Gettin’ Down

Tuesday, May 17, 2022 at 03:17 PM ET

Verified

Key Takeaways:

Pilots may descend from their last assigned altitude only after receiving "cleared for the approach" AND being established on a published route (such as an approach segment, feeder route, or Terminal Arrival Area) where a lower altitude is charted, provided no explicit altitude instruction overrides this. Lateral instructions alone (e.g., "direct to a fix") do not authorize descent.
The term "published route" is broad, including not just segments depicted on approach charts but also en-route airways, feeder routes, and especially Terminal Arrival Areas (TAAs), which allow descent to their charted altitudes once the approach clearance is received and the aircraft is established within the TAA.
Understanding these specific descent rules is critical for safe and efficient operations, particularly with modern RNAV procedures and TAAs, as they enable earlier approach clearances and allow pilots to leverage avionics for reduced workload.

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Having departed from Pompano Beach, Florida, we’re going to Greensboro, North Carolina, to visit family. The winds at Greensboro’s Piedmont-Triad International (KGSO) are northerly and the ATIS says we should expect the ILS 5R approach. All else being equal, we prefer GPS and LPV to localizer and glideslope. We ask for the RNAV approach to the same runway and the friendly KGSO controllers are happy to accommodate. Cruising along at an assigned altitude of 6000 feet MSL we hear, “Two five miles from COSIS. Direct COSIS. Cleared RNAV Five Right approach.” When may (should) we descend and to what altitude?

Two interrelated principles give us the answer. First, hearing “cleared for the approach,” permits us to descend from our last assigned altitude as soon as we are on a published route (unless we are assigned an altitude to maintain). Second, nothing but the words “cleared for the approach” allows us to descend on our own initiative from our last assigned altitude. These are simple statements that can easily be misunderstood, leading to possible trouble.