The FAA has extended for a second year an operational evaluation of pilot initiated climbs and descents using in-trail procedures (ITP) in Pacific Ocean airspace. The trial involves 12 United Airlines Boeing 747-400s flying between the U.S. West Coast and Australia and New Zealand. Having extended the evaluation to Aug. 15, 2013, the agency said that it is also holding “exploratory conversations” with ANA and Japan Airlines to include some of their aircraft in the process.

The use of ITP enables the pilots of two properly-equipped aircraft flying on the same track–one leading, one trailing–to maneuver to more optimal flight levels as desired, with lesser spacing between the aircraft than controllers would allow using “procedural” separation standards. The expected benefits of ITP are safer, more efficient operations with reduced fuel burn and emissions.

Procedural separations are necessary in oceanic airspace outside the coverage of radar, and are based on pilots making hourly position reports to controllers by radio. ITP maneuvers are made possible by GPS-based automatic dependent surveillance-broadcast [ADS-B] position reports, which can be seen by both the pilots and controllers. Aircraft must be equipped with an ADS-B transceiver and have the capability to display nearby air traffic on the flight deck. The pilot of either a leading or a trailing aircraft can request an altitude change from air traffic controllers based on the position of the other, non-maneuvering, or “reference,” aircraft. Before approving the change, “the controller verifies that the ITP and reference aircraft are same direction traffic and that the maximum closing Mach differential is less than or equal to a Mach number of 0.06,” according to the FAA.

The FAA established agreements with United Airlines and avionics manufacturer Honeywell to install and certify the necessary equipment on 12 United 747s. The companies chose Goodrich, now part of UTC Aerospace Systems, to supply the electronic flight bags used on the flight deck to display ADS-B position reports from nearby aircraft.

In a presentation to the Informal Pacific ATC Coordinating Group in late October, the FAA said that only 81 pilots of the 598 expected have been trained in ITP procedures—or about 14 percent—contributing to a low number of ITP clearance requests. According to an industry source, there is a provision for ITP training contained in the new labor contract that United and former Continental pilots will vote on in mid-December. This could not be confirmed at AIN's press time.