A new FAA order — specifically JO 7110.65, paragraph 5-7-1 — may leave some pilots wondering if they’ve misunderstood ATC’s instructions when they’re asked to fly airspeeds such as 255 or 195 knots, speeds all calculated in 5-knot increments. At or above FL 240, crews can expect Mach number instructions in 0.01 increments for turbojet aircraft with Mach meters.
The change, beginning August 29, is part of the agency’s effort to create more time-based ATC separation standards, as more and more distance based standards disappear, under the evolving Performance Based Navigation (PBN) standards of NextGen. Pilots may notice use of the new speed restrictions results in slightly longer vectors to the final approach, according to the chairman of the NBAA’s ATC working group Rich Boll. But he added that the ability to more precisely tune an aircraft’s final approach speed should also lead to more direct routings that reduce overall flight time.
Boll said while pilots may only encounter the new speed changes during arrivals for the present, they should expect the use of the 5-knot separation standards farther and farther out from hub cities as the use of NextGen arrival procedures expands.
