On the evening of Aug. 27, in cooperation with Boeing, the FAA and San Francisco International Airport, we used a Boeing 737 to fly a series of specially designed NextGen approach procedures to demonstrate the operational and environmental benefits of the Ground Based Augmentation System (GBAS), a satellite-based precision landing system that may eventually replace legacy instrument landing systems (ILSs) installed at airports around the world.


In use for decades, an ILS has several limitations that a GBAS seeks to remedy. An ILS requires two fixed ground antennas and produces a single, non-variable approach path. Taxiing aircraft, buildings, terrain, and snow and ice can interfere with ILS signals, making them unusable or requiring air traffic control to increase the spacing between landing aircraft, which can result in delays. GBAS, however, can allow for tighter aircraft spacing, more approach options, steeper approach paths and greater visibility in bad weather because of its reliance on satellite positioning. Ultimately, these advantages could lead to fewer delays and precision landing in unfavorable weather, as well as increased fuel efficiency, lower emissions and a reduction in noise due to the higher glide paths. It's also easier to install and maintain.



According to Industry Affairs Director Glenn Morse, we chose SFO as the test location for a variety of reasons, including weather issues in the Bay Area and the challenging runway layout.


"When weather is poor, the airport's arrival capacity is cut almost in half, causing delays and cancellations," said Glenn. "The procedures we demonstrated last week, if approved, may allow us to run our operation on poor weather days more like we do on good weather days."


We have been a proponent of GBAS technology since the late 1990s. Currently, GBAS is installed at two of our hubs -- IAH and EWR -- and we hope to add the system at SFO and our other hubs in the future. Our Boeing 787, Airbus A350 and many of our newer 737 aircraft that have a GPS landing system (GLS) installed are capable of using GBAS.

"GBAS is the most precise navigation aid ever developed," said Chief Technical Pilot Ron Renk. "Our near-term goal is to move it from its current Category I certification to Category III, meaning aircraft can rely on it for automated landings, as they now do with ILS. We also hope to apply lessons learned from our demonstration flight at SFO to develop new GLS approaches for IAH and EWR that leverage the technology."