The FAA is studying the potential application of en route aircraft spacing as close as 5.6km (3nm) in some instances for operators equipped with automatic dependent surveillance broadcast (ADS-B) technology.
The agency aims to use reduced separation and its potential to decrease trip length and delays as an incentive for airlines to purchase ADS-B avionics earlier than the expected 2020 deadline for equipage.
An aircraft equipped with ADS-B can broadcast its GPS-based position to ground stations and other aircraft with similar tools.
Currently the minimum separation standard for equipped aircraft is 9.3km, but this year the agency received $6.8 million from the US Congress to evaluate spacing that is between 5.5km and 9.3km.
FAA surveillance and broadcast services director Vincent Capezzuto says the agency is developing safety criteria to govern the reduced separation for the applicable airspace.
FAA expects to issue its final rule in April 2010 to mandate ADS-B equipage by 2020. The agency published a technical standard order (TSO) for ADS-B avionics units earlier this month.
The FAA's Surveillance and Broadcast Services Office, which is tasked with deploying ADS-B across the national airspace, plans to begin rolling out incentives for equipped operators between 2010 and 2013 after the final ADS-B rule is published, Capezzuto says.