Meet the FAA’s ADS-B Compliance Monitor—before it meets you
What happens if your Automatic Dependent Surveillance-Broadcast Out equipment is transmitting incorrect information?
You can expect to hear from the FAA’s ADS-B Compliance Monitor. Most of the time, an aircraft owner is contacted by letter, but in at least one case, the office left a note on a hangar door.
“I’ve had guys flying around with a wrong ICAO code. Have you ever tried to track down a wrong ICAO code? You don’t know who it is, but you know where he’s flying,” James Marks, an aviation safety inspector and the FAA’s ADS-B focus team lead for Flight Standards, said at a workshop during the 2015 Aircraft Electronics Association convention. The ICAO code is a discrete aircraft identification, like an N number. In one such case, Marks used the ADS-B Out GPS position information to track an unidentifiable aircraft to a specific hangar. He called the airport’s FBO and asked someone to leave a note for the pilot on the hangar door.
ADS-B, which uses satellites instead of ground-based radar to determine aircraft location, is a key technology behind the FAA’s Next Generation Air Transportation System. The FAA has mandated ADS-B Out equipage beginning January 1, 2020, for operations in most airspace where a transponder is required today.
As of March 1, 17,528 U.S. general aviation aircraft were equipped for ADS-B Out, according to the FAA, which estimates GA equipage at 11 percent to 17.5 percent of the fleet. During February 2016, 763 GA aircraft equipped with the technology. The FAA’s ADS-B equipage information comes from its Compliance Monitor system.
Marks said he has called hundreds of owners of aircraft found to be out of compliance. “Out of all of them, only one had any idea that something might be wrong,” he said.
In early 2015, more than 25 percent of ADS-B Out-equipped aircraft did not fully comply with the equipment performance requirements in FAR 91.227. Since then, that ratio has decreased, to about 20 percent.
Most problems are fairly simple configuration errors. The FAA currently is focusing on what the agency is calling “high-priority” avionics behavior, including missing or erroneous Mode 3/A squawk codes; invalid or duplicate 24-bit ICAO codes; and what’s called “egregious kinematics,” where the aircraft’s reported GPS location jumps around so much that it cannot be displayed by air traffic control—or other aircrafts’ ADS-B In systems.
Another common error is an incorrectly programmed emitter category. For example, many “Light” aircraft (here, the term light means less than 15,500 pounds) incorrectly transmit that they are “Small” aircraft (15,500 pounds to 75,000 pounds). In the world of ADS-B Out, most general aviation airplanes should be programmed as Light aircraft. Issues with air/ground determination, another parameter in your ADS-B Out broadcast, also are common—as are missing barometric or geometric altitudes.
The current emphasis of the Compliance Monitor team is on following up with aircraft operators, Alex Rodriguez, an FAA aerospace engineer, said during an FAA safety seminar in Manassas, Virginia, on February 24. “We’ve actually been involved with owners and repair stations, and owners and manufacturers, so [the aircraft owner] can correct the problem on his own aircraft.”
The ADS-B Compliance Monitor is always monitoring, Rodriguez explained. “There is no biennial check, like you have with transponders.”
He said that changes are coming to the Compliance Monitor, including the ability to request a report through a webpage. On reports from the current system, “if you don’t see any red, you’re good.” (See “Requesting a Compliance Report,” below.)
Flight Standards is starting to look at ADS-B enforcement, Rodriguez added. If the compliance monitor reports a bad ADS-B and sends a letter, and the pilot continues to fly after being advised that the equipment is noncompliant, continuing to operate the aircraft eventually will be considered “malicious,” he explained. Notification letters seen to date by AOPA identify the problem and seek a plan for correction. If an owner doesn’t understand a letter received from the FAA, AOPA recommends discussing the matter with an aviation attorney.
Enforcement may not wait until the ADS-B Out rule becomes effective on January 1, 2020. FAR 91.225(f) already requires the operation of ADS-B Out equipment, when installed, at all times—similar to FAR 91.215(c), which requires the operation of transponders, including Mode C if installed.
The FAA periodically revises the advisory circulars for ADS-B, to address the configuration errors that are being seen during installation, Rodriguez said. “As we’ve been moving on, we’re getting clarification from the field”—information from users and installers about what’s working and what’s not. The most recent iteration of AC 20-165B, Airworthiness Approval of Automatic Dependent Surveillance-Broadcast Out Systems, was issued in December 2015. An update to AC 90-114, Automatic Dependent Surveillance-Broadcast Operations, is pending, he added.
Rodriguez encouraged aircraft owners to equip with ADS-B. “ADS-B Out gives more precision on your position, because it’s using that GPS. Information comes in a lot faster. As we move forward in the FAA we want to reduce separation. This is big for the airline guys,” he said, noting that only ADS-B Out is required by the rules. “If you’re equipping with ADS-B Out in the GA community, the benefit comes from ADS-B In.”
ADS-B In provides traffic information on both the 1090-MHz Mode S Extended Squitter and 978-MHz Universal Access Transceiver frequencies, and subscription-free weather information on 978UAT only.
Email [email protected]
Requesting a compliance report
There are two types of compliance reports: one for the certification of new hardware—avionics manufacturers would use this—and a post-installation compliance report. Any aircraft owner can request the latter for his or her ADS-B Out-equipped aircraft. All that’s required is sending an email to [email protected] with a request for an ADS-B Aircraft Operation Compliance Report. Per AC 20-165B, Section 4.3.1, the email should include the aircraft registration number, location, date, and approximate local time of flight. Make the request after the test flight has taken place; no preflight coordination is required.
You’ll receive a reply, often within 24 hours, that lists the aircraft’s ADS-B performance in a number of areas. Look for any boxes that are tinted red—those indicate failure for that parameter. No red boxes? You should be good to go. If there’s a failure, talk with your avionics shop or whoever installed the hardware; depending on the problem and the specifics of the ADS-B Out installation, you might be able to fix the problem yourself.
Attached to our most recent compliance report email was an Aircraft Compliance Report User’s Guide, a comprehensive document that explains the four-page compliance report. While it could provide more detailed explanations in some areas, it’s a welcome addition that goes a long way toward helping technicians—and aircraft owners—understand the nature of any problems with an installation. —MPC
Web: See AOPA’s online ADS-B resources and ADS-B selection tool.
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