Chris Kjelgaard/LOUISVILLE

The US Federal Aviation Administration (FAA) and US cargo carriers are to launch the third operational evaluation (OpEval 3) of automatic dependent surveillance broadcast (ADS-B) in May, following encouraging controller and pilot feedback from the OpEval 2 trials in Louisville, Kentucky, late last month.

To be hosted by Federal Express in Memphis, Tennessee, OpEval 3 will give the FAA its first opportunity to trial the integrated network of technologies involved in its Safe Flight 21 initiative. Safe Flight 21 is testing emerging technologies designed to improve flight safety while increasing capacity. ADS-B, which forms the backbone of the programme, provides the cockpit crew with the same information as the controller so that traffic can be managed more efficiently.

OpEval 3 could also see adoption of the definitive datalink standard for ADS-B. Safe Flight21 programme head Jim McDaniels says the team is "nominally" planning to decide "in mid-2001" which of three standards - Mode S, Universal Access Transceiver and VDL Mode 4 - to adopt.

US industry sources believe that Mode S is the favoured candidate. The European VDL Mode 4 was not evaluated in the trials, while ADS-B pioneer United Parcel Service has certificated initial ADS-B functionality for its Boeing 727s using Mode S datalinking.

Safe Flight 21 team member Paul Fontaine says that, where OpEval 2 focused on four new ADS-B applications - approach spacing, departure spacing and clearance, runway occupation alerting and airport surface situational awareness - OpEval 3 will involve airport situational awareness and runway incursion alerting.

OpEval 3 will also trial uplinking to flightdecks of traffic information services-broadcast (TIS-B), position data concerning aircraft and airport vehicles not equipped with ADS-B. The TIS-B data will be generated by passive/active Mode S interrogation of targets by airport-sited multilateration units, and by high-update rate ASDE-X radars developed for the FAA's airport surface awareness effort.

OpEval 3 will also see airport surface moving maps upgraded to include an alerting function, equipping "large numbers" of ground vehicles, and, for controllers, new colour displays with target data tags.

Source: Flight International