Evergreen Airlines in December will begin equipping the first of six Boeing 747 freighters with a Universal Avionics flight management system that boosts GPS accuracy using a variety of global satellite-based augmentation systems (SBAS).
Under the US Federal Aviation Administration programme, Evergreen will fly the avionics on its global routes for up to two years, taking data on how well the aircraft maintains desired courses or approaches using the four different augmentation systems. Evergreen is taking data on the same routes now with existing, non-SBAS FMS units as a baseline.
In the US, the wide-area augmentation system (WAAS) generates accuracy boosting correction signals that when combined with basic GPS signals in on board receivers increases position accuracy from 10m to less than 1m using a constellation of three geostationary satellites and a network of ground stations. A key benefit to having WAAS is the ability to fly vertical guidance precision (LPV) approaches, the GPS equivalent of a Category 1 instrument approach.
Globally, there are now three SBAS in operation - WAAS in the US, EGNOS in Europe and MSAS in Japan. A fourth system, GAGAN, is slated to come on line in India in 2013.
The FAA has been keen to investigate the interoperability of all the systems for airborne navigation and instrument approach applications, hence the Evergreen programme.
Evergreen plans to retrofit the existing Universal UNS-1F FMS units in the 747Fs with UNS-1Fw (WAAS-equipped) units through 2012, with the first aircraft completed by the end of January, said Scott Campbell, director of airline and military marketing for Universal. Additional 747Fs will be retrofitted every one to two months thereafter through 2012, says Campbell.
Along with crew notes on FMS performance during en route and approach segments, collected data will include FMS stored data with one second updates on metrics such as along-track and cross-track performance, estimated time of arrival, time-to-go and other data. The data will then be compared to the baseline data.
"They'll be using data recorded from systems to show demonstrated improvement in flight times and fuel burns," said Campbell, adding that a major point of the exercise is to demonstrate the economic and time saving advantages of SBAS to the airline industry.