The Duncan Download Blog: Business Aviation Advice & Observations

What Do Unicorns & ADS-B Exemptions Have in Common? Neither Actually Exist

Posted by Adrian Chene on Tue, Oct 27, 2015 @ 11:13 AM

You can always dream, but Automatic Dependent Surveillance-Broadcast (ADS-B) exemptions fall into roughly the same category as unicorns.

When Ringling Bros. and Barnum & Bailey Circus introduced a live unicorn into its lineup in 1985, it created quite a stir. The question that swirled around the animal was whether it was a real horn. Although the horn was real, many people ignored the most important fact; the animal was a goat.

In much the same way, there has been much misunderstanding with regard to a recent ADS-B exemption letter from the Federal Aviation Administration (FAA). Some operators heard ADS-B and exemption in the same sentence and immediately began planning for non-compliance. The reality though is that in 2020 an ADS-B transponder exemption is as likely as Ringling Bros. having an actual unicorn at one of their shows.

The controversy started when Airlines for America, the trade organization that represents the principle U.S. airlines, sent the FAA a request for an exemption. The exemption request indicated that much of the airline fleet was not currently equipped with Wide Area Augmentation System (WAAS) Global Positioning System (GPS) units that supported the required navigational performance. Airlines for America also noted that the required performance—even for the correct WAAS GPS—was not always possible. In light of that, the organization requested that the GPS section of the ADS-B mandate be extended to 2025.

The part of the letter that most folks missed was that it only applies to the portion of the ADS-B mandate that deals with new WAAS requirements for GPS. A transponder that transmits in an ADS-B message format is required to operate above 10,000 feet by 2020.

The FAA agreed with Airlines for America and granted a temporary exemption from the GPS accuracy portion of ADS-B. The FAA has since been getting out the word that operators are still required to have an ADS-B-compliant transponder to meet the mandate. (Visit for current information on the mandates.)

Owner/operators who opt for an exemption must submit an annual request to the director of the local Flight Standards District Offices (FSDO) until the aircraft is equipped with the mandated receivers. This annual request must include a plan for an eventual upgrade to the mandated WAAS GPS and is subject to approval. For aircraft that are scheduled for major inspections at a facility where a WAAS GPS installation is available, your FSDO may deny your request. “I don’t want to upgrade,” may not be a good reason to apply for an exemption.

With manufacturers, such as Universal Avionics, Honeywell Aerospace and Rockwell Collins offering incentive programs for Flight Management Systems (FMSes) and transponder upgrades, now is the time to include new WAAS/Localizer Performance with Vertical Guidance (LPV) and ADS-B in your aircraft’s budget at your next major inspection.

Don’t bet on the unicorn.


For the most current information on the NextGen mandates visit Duncan Aviation NextGen Resource

Adrian Chene is an avionics tech rep for Duncan Aviation providing troubleshooting and technical advice to business aviation operators on avionics installation services. He specializes in custom, integrated HSD solutions. He began working in aviation in 1996.

Tags: Avionics Installation, ADS-B, NextGen


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