How do Flight Alarms work?

A cyclist is more visible to car drivers wearing bright clothing, and arguably safer. Flight alarms are the digital equivalent of a high-vis jacket. You might not be able to see the aircraft on the other side of a tall cloud, but you could see it on a screen in your cockpit, and your instrument could also make a noise when aircraft get close.

This is the principle at work in commercial airliners, but with a lot more infrastructure. In the seafaring world, locator beacons offer routine conspicuity and improve search and rescue. For commercial aircraft, this has to work all the time and every time, with the attendant astronomical cost. There is a more cost effective solution for gliding (sailplanes, hang gliders and paragliders).

FLARM (FLight alARM) is popular amongst sailplanes. The typical FLARM unit sends and receives signals and calculates the trajectory of nearby air traffic to warn of collision risk. This unit is too large and costly for most freeflight pilots, but for a very small cost to a manufacturer they can make a tiny device that transmits FLARM signals. As the slower moving HG or PG, we really want the faster moving vehicle to see us.

FANET (Flying Ad-hoc NETwork) is a similar lower cost method of transmitting position and sharing information, but not for collision avoidance, as that is a FLARM patent.

FANET+ is a combination of a FANET transceiver and a FLARM transmitter.

Where can I get one?

Skytraxx Beacon

The Skytraxx 2.1 and Skytraxx 3.0 are available in FANET+ versions. If you just want to add conspicuity to your current instrument setup, the cheaper Skytraxx Beacon offers FLARM (Tx) and acts as a flight logger.

You’ll see all the FANET aircraft on the Skytraxx 3.0, but you can actually receive position information from nearby FLARM aircraft as well via the OGN (Open Glider Network) if the unit is fitted with a WiFi dongle and connected to the Internet via a mobile hotspot. However, this information is via a number of relays and is not 100% live.

The Naviter Blade also has these features, and it looks like they will ripple down into future versions of the Oudie. Other manufacturers may follow suit. Also advertising FLARM (Tx) are the XCtracer and AirWhere units.

As FLARM relies on a glider equipped with a receiver, and many gliding club aircraft don’t carry the same, it’s not a guarantee of visibility. It just improves the odds of being seen, as a lot of gliders that are privately owned and flown cross country have the necessary hardware fitted for collision avoidance and moving map navigation.

Who cares?

The Civil Aviation Authority is pushing for ‘Electronic Conspicuity’ (EC) for all airspace users. It’s best that we have our own networks rather than having costly, heavy and unsuitable transponders or ADS-B transceivers forced on us.

Although our best method to stay safe in the air will always be to ‘see and avoid’, we think FLARM (Tx) is valuable, affordable and works when we need it most (close to cloud base, with sailplanes on approach at over 100km/h).

Ruth Kelly adds: “Although the biggest user group is gliders, quite a few powered aircraft also have FLARM (mine does) and still more have Pilot Aware, which is capable of receiving FLARM data. The point being, of course, that any paraglider suitably equipped with one of these FANET devices will be more visible to GA aeroplanes too. Speaking as someone who loves to fly near clouds AND has more awareness than most GA pilots of paragliding I can only say that this is a good thing. Paragliders are devilishly hard to spot and closing speeds can be enormous – I usually cruise at 140-150 knots in my RV8. Making yourself more visible is always a good idea. Happy landings, Ruth.”

Real life example

Skytraxx 2.1 review - FLARM (Tx)

On the early May Bank Holiday, Greg went XC with a Skytraxx 2.1 and Steve saw his location on a smartphone running an app.

He’s visual and clear of cloud. FLARM equipped sailplanes in the immediate area would have had him on their displays. He would also have been visible electronically to sailplanes on http://www.glidertracker.org

Other FANET paraglider pilots could have seen him, as could anyone helping with retrieves. If the device was registered on Livetrack24, then he could be visible on xcrt.aero.

This flight alarm system demands no action or attention from the paraglider pilot – you simply switch on your enabled device, and fly.

Find out more about the Skytraxx range