The US FAA is concerned over a high number of incorrect flight plan requests for reduced vertical separation (RVSM) operations in US airspace.
According to an Information for Operators note issued on 18 January, the FAA found 35 cases of incorrectly submitted instrument flight plans with respect to RVSM operations in the first 15 days of November.
"These events indicate that not only are 'non-RVSM' aircraft being filed as RVSM authorized, but also, authorized aircraft unable to conduct RVSM due to equipment malfunctions are being incorrectly filed as RVSM authorized," the FAA said.
In general, aircraft flying above 29,000ft must have specially calibrated altimetry equipment to allow for adequate clearance with other aircraft flying at 1,000ft intervals vertically. Pilots too must be trained in RVSM operations, which include mandatory use of autopilots in RVSM airspace and actions to be taken if failures occur.
The agency notes that the air traffic control automation system does not alert controllers when non-RVSM aircraft file to use RVSM airspace.
The FAA is recommending that pilots, dispatchers, flight followers and other industry officials become "knowledgeable of flight planning requirements" related to RVSM, as well as what malfunctions disqualify an aircraft from RVSM operations.
While not stated, a key underlying concern is that aircraft not properly equipped for, or pilots not adequately trained for, RVSM operations could pose a collision risk to other aircraft due to the close vertical proximity and high speeds in cruise flight in RVSM airspace.
"Pilots should remember that regardless of who files the flight plan, the [pilot in command] is responsible for operating [within the rules], including correct flight plan filing," said the FAA.