C-DRONE GUIDE · 20 SEPTEMBER 2026
Malicious drone detection on a sensitive site: technologies, legal framework, price
A drone hovers over a Seveso site, an aerodrome or a sensitive construction site, and nobody knows who is flying it. The instinctive reaction — bringing it down or jamming its link — is almost always the wrong one: French law strictly reserves the neutralisation of an aircraft to authorised state services, whatever the perceived legitimacy of the threat. What a company can install itself, on the other hand, is a detection system: radar, a radio-frequency sensor, an acoustic array or a camera paired with AI-based classification. Here is how these technologies work, where their limits lie, and above all exactly where what a company is allowed to do alone stops.
Published on 20 September 2026, reviewed on 20 September 2026 — regulations in force as of September 2026.
Why Remote ID falls short against a genuinely malicious drone
Most commercial drones continuously broadcast a Remote ID signal, readable within seconds with a free app: operator number, aircraft position and pilot position. Our guide on how to identify the pilot of a drone flying over your site covers this method in detail, which is enough in the vast majority of cases — a curious onlooker, a contractor unaware of a restriction, a clumsy neighbour.
Remote ID, however, only works if the aircraft broadcasts it. A drone genuinely engaged in industrial reconnaissance, in dropping contraband over a prison, or in scouting ahead of an intrusion has, by construction, no reason to comply with that obligation — modified firmware, an older unit with no such capability, or the signal simply switched off. It is precisely in that scenario — where software-based identification fails — that physical detection systems take over.
Radar, radio-frequency, acoustic, optical: four technologies, four limits
No detection technology is complete on its own; professional systems almost always combine several sensors.
- Radar: detects any flying object, including a drone emitting no radio signal at all, day or night and in poor weather. Its limit lies in target size: a 2020 literature review published in Sensors by Coluccia, Parisi and Fascista notes that the radar cross-section of a consumer multirotor drone is very small, comparable to that of a medium-sized bird — which explains this technology's false-alarm rate and the need for dedicated classification algorithms to tell a quadcopter apart from a buzzard (see the study on Google Scholar).
- Radio-frequency (RF): passively listens to the spectrum to pick up the control or video link between the drone and its remote, which often also locates the pilot. Ineffective against a drone programmed to fly fully autonomously, with no active link at all.
- Acoustic: a microphone array recognises the sound signature specific to rotors. Short range (a few hundred metres at best) and sensitivity to ambient noise make it a complement rather than a standalone solution, useful in dense urban areas where radar and RF get saturated.
- Optical and infrared, with AI-based classification: a camera visually confirms an alert raised by another sensor and tells a drone apart from a bird or a balloon, but stays dependent on line of sight and light conditions.
In practice, a professional system fuses these sources to cut false alarms and cover the blind spots each technology has on its own.
The honesty clause: detection is allowed, neutralisation stays a state monopoly
The honesty clause. Installing a radar, an RF sensor or an acoustic array to detect a drone is perfectly legal for a company. Trying to neutralise it yourself — jamming it, intercepting its link, netting it, let alone destroying it — is not. Article L. 33-3-1 of the French postal and electronic communications code bans the import, possession and use of any device designed to render radio equipment inoperative; the exemption applies only to the needs of public order, defence, national security or the public justice service — no private company, however exposed, falls within that scope. Breaching this ban carries six months' imprisonment and a €30,000 fine (article L. 39-1 of the same code), whatever the legitimacy of the intent.
The paradox is worth pointing out: the pilot of a drone illegally flying over a restricted zone risks up to one year's imprisonment and a €75,000 fine under article L. 6232-4 of the transport code (stemming from the 24 October 2016 law on civil drone safety) — a penalty bracket ultimately not far from what the "victim" company would risk by taking justice into its own hands with a jammer. What the law expects from that company instead is different: detect, document (timestamp, flight path, the detection system's own recordings — all usable evidence) and report to the gendarmerie or police, escalating to the préfecture for the most sensitive sites. Our guide on the bailiff's report backed by a drone survey explains how to turn such recordings into evidence admissible in proceedings.
Who equips themselves, and 2026 detection system prices
Demand comes from upper-tier Seveso sites, from aerodrome and airport operators, from organisers of major events and summits (a temporary system rented for the duration of the event), from defence subcontractors falling under the critical infrastructure operator regime, and from data centres and industrial sites exposed to the espionage risk described in our guide on a drone flying over an industrial site. Prisons follow a separate logic: the Ministry of Justice deploys its own systems there under a national plan, with no need for the facility itself to equip.
Ranges observed in France in 2026, excluding VAT:
| Service | Observed price (excl. VAT) |
|---|---|
| Aerial vulnerability audit of a site (blind-spot survey, sensor recommendations) | €1,500 to €4,000 |
| Fixed RF sensor, range of a few kilometres | €8,000 to €25,000 installed |
| Compact short-range radar (industrial site, limited perimeter) | €15,000 to €40,000 |
| Mobile acoustic solution (events, temporary deployment) | €500 to €1,500 per day of rental |
| Monthly monitoring and supervision of the system | €300 to €1,000/month depending on the number of sensors |
These figures cover the detection hardware itself, not a neutralisation mission, which stays outside the scope of any private provider. As a complement to a fixed detection system, a one-off aerial surveillance mission by drone — to assess the state of a perimeter or document an incident that has already occurred — remains a service we provide. The regulatory information on this page reflects the rules in force in September 2026. For any question about securing your site's airspace, request a quote.