FAA issues information on the safety of noise-cancelling headsets

The US National Business Aviation Association (NBAA) has highlighted to its membership a recent information for operators (InFO) alert into the possible safety risks associated with pilots and crew wearing noise-cancelling headsets in the cockpit.

The US Federal Aviation Administration report, Noise Attenuation Properties of Noise-Cancelling Headsets, emphasises the need for operators to evaluate the use of noise-cancelling headsets in the cockpit.  The NBAA represents many operators of small jets and turboprops, many of whom have varying procedures for cockpit headsets including use of pilots' own equipment. The FAA’s Flight Standards Agency is concerned that such headsets may impair a pilot's ability to hear audible alarms and other environmental noises, posing a safety issue that airlines should take seriously. 

At present, the InFO is a voluntary undertaking by operators.

Regular headsets reduce unwanted ambient sounds by physical barriers such as foam, whereas noise-cancelling headsets use both physical barriers and active noise control.  The technology involves a microphone inside the headset, close to the ear and a tiny speaker that produces a sound wave with the opposite polarity of the sound wave arriving at the microphone. Thus cancelling out mainly low continuous noises that the pilot may otherwise hear.

However, the frequency range in which noise-cancelling headsets are most effective varies with the make and model, making the safety issue difficult to access industry wide. Some headsets will eliminate most continuous sounds in the cockpit and significantly reduce other environmental sounds.  This could affect vital communications between flight crew, and pilots hearing other noises, such as aircraft during ground operations, abnormal aircraft sounds, and some audible alarms.

The FAA was not available immediately for comment.  

Source: FlightGlobal.com