Starting on Jan. 1, certain piston-powered aircraft registered or operating in the UK will be required to carry an active carbon monoxide (CO) detector. The rules don’t require a certified unit, and both installed and portable CO detectors are acceptable.

Although the rule doesn’t specifically address helicopters, it does exclude “aircraft with piston engines located above/behind the cabin, unless cabin heat is also provided via an exhaust heat exchanger or a combustion heater,” according to the Civil Aviation Authority (CAA). Thus the rule should apply to piston-powered helicopters that use exhaust heat exchangers for cabin heating.

Other exemptions from the rule include single-seat or open-cockpit aircraft, those performing aerobatic maneuvers, and aircraft with wing-mounted engines that do not use exhaust heat exchangers or combustion heaters to provide cabin heat.

The CO detector must provide alerts via aural and/or visual means. According to the CAA, “Detectors can either meet recognized aviation standards (for example ETSO-2C48a) or be commercially available detectors not specifically designed and certified for use in aircraft.”

In a 12-month study of CO detectors, the CAA found that CO alert numbers increase with aircraft age, with 66% of alerts occurring on aircraft 41 or more years old. “However, it is worth emphasizing that CO can be an issue for any aircraft, irrespective of age,” the CAA noted in the study.