IFR Fix: Surprise! DME required
Nobody wept when nondirectional beacons (NDBs) began disappearing from the IFR “architecture.” If all the decommissioned NDBs were buried in one mass grave, I can think of several pilots who would dance on that tomb of technological torment.
NDB approaches didn’t bother me, after a customarily awkward introduction. But teaching them to unenthusiastic instrument-rating aspirants, long an unavoidable exercise, was like taking a sick cat to the vet (first you must catch the cat, then you must listen to the wailing all the way to the animal hospital).
DME—distance measuring equipment—elicited the opposite reaction from instrument trainees. DME reduces approach workload and was the closest thing you got to a free ride on a nonprecision approach. Flying a VOR/DME approach, not a basic VOR approach, you didn’t have to engage in the sketchy business of timing from a final approach fix to a missed-approach point based on groundspeed guessing. To identify an airway intersection, forget waiting for a crossing radial to show up; just let DME count it down. With DME on board, those round-gauge or steam-gauge cockpits were the lap of luxury, or so we imagined, not being able to see the future.
The absence of DME from an approach’s title usually meant you just went back to doing things the hard way. But proceed with caution because that’s not always the case now.
Under an international naming convention, which the FAA adopted several years ago, only the “navigation system used to provide lateral navigation guidance within the final approach segment” is to be published in procedure titles. In plain English, DME won’t appear in procedure titles even if DME is required to execute the final approach because DME doesn’t provide lateral guidance. This procedure chart, which expires on Sept. 13, 2018, is an example.
The FAA didn’t really advertise the change, which will gradually affect more than 800 procedures and should appear in the Aeronautical Information Manual and the Instrument Pilot Handbook in 2019.
So prevent a rude surprise in flight by checking the approach’s notes and equipment requirements—not just its title—to confirm you are equipped to fly the procedure.
Dan Namowitz
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