A goal of mine in 2025 was to tackle a new outdoor sport: backcountry skiing. With the promise of untracked snow and uncrowded runs, venturing off-piste was enticing. But with that also came the need to ensure safety — I geared up with an avalanche kit, most of which was intuitive: Shovel? Check. GPS? Check. But one thing that kept coming up was the RECCO tag on all sorts of gear. As I read the logo time and time again, I wondered — what was this technology?
Skiing safety centers around the risk of avalanche; where there is big snow, there is also the risk of getting stuck in big snow. The daring athletes who go beyond patrolled areas don a few critical pieces of gear: a transceiver or beacon to send out a signal about their location, a probe that snaps together like a tent pole to poke through snow and locate the buried person, and a shovel to then rescue said person. The principle is simple: if buried in mounds of snow, your crew needs to be able to locate you then get you out.
A Rescue Game of ‘Marco Polo’
RECCO reflectors trace their origins to Sweden in the late 1970s, born out of a need to improve avalanche rescue efforts. Over the years, they’ve expanded beyond snowy slopes to include hiking and mountaineering gear, offering peace of mind to outdoor enthusiasts everywhere.
The RECCO system consists of two components: a reflector and a detector. The reflector is a passive device—no batteries, no buttons—sewn into outdoor clothing, helmets, or gear. Inside is a diode and an antenna that respond to radar signals. The detector is a handheld device operated by rescue teams. It sends out radar signals that the reflector bounces back as harmonic echoes, guiding rescuers to the reflector’s location. Harmonic radar, the principle behind RECCO, is like an extra set of eyes for rescue teams. The radar waves interact with the diode inside the reflector, which then re-radiates a signal at double the original frequency. This harmonic echo pinpoints the location of the buried or lost individual.
As such, the RECCO system works much like a high-tech game of "Marco Polo." The handheld detector call “Marco” out by emitting radar signals, while the reflector, embedded in outdoor gear, answers back “Polo” by bouncing the signal back as a harmonic echo. This harmonic radar technology transforms an otherwise silent and disorienting rescue scene into one where rescuers can pinpoint a victim’s location, even in poor visibility or deep snow.
Image by https://www.defencexp.com/explained-how-does-avalanche-rescue-system-works/ .
Tiny Reflectors for the Birds and the Bees
Harmonic radar’s capabilities shine in scenarios like avalanche rescues or low-visibility searches. But this technology is employed elsewhere too — it is a leading method of tracking birds and bugs! Tracking birds through radar dates farther back than tracking humans, with a 1945 paper in Nature outlining that radio waves reflected by birds could be detected by Air Defence and Research and Development equipment. Harmonic radar differs slightly from radar alone because the latter uses linear signals, while the former uses multiple nonlinear signals, which allows for better clutter rejection. This means that harmonic radar is better at detecting what you want while ignoring what you don’t, hence the shift to this technology. Whether it’s fruit flies, moths, or bees, tiny harmonic radar tags can be placed on our flying friends to better understand pollination patterns, flight behavior, and for other surveillance strategies that come into question as animals are impacted by the anthropomorphism of nature and/or climate change.
The application of this technology with the birds and the bees highlights key strengths — it is affordable and therefore possible to tag many animals and run the risk of being lost, and it is light, attaching to these animals without modifying their flight path.
While RECCO acts as safety insurance for us skiers, this system is not a substitute for other safety tools. Avalanche transceivers, for instance, allow for coordinated rescues by enabling two-way communication, while GPS devices provide real-time location tracking. Avalanche airbags serve an entirely different function, helping prevent burial rather than aiding in location. So, when I geared up for the backcountry, I made sure to be equipped with all of the above, because it’s always better to be safe than sorry.
@CatWang