Watch your Step(down)

Most pilots I know are lazy. Writing as one who has spent most of his career flying airplanes, thats meant to be a compliment. The lazy pilot tends to accomplish the least work necessary in order to achieve the intended goal. This usually improves workload management and provides a greater reserve of attention. However, sometimes laziness can get you into trouble, such as in determining when to intercept and track a glidepath. …

Editorial Staff

Thursday, July 31, 2014 at 12:00 AM ET

Verified

Key Takeaways:

Pilots often incorrectly intercept the glidepath early on instrument approaches, assuming it ensures obstacle clearance and compliance with stepdown fixes before the Precise Final Approach Fix (PFAF).
However, obstacle clearance along the glidepath is only guaranteed from the PFAF to the runway; early interception can result in flying above or below intermediate segment stepdown fix altitudes, or create issues due to altimetry errors.
ATC instructions to be "established" refer to the final approach course, not necessarily the glidepath, meaning pilots must adhere to published stepdown altitudes and not descend on the glidepath prematurely.
The FAA explicitly cautions pilots against early glidepath interception, stating it does not guarantee compliance with published stepdown fix altitudes outside the final approach segment.

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Most pilots I know are lazy. Writing as one who has spent most of his career flying airplanes, that’s meant to be a compliment. The lazy pilot tends to accomplish the least work necessary in order to achieve the intended goal. This usually improves workload management and provides a greater reserve of attention. However, sometimes laziness can get you into trouble, such as in determining when to intercept and track a glidepath.

When cleared for an approach with vertical guidance (ILS, LPV, etc.), it’s common for pilots to stay level until they intercept the glidepath, with the mistaken belief that the glidepath will cross at or above any stepdown fixes prior to the FAF. The alternative would be to dive-and-drive all the way to the FAF, and only then to intercept the glidepath. This method seems like it would be extra work—the bane of the lazy pilot—not to mention pointless, since you’ll cross the FAF at the same altitude using both methods.