GRAHAM WARWICK / WASHINGTON DC
Pocket by pocket, the USA is implementing automatic dependent surveillance - broadcast (ADS-B) - where it can find partners to share the cost of deploying the capability. The next pocket after Alaska will be the East Coast, from Florida to New Jersey. This could be followed by the Gulf of Mexico.
ADS-B is operational in western Alaska, providing radar-like surveillance of 200 general aviation aircraft around Bethel equipped by the Federal Aviation Administration under Phase 1 of its Capstone programme. Another 200 aircraft operating in south-eastern Alaska, around Juno, are to be equipped over the next year under Capstone Phase 2.
In Phase 1, ADS-B is used for surveillance and flight following. Phase 2 will add separation services. Capstone uses the UAT datalink for ADS-B, and equipment supplier UPS Aviation Technologies is expected to certificate the standards-compliant version of its transceiver by early next year, for installation in Phase 2 and retrofit into Phase 1 aircraft.
Capstone is the basis of plans to implement ADS-B elsewhere in the USA. Site surveys have begun for installation of the 20-25 ground stations required to provide ADS-B coverage down to 1,000ft (300m) along the East Coast. The interim infrastructure is aimed at general aviation users, and will not feed air traffic control. Instead the UAT link will provide traffic and weather data.
The first ground station will be installed by December, says the FAA, and the rest by the end of 2006. Partners include Embry-Riddle Aeronautical University, which will equip 70 Daytona Beach, Florida-based training aircraft with ADS-B, primarily to prevent mid-air collisions. The states of Maryland and North Carolina will pay for ground stations and equip their aircraft.
The ground stations will be prototypes and the FAA is due to decide in 2006 on whether to begin deploying production ADS-B equipment. Embry-Riddle also plans to equip another 40 aircraft at its Prescott, Arizona, campus with ADS-B. The FAA will install three ground stations and provide traffic and weather broadcasts.
Most ADS-B activity in the USA is centred on general aviation, but not all. UPS Airlines is equipping 103 Boeing 757 and 767 freighters with ADS-B avionics produced by its Aviation Technologies subsidiary. This uses Mode S as the datalink and includes a cockpit display of traffic information (CDTI) combining ADS-B and the traffic collision avoidance system. The FAA has installed a ground station at the package carrier's Louisville, Kentucky, hub.
Initially, ADS-B will help pilots acquire other aircraft visually during the approach, and UPS will equip its Airbus freighters with "ADS-B out" so that 757s and 767s can see them. The next step, set for early next year, is integration with the air traffic control system at Louisville, so that controllers can see which aircraft are ADS-B equipped.
This will allow CDTI-enhanced flight rules (CEFR), under which pilots will be able to continue a visual approach even if they lose sight of the other aircraft, against a background of city lights or when descending through a cloud layer, as long as it is visible on the cockpit display. UPS is also looking at using ADS-B to manage arrival spacing by allowing aircraft to match speeds using CDTI.
The planned ADS-B trial in the Gulf of Mexico, where there is a gap in both radar and communications coverage, will involve four ground stations on shore and three on deep-water rigs. UPS and Continental Airlines will participate.
Under FAA contract, meanwhile, Boeing will test the feasibility of using commercial communications satellites for ADS-B over the Gulf of Mexico later this year, using its Connexion One testbed.
Source: Flight International
