IFR Checkride Guide
Chair flying / DME Arc

DME Arc

Intercept and maintain a DME arc — turn-10-twist-10 discipline, arc-to-radial lead, and staying within 1 NM of the arc.

Guided rehearsal is PremiumACS V.A — Intercepting and Tracking Navigational Systems and DME Arcs

Setup

  1. Tune and IDENTIFY the VOR/DME; confirm DME distance alive
  2. 100 KIAS, brief the arc — direction, radius, lead radial to final
  3. Compute the intercept lead: at 90–100 kt groundspeed, lead the arc by about 0.5 NM

Execution

  1. At lead distance, turn ~90° from the radial to put the station off your wingtip“Lead — turn”
  2. Turn 10, twist 10: every 10° of arc, turn 10° and re-center the needle
    With an RMI or bearing pointer, keep the needle on the wingtip reference (slightly ahead corrects inside drift). With an HSI/OBS, re-twist the course every 10° of radial change.
  3. Inside the arc? Distance decreasing — shallow out. Outside? Turn toward the station
    Correct with 10–20° cuts; small early corrections beat big late ones.
  4. Maintain arc within 1 NM, altitude ±100 ft, airspeed ±10 kt
  5. Approaching the lead radial, twist the final course and turn to intercept

Recovery

  1. Established on the inbound course — CDI within ¾ scale
  2. Continue the procedure or resume navigation as cleared

ACS tolerances

  • Arc within 1 NM
  • Altitude ±100 ft
  • Airspeed ±10 kt
  • Headings ±5° when tracking

Common errors

  • No intercept lead — blowing through the arc
  • Chasing the DME readout with large heading swings
  • Forgetting to twist the OBS around the arc, losing orientation
  • Missing the lead radial for the final course turn