTROL presented to ICAO in 2026 shows a drone check at 1.5 km from the threshold. It reaches close to the far field of the glide path and covers the short final. The drone does not reach beyond that. Larger fixed wing drones that fly complete flight inspection trajectories are established in only a few States so far.
- Has any authority accepted drone ILS measurements?
- Yes, for ground inspection. A Rohde and Schwarz case study reports that Italy's ENAC authorised Techno Sky to perform UAV-based VOR and ILS ground inspections at all Italian civil airports. In July 2022 it added ILS inspection beyond visual line of sight at all single runway airports. ICAO has agreed a job card for UAS-based flight inspection. Whether your authority accepts a drone result in place of an aircraft run is a question for that authority.
- How does this relate to the PAPI and ILS harmonisation check?
- Today the harmonisation row of a PAPI protocol compares the measured PAPI angles with the ILS glide path angle and reference datum height, published or flight-inspected. It is not a measurement of the ILS signal. Once the ILS service is released, the glide path angle in that row can come from a drone measurement on the same visit. Both sides of the comparison are then measured with the same positioning.
- Does the drone disturb the ILS while it measures?
- It can, which is why the flights are planned with the provider. Any object inside the ILS critical and sensitive areas can disturb the signal an aircraft on approach is using, and a drone is no exception. Profiles and arcs inside those areas are flown only in windows the tower and the provider agree, usually with the facility out of operational use. The plan states which runs fall inside them.
References
- icao-doc-8071
- Doc 8071, Manual on Testing of Radio Navigation Aids, Volume I: Testing of Ground-based Radio Navigation Systems International Civil Aviation Organization
- icao-annex-10-v1
- Annex 10 to the Convention on International Civil Aviation, Volume I: Radio Navigation Aids International Civil Aviation Organization
- eurocontrol-icao-2026
- ICAO Provisions and Guidance on Flight Inspection EUROCONTROL, presented at the ICAO MID Workshop on GNSS and PBN
- rs-techno-sky-uav-inspection
- Case study: Techno Sky Air-Nav Ground Inspection Rohde & Schwarz
Reviewed by Štefan Moravík · 2026-11-11
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Talk to us about the development
This service is in active development and is not offered yet. If you run an ILS and want to follow it or take part in a correlation trial, write to us. Tell us the facility, its category and how its flight inspection runs today. Nothing is binding.