THE US FAA has announced that air traffic controllers in Houston, Texas, have started using ADS-B for flights over the Gulf of Mexico. An ADS-B-equipped aircraft determines its own position using a global navigation satellite system and periodically broadcasts this position and other relevant information to potential ground stations and other aircraft with ADS-B equipment. It can be used with several different data-link technologies and is being developed as part of the USA’s Next Generation Air Transportation System. FAA Administrator Randy Babbit called it a “significant, early step toward the future,” for an area that has previously lacked full radar coverage. Controllers previously “had to rely on an aircraft’s estimated or reported, not actual, position,” the FAA said. Commercial aircraft at high altitude had previously been kept as much as 120nm apart to ensure safety, but ADS-B will allow the separation to be reduced to 5nm.