Friday, February 1, 2008
http://www.aviationtoday.com/av/categories/military/18859.html
Opinion Allows Flexibility In Pilot Headsets
Airline pilots have embraced a wide variety of active noise reduction (ANR) products to improve communications and protect their hearing in relatively high-noise cockpits such as the ubiquitous
Boeing 737. A popular ANR application combines the Bose QuietComfort 2 (QC2) headphones with the UFlyMike boom microphone adapter (UFM) designed by retired Southwest captain Mike Lackey.
The UFlyMike adapter plugs into the existing headphones jack without modifications, says UFlyMike, based in Colorado Springs, Colo. The adapter had passed testing requirements of Technical Standard Order (TSO)-C139 and was awaiting
FAA certification.
Several thousand airline pilots have found this combination offers optimum noise reduction while providing exceptional clarity in the 83 to 88 dBA ambient noise environment found in the 737 and several other aircraft.
In early 2007,
FAA inspectors within the certificate management offices of two major airlines objected to pilot use of the QC2/UFMs, ostensibly claiming that airline pilots could use only headsets authorized by FAA TSO. Eight months after receiving a request for clarification, the FAA’s Office of the Chief Counsel responded that federal regulations do not prohibit airline pilots from using non-TSO’d products to supplement already-installed communication equipment that meets minimum requirements.
According to a letter dated Oct. 12, 2007, and signed by Rebecca B. MacPherson, FAA assistant counsel for regulations: "There is no specific requirement that aircraft operating under 14 CFR, part 121 be equipped with headsets or that flight crewmembers use headsets produced under a TSOA (TSO authorization).... Use of a non-approved headset to supplement the operation of an aircraft equipped in accordance (with) those regulations would not... be considered a regulatory violation."
Airline pilots do not have to use headsets at all, but they do have to use boom microphones below 18,000 feet. One major airline’s minimum equipment list (MEL) allows pilots to substitute their own personal equipment for installed equipment, and
Boeing’s 737 operating manual allows the use of "any standard microphone." In this context, "standard" is permissive; it means "commonly used or supplied."
Some FAA inspectors object to use of the QC2s because the headphones require some minimum voltage from one AAA battery to keep the earcup circuit closed. They argue that if the battery dies, the earcups also die and the pilot cannot maintain communication. FAA "is particularly concerned," MacPherson said, "that Active Noise Reduction headsets and headset adapters used by flight crewmembers that rely on battery power are subject to failure when internal or externally connected batteries discharge under normal use. These headsets therefore may not be capable of providing the continuous, uninterrupted communications capability necessary for safe operation of the aircraft."
Pilots who use the QC2/UFM setup counter that QC2s provide plenty of warning beforehand, while substantially reducing communication-related risks.
First, a steady red LED in the right earcup starts flashing when a minimum battery life of five hours remains. Second, if the pilot ignores the flashing LED, he cannot miss obvious aural changes when the ANR circuitry starts cutting out as battery voltage approaches zero. Third, battery condition has no effect on the boom microphone. Finally, should the earcup circuit open, the pilot maintains communication by turning up the cockpit speaker and pulling back one earcup just as he would with any other headset-earpiece failure.
Using the risk assessment guidelines contained in FAA Advisory Circular 120-92 to assess the QC2/UFM setup reveals that the likelihood of failure is very low and the severity of consequences borders between negligible and minor, which places their use well within an acceptable risk range. Compared with the missed or misunderstood communications that occur on every flight, pilots find the QC2/UFM benefits far outweigh the risks. —
Mitch Whatley
Mitchell R. Whatley is an attorney in Southlake, Texas, and a 737-800 captain with a major U.S. airline.
(Contacted by
Avionics, Bose Corp. said it does not endorse the use of the QC2s by pilots, or their compatibility with another manufacturer’s product. The company issued this statement:
"The Bose QuietComfort 2 headphones are designed for noise reduction while listening to entertainment channels in air transport aircraft, such as audio or movie sound channels, and should not be used as a headset for communicating with air traffic control. They are not engineered to meet the needs of pilots and do not meet civil aviation authority standards for communication headsets. Given this, we can not endorse the inclusion of the Bose QuietComfort 2 headphones in your story on aviation headsets in this context or in regards to its compatibility with another manufacturer’s product, like UFlyMike.
The UFlyMike product enables an external source to provide music playback into the QC2 headphones without priority muting or control of received aircraft radio, air-traffic control directions or cockpit intercom communications. This design may allow music to mask critical cockpit communications.
Bose also does not recommend this type of usage with the QC2 headphones because no incoming audio will be heard with a discharged or improperly installed battery. This shortcoming could result in the potential of missed air-traffic control communications while piloting an aircraft. For pilot use, we recommend the Bose Aviation Headset X. The product is TSO-approved and features a microphone with the appropriate power and intelligibility for transmission and reception of flight information. It is engineered to withstand the altitude and temperature conditions common in non-commercial aircraft.")