From The FAA: NextGen

ADS-B is available on two bands: 1,090 MHz is mandated for all aircraft operating in Class A airspace above 18,000 feet, while 978 MHz is available in all other ADS-B controlled airspace (Classes B, C, and E above 10,000 feet); 978 MHz is the UAT, which is a wide band multipurpose data link operating on a single channel. It is being offered to the GA folks to curb the oversaturation of 1,090 MHz. One incentive for someone going to UAT is the Flight Information Services-Broadcast (FIS-B); it will provide weather, NOTAM messages, etc. FIS-B is available only to UAT-equipped aircraft.

The avionics technicians will need to set up and test each aircraft’s ADS-B system; every ADS-B equipped aircraft will be assigned a 24-bit address by the International Civil Aviation Organization (ICAO). This address will be used by ground operations to identify the specific aircraft; the address may either be programmed at the avionics bench in the shop or at the rack while installed on the aircraft.

As with a transponder, ADS-B will be used to locate and track an aircraft. However while the transponder enables ground to interpret bearing, range, and altitude via primary and secondary radar signals, ADS-B translates information from multiple sources, e.g. GPS, ADC, and the FMC. The ADS-B then transmits the multiple interrogations it receives into a solitary strand of “single-language” data to the ground.

Maintenance aspects

Aircraft technicians will see an increase in available manufacturers’ training as industry catches up. It’s still early on for this article to specify what type(s) of training will be available, so let’s look at what the needs of some systems should be. Since the ADS-B inputs are dependent on each other, the maintenance will not be limited to component replacement. Returning the ADS-B system to service is a total system check; if the system is disturbed and/or the replaced component(s) have a dedicated input to the ADS-B, full system testing of the ADS-B will need to be accomplished as well as the source systems, e.g. TCAS, GPS, etc. These system tests resemble the maintenance requirements for returning a CAT II/CAT III lower landing minima-equipped aircraft to service; this knowledge requires initial systems training and requalification training every year.

How will the AMT modify an aircraft? The manufacturers are still improving the technology; on most general aviation (GA) aircraft (and some commercial aircraft) the modifications include replacing or upgrading transponders and/or antennas.

According to the aircraft and the systems presently in place, rewiring is necessary to upgrade the aircraft. Initially, installation approvals will be through type certificate (TC), amended TC, and supplemental type certificates (STC) and not through local field approvals; the STC process usually works through the FAA Aircraft Certification Offices. There are already several ADS-B STC installations approved for helicopter, turboprop, and commercial jet aircraft; these include fitting of antennas, trays, wiring, transponders, and cockpit traffic displays.

According to Advisory Circular 120-86, “ADS-B link systems will consist of a combination of the 1090 Extended Squitter (ES) link for air carrier and private/commercial operators of high performance aircraft, and UAT, to be used primarily by GA.”

Delays

Now not everyone will jump into NextGen with both feet; several factors have dictated the industry’s inclination to have their equipment upgraded. The recession has hit everyone hard, whether they’re GA, air taxi, or scheduled service, with some hit harder than others; the money is just not there at this time. Although the FAA target date is 2020 for full NextGen spool-up, some operators and pilots will delay their entry into NextGen, determined not to buy into present day systems that could be antiquated by 2020. And then there are some who will see how the economy does to determine if they’ll even be around by 2020. Whatever the reason, 10 years is a long time for the world to change and technology to improve.

Go to www.faa.gov for NextGen information and links. To view the new rules, go to: http://edocket.access.gpo.gov/2010/pdf/2010-12645.pdf. AMT

Stephen Carbone is an aviation industry veteran of 28 years. He works at the Boston regional office in the Flight Standards Airworthiness Technical Branch. He holds a master’s degree in aviation safety systems.