Independent, reproducible monitoring of GNSS interference affecting civil aviation.
Satellite navigation signals reach an aircraft receiver extremely weak — roughly the power of a car headlight seen from twenty thousand kilometres away. They are correspondingly easy to disrupt.
Episodes of degraded satellite navigation affecting commercial aviation over parts of Europe have been reported publicly by airlines, aviation authorities and the trade press. Individual accounts exist. What does not is a continuous, independent, reproducible record of where and when aircraft reported degraded navigation integrity — one built to survive being challenged, and held by someone with no stake in the answer.
GNSS Observatory is being built to be that record.
Aircraft broadcast their position continuously over ADS-B, derived from onboard GNSS receivers. Those broadcasts also carry navigation integrity fields — the receiver's own assessment of how far its reported position can be trusted.
When reception degrades, that self-assessment falls, and the aircraft broadcasts the degradation to anyone listening. The effect publishes its own evidence. We read those public broadcasts and look for populations of aircraft whose navigation integrity falls together, in the same airspace, at the same time — then record the result in a form that can be re-derived and audited later.
A free, openly accessible view of where aircraft have reported degraded navigation integrity.
Open to anyone
Detailed records of individual episodes — airspace, time bounds, the underlying evidence, and the exact software version that produced them.
Airlines · insurers · legal · regulators
A programmatic interface and monitoring notifications, for organisations that need this inside their own systems.
Operations · routing · analytics platforms
A feasibility audit against a full day of real archive data in August 2026 established that the integrity fields the primary method depends on are present at usable density: a median interval of 17 seconds between integrity reports per aircraft, with the relevant field populated on every sample. On an ordinary day, about 5% of reports carry no integrity value — the background rate any real finding has to rise above.
That establishes the data can support the method. It says nothing yet about how well the method works. No findings are published on this site, and none will be until they have been evaluated both against independently documented events and against control airspace where none were reported.
If this would be useful to you, get in touch — and tell us what you would use it for, and what it would replace. That second question is the one that shapes what gets built first.
Most directly relevant to those carrying the consequences: aviation and specialty insurers, underwriters and claims teams, operators assessing route risk, accident and incident investigators, and air navigation service providers. Also to journalists covering the subject.
These are design rules rather than aspirations. They exist because the failure modes are worse than the missed detections — and because they are what allows a finding to survive being challenged.
Aircraft do not spread themselves evenly. They follow airways, so most of this region is watched thinly or not at all — and a cell we cannot see well is a cell we may not make claims about. This map shows where the method can see. It shows no interference findings and is not evidence of any.
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The data processed consists of transponder broadcasts made openly by aircraft: position, altitude, velocity, and navigation integrity values, together with the transponder's assigned address. It contains no passenger or crew information, and none is derived.
Analysis is carried out at the level of airspace and populations of aircraft, not individual flights, and individual aircraft are not identified in the public map or in public findings.
A transponder address can, in some cases, relate to an identifiable person — for example where an aircraft is privately owned. Where it does, processing is carried out on the basis of legitimate interests under Article 6(1)(f) GDPR: the independent documentation of navigation interference affecting aviation safety, using data already broadcast openly and published by others.
You may object to that processing at any time. An owner or operator may request exclusion, and the aircraft will be removed from processing and from any published output. Requests go to the contact address above. A full privacy notice will be published before any findings are.
This site sets no cookies, loads no third-party resources, and performs no tracking.
GNSS Observatory is not an aviation information service. Nothing published here is certified, validated for operational use, or suitable for navigation, flight planning, dispatch, or any safety-of-flight decision. Authoritative information about GNSS availability is issued by the relevant national aviation authorities and air navigation service providers, through NOTAMs and equivalent channels. Always use those.
GNSS Observatory is independent and is not affiliated with, endorsed by, or acting on behalf of any government, aviation authority, air navigation service provider, or aircraft operator.