By having more precise and timely position information, the FAA says it will be able to reduce aircraft-to-aircraft separation standards by some amount from today's values of 5.6km (3nm) in terminal airspace and 9.2km in the enroute environment, thereby boosting system capacity.

To do that, onboard equipment must provide output to the ground every 1s that includes horizontal position with an accuracy of 30m (98ft), vertical position accurate to 45m, and velocity information good to 10m/s. Pilots will be required to monitor equipment to ensure the equipment is computing and broadcasting correctly.

Source: Flight International