IFR Airport Basics

Recently, a reader asked about a puzzling approach at Chatham, MA (KCQX). The RNAV (GPS)-B is perfectly aligned with Runway 24 and the descent angle is a routine 3.05 degrees, yet it has only circling minimums. Approaches most often just have circling minimums if the alignment to the runway exceeds 30 degrees (for most procedure types) or the descent angle is greater than 3.77 degrees (for Category C and below). So, whats up at Chatham?

Editorial Staff

Friday, January 08, 2016 at 12:00 AM ET

Verified

Key Takeaways:

Airport infrastructure details, such as runway markings, weather reporting capabilities, and navigation facility monitoring, critically determine the available instrument approach minimums and overall utility of a procedure.
Specific infrastructure limitations, like basic visual runway markings (as seen at Chatham, MA), can restrict otherwise aligned approaches to circling-only minimums, while weather reporting affects commercial operations and alternate planning eligibility.
Pilots must pay close attention to NOTAMs regarding airport infrastructure outages, as these failures can directly impact instrument approach procedures, their minimums, and alternate planning considerations.

See a mistake? Contact us.

This procedure has only circling minimums because of the runway markings, of all things. The runway has basic, visual markings; straight-in minimums require at least non-precision instrument runway markings. This little detail isn’t found on the chart or in the Airport/Facility Directory, but can be found in online sources, such as Airnav.com, which are based on FAA airport survey data.