DME arcs

Flying a constant distance around a station, and knowing when a lead radial is charted, on the real Hilo VOR/DME 26.

14 min read · Charts and procedures

After this lesson you can

  • Explain why a DME arc is classified as an approach segment rather than a feeder route.
  • Read a charted DME arc and its NoPT label, and state when a lead radial is charted.
  • Compare an arc-based initial segment against a HILPT-based initial segment serving the same runway.
  • Read the charted radius of an arc off the plan view and fly it with the toward-away correction technique.

A DME arc is one more way of solving the same problem a procedure turn or a HILPT solves: getting an arriving aircraft from wherever it starts onto the correct inbound alignment for the final approach course. Instead of a straight leg and a reversing turn, the aircraft flies a curved path holding a constant distance from a VOR or VORTAC, tracing part of a circle until it reaches the point where the final course begins.

This lesson reads the VOR/DME or TACAN RWY 26 approach into Hilo International (PHTO), which uses an 11 DME arc as its initial segment, and compares it directly against the ILS or LOC RWY 26 approach at the same airport, which instead uses a HILPT at a dual-purpose fix. Same runway, two different answers to the same geometry problem.

The rest of this lesson

  1. 1.An arc is an approach segment, not a feeder route
  2. 2.The Hilo 11 DME arc
  3. 3.Flying the arc: watching distance, not just heading
  4. 4.The same airport, a different answer: HILPT at CEKOB

These 4 sections, their figures, the checks along the way and the end-of-lesson quiz come with the IFR track. Paid once, yours for good.

See what the IFR track costsEvery module 1 is free to read, no account, no card.

Key terms

Try to recall each definition before turning the card.