FLARM: electronic conspicuity explained simply
FLARM is a proprietary electronic conspicuity system, historically developed for gliding. It allows compatible devices to exchange their position and, on certain models, to calculate a collision risk — without however guaranteeing collision avoidance or making an aircraft visible to any other traffic.
What is FLARM?
FLARM is a proprietary electronic conspicuity system initially created for gliding, now used by a broader range of light aircraft. Compatible devices exchange their position by radio in order to contribute to mutual awareness of surrounding traffic.
How does FLARM work?
A FLARM device can transmit its position, receive that of other nearby FLARM devices, and, on compatible devices only, calculate a predictable trajectory and estimate a risk of proximity in order to issue an alert. This communication takes place directly between devices, air-to-air, without going through ground infrastructure.
The availability and accuracy of this trajectory calculation depend on the model and manufacturer: not all FLARM-compatible devices offer the same level of processing.
Who uses FLARM?
FLARM is very widespread among glider pilots, where it has been a de facto piece of equipment for many years. It is also present in part of light powered aviation and, for certain uses, among helicopter operators. In free flight, some compatible devices also integrate a FLARM function, although this is not systematic.
FLARM In / Out: what's the difference?
FLARM Out refers to the function of transmitting one's own position to other devices. FLARM In refers to the reception function, allowing surrounding FLARM traffic to be displayed. A given device does not necessarily offer both functions: some models are limited to transmission, others to reception, and others still combine both.
Why is FLARM so widespread among gliders?
FLARM was originally developed to meet the specific needs of gliding, where many aircraft operate in a confined space. Its long-standing and widespread adoption in this field has built up a significant installed ecosystem over the years, which explains its strong current presence among glider pilots.
FLARM in paragliding
In free flight, FLARM is not a universal standard the way FANET can be. Some instruments on the market nevertheless integrate FLARM compatibility, allowing their users to exchange information with gliders or other equipped aircraft. This compatibility depends entirely on the chosen model.
FLARM and FANET+
FANET+ combines the FANET network specific to free flight and FLARM compatibility, the extent of which depends on the implementation chosen by the manufacturer. It is a bridge between the two ecosystems, not a merger of the two protocols.
FLARM and ADS-L
ADS-L and FLARM are two distinct protocols that coexist today in airspace. ADS-L does not replace FLARM: the two meet different needs, and many aircraft continue to use one, the other, or both, depending on their equipment.
FLARM and ADS-B
FLARM and ADS-B are technically distinct protocols, with their own message formats and their own historical uses. See our technology comparison to situate each of them.
Can a FLARM device see an ADS-B aircraft?
Not natively. FLARM and ADS-B rely on different protocols, and a standard FLARM device does not automatically decode an ADS-B signal. Some devices on the market explicitly advertise multi-protocol compatibility ensured by the manufacturer; outside of this case, interoperability between the two systems should not be assumed.
Do all FLARM devices have the same features?
No. Features vary significantly depending on the manufacturer and model. PowerFLARM, for example, is a specific implementation offering advanced traffic display and extended range that are unique to it — these capabilities should not be generalized to all FLARM-compatible devices, many of which offer a more limited level of functionality.
Frequently Asked Questions
No. FLARM provides alerts and traffic awareness on compatible devices, based on what is received and the onboard logic. It is not a system that guarantees collision avoidance, and it does not replace pilot vigilance or air traffic rules.