An airport ground vehicle transmitter developed by ITT Exelis and avionics manufacturer FreeFlight Systems is the first such device certified to a new standard by the U.S. Federal Aviation Administration (FAA). Ground vehicles fitted with the device can be monitored by air traffic controllers, improving “situational awareness” and safety at busy airports. The vehicle movement area transmitter (V-MAT) continuously reports the position of a ground vehicle through automatic dependent surveillance-broadcast (ADS-B) OUT transmissions.
ITT Exelis (Chalet C4) offers the V-MAT, which is based on FreeFlight Systems’ RANGR-G transponder, as part of its “Symphony” suite of airport operations management applications. The Herndon, Virginia-based company implemented the first V-MAT devices at Logan International Airport in Boston in collaboration with the FAA and the Massachusetts Port Authority (Massport). As of May, there were 37 devices installed on ground vehicles at Logan airport and 40 sold to the St. Louis airport authority, which operates Lambert-St. Louis International Airport.
ITT Exelis said it has submitted proposals to airport authorities in Atlanta, Chicago, Denver and Milwaukee to sell the V-MAT units manufactured by FreeFlight Systems, of Waco, Texas. ITT Exelis is the system vendor, and provides installation, implementation, testing and support of the devices under contract with an airport. ADS-B ground vehicle transmissions on the 978 MHz Universal Access Transceiver (UAT) frequency are fused with the Airport Surface Detection Equipment, Model X (ASDE-X) multi-sensor surveillance system used at 35 major U.S. airports. Nine other airports receiving surface surveillance capability upgrades will also be able to integrate ground vehicle transmitters.
Firefighting trucks, snow removal equipment and service vehicles fitted with V-MAT units transmit identification and position data once per second. The information is processed through the ADS-B ground infrastructure and displayed on controller displays as well as on the cockpit displays of appropriately equipped aircraft. Through the ITT Exelis “Symphony MobileVue” application, the surveillance data is available to ground vehicle operators on Apple and Android mobile devices.
According to the FAA Air Traffic Organization’s ATO News, ground vehicle trackers at Boston Logan International contributed to safe operations during the “Nemo” snowstorm in February this year. “During Nemo, we had a ‘white-out’ with lots of blowing and drifting,” Vincent Cardillo, Logan airport’s deputy director of aviation operations, told the publication. “Vehicles with ADS-B could tell what taxiway they were on, whether they were on the left or the right side of the taxiway, and even how close they were to the hold line.” The vehicle drivers managed to return safely to their garages when the snowstorm made it too dangerous to operate.
The V-MAT device complies with FAA Advisory Circular (AC) 150/5220-26, “Airport Ground Vehicle ADS-B Out Squitter Equipment,” which was originally issued in November 2011 and updated last September. The AC provides guidance on the development, installation, testing, approval and maintenance of ADS-B Out squitter units for ground vehicles. Airports can refer to the document to acquire FAA-authorized tracking devices.
“Every year, there are incidents and accidents involving aircraft and vehicles at airports that have potentially serious consequences. Many of these events occur in periods of reduced visibility, which can result in a loss of situational awareness for flight crews and air traffic controllers,” the FAA states in the AC. “…The inclusion of airport vehicles into the surface surveillance picture gives air traffic controllers and operators one more way to identify traffic issues, understand the most efficient way to proceed on the airport surface, and avoid incursions.”
While ground vehicle transmitters can operate on either of the two designated ADS-B data links–978 MHz UAT or 1090 MHz Extended Squitter (ES)–the FAA in the AC says it “strongly prefers” 978 MHz due to 1090 spectrum congestion. It notes that existing terminal radar secondary surveillance systems, many aircraft transponders and several other systems use the 1090 MHz frequency. The agency also limits the number of ground vehicle transmitters to 200 per airport out of the same concern over frequency saturation. Transmissions are limited to aircraft runway and taxiway movement areas, or what the FAA calls “high-energy pavement,” so that controllers are not overloaded with signals.
While the V-MAT is the first ground vehicle tracking device certified to the new FAA standard, it is not the first such device. Saab Sensis started offering a “VeeLo” tracking device in 2003, and according to CEO Marc Viggiano the company sold thousands of those units. But VeeLo units transmit using the mode-S 1090ES message format and frequency. In AC 150/5220-26, the FAA favors the use of UAT transmitters.
“We actually designed and built several years ago a UAT version of VeeLo,” Viggiano said. “But we have not turned it into a product yet and offered it for sale because frankly it hasn’t passed the business case for us because UAT just isn’t used outside the U.S. As a businessman I can’t say that there’s a solid business case yet; that may change at some point.”
