Key Insights
- One drone near a runway grounds an entire airport. Gatwick 2018: 1,000+ cancelled flights, 140,000 stranded passengers, £50M+ in losses — and no drone was ever recovered.
- In autumn 2025 alone, drone sightings shut Copenhagen, Oslo, Munich, Brussels, and others — some triggered by sightings that were never confirmed as drones at all.
- Passive acoustic detection confirms a real drone against a false alarm, catches what radar and RF miss, and works at night without adding emissions near aviation systems.
One drone near a runway can ground an entire airport. A collision with an aircraft is catastrophic, so controllers suspend operations the moment a drone is reported. A single sighting cascades into hours of diversions, cancellations, and stranded passengers.
Passive acoustic detection places sensors around the runway and approach paths to detect drones early, confirm whether a threat is real, and give operations the information to keep flying safely. It catches small and autonomous drones, works at night, and tells a genuine drone from a false alarm.
The cost of a single drone
The disruption is severe and repeated. In autumn 2025, a wave of drone sightings shut major European airports in sequence: Copenhagen closed for nearly four hours on 22 September, affecting around 50 flights. Oslo halted the same night. Munich suspended operations twice within 24 hours on 2 and 3 October, cancelling 17 flights and disrupting nearly 3,000 passengers. Aalborg, Alicante, Brussels, Liège, and Vilnius followed through October and November.
The template was Gatwick in December 2018, when repeated sightings brought one of Europe’s busiest airports to a standstill for nearly three days. The toll: more than 1,000 cancelled flights, roughly 140,000 stranded passengers, and combined losses above £50 million. No drone was ever recovered.
That last detail matters. Danish police described the Copenhagen operator as capable — flying in and out of radar range and switching the drone’s lights on and off to evade detection. Several 2025 shutdowns were triggered by sightings that investigators could never confirm as drones. That points to a detection problem, not only a drone problem.
Why airports struggle to detect drones
Airports combine high stakes with hard detection conditions:
- Radar was built for aircraft, not small drones. A sub-2 kg drone reflects almost nothing, and flying low it hides in ground clutter. The Copenhagen operator reportedly moved in and out of radar range deliberately.
- The threat comes at night. Cameras need light and line of sight, and the airport approach is large and dark.
- Autonomous drones carry no radio link. RF detection intercepts a pilot’s control signal. A pre-programmed or fiber-optic drone transmits nothing to catch.
- Jamming near a runway is dangerous and restricted. Interfering with signals around aviation systems is not an option for a civilian airport.
- False alarms are expensive too. When operators can’t confirm whether an object is a drone, a star, or a balloon, they shut down anyway. Every unnecessary closure carries the same cost as a real one.
Why acoustic detection fits airports
Passive acoustic detection answers both problems: missed drones and false alarms.
An acoustic signature is positive evidence that a powered drone is present. That lets operations distinguish a genuine incursion from a false sighting and avoid needless shutdowns. Small, low-flying, autonomous, and fiber-optic drones all produce motor noise — the one signature every powered drone emits, and the one radar and RF both miss.
Sound doesn’t need light or a clear sightline. The sensor only listens — it emits nothing and jams nothing, so it introduces no interference near sensitive aviation systems and needs no RF license.
Airport boundaries run for kilometers. At low thousands per sensor, coverage grows by adding nodes rather than by unit price. A large perimeter is covered by a mesh. Askalon field tests reached 1 km detection on a 1 kg drone.
On detection, the sensor pushes an alert to a control room and staff phones, compressing the time between a drone appearing and a decision being made.
Acoustic detection works best as a wide-area passive layer, often paired with optical for visual confirmation. It does not replace air-traffic radar for tracking aircraft. Very high ambient noise at the runway edge shortens range — sensor placement is designed to manage that.
What to look for in an airport drone detection system
- Detection of small and autonomous drones, not only radio-controlled ones.
- Positive confirmation that a sighting is a real drone, to cut false shutdowns.
- No emissions and no jamming, for safe operation near aviation systems.
- Reliable night performance without dependence on line of sight.
- Coverage that scales across a multi-kilometer perimeter at reasonable cost.
- Real-time alerting into airport operations and security.
Frequently Asked Questions
Why does one drone shut down a whole airport?
A collision between a drone and an aircraft can be catastrophic, so controllers suspend takeoffs and landings as soon as a drone is credibly reported. The safety rule is strict — which is why a single sighting causes hours of disruption, not minutes.
Can radar detect small drones near airports?
Poorly. Small drones carry little metal and barely reflect radar. Flying low, they blend into ground clutter. In the 2025 Copenhagen incident, police said the operator deliberately moved in and out of radar range.
How does acoustic detection reduce false airport shutdowns?
An acoustic signature is direct evidence that a powered drone is present. Operators can confirm a real incursion rather than closing the runway on an unverified sighting that later turns out to be a bird, a balloon, or a distant aircraft. That confirmation is the difference between a necessary shutdown and a costly false alarm.
Is acoustic drone detection safe to use near aircraft?
Yes. It only listens and emits nothing, so it creates no radio interference near aviation systems and requires no transmission license — unlike radar or jamming.
Bottom Line
One drone near a runway can shut an airport for hours and cost millions. The problem is getting worse: autumn 2025 saw a wave of shutdowns across Europe, some triggered by sightings that were never confirmed as drones. Airports need detection that catches what radar and cameras miss, confirms a real threat against a false alarm, and operates safely near aviation systems. Passive acoustic detection does all three.
If you’re responsible for airport operations or security, get in touch — we’ll help you understand what coverage looks like for your airfield.
Last updated: July 2026. Reviewed by the Askalon Industries engineering team. Askalon Industries builds passive acoustic drone detection sensors in Lausanne, Switzerland.
