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constant airspeed or configuration again, while it reiterates: “A pilot is f lying a stabilized approach when he/she established and maintains a constant angle glidepath toward a predetermined point on the landing runway,” with the bold font emphasis being the FAA’s. It goes mainly into the need for a three-degree glidepath and the way to determine vertical speed for that angle of descent and others. The FAA does not suggest when it is appropriate to enter this stabilized condition, but does say, “the approach is more at risk of being unstable when closer to the runway (i.e. 500 feet to 1000 feet height above touchdown (HAT)).”
NBAA’s guidance on flying a sta- bilized approach is exclusively about glide angle (figure 1). NBAA says “the aircraft should meet stabilized ap- proach criteria no lower than 1000’ (IMC) or 500’ (VMC). It notes that “final f lap configuration may be de- layed at pilot’s discretion” even below
that height, and that this is done not for landing accuracy or control but to “enhance noise abatement.”
In the slot
Coming in on a long straight-in, on that stabilized glide angle, it may be more important to be on a trend to a runway threshold speed and con- figuration. To do this, I self-evaluate whether I am “in the slot.” By this, I mean I continually ask myself, from about 500 AGL to the beginning of the landing flare, if I am:
• On speed, or more likely on a trend toward the airplane’s recom- mended 50-foot short final speed (on a three-degree glidepath toward a point 1000 feet from the runway threshold, I’ll be at about 50 HAT as you cross the runway threshold);
• On glidepath to the touchdown zone;
• In configuration, perhaps with full flaps to go, and;
• In alignment with the runway centerline, with zero sideways drift.
The further out you begin the final approach, the sooner you can make that evaluation and the more time you have to make corrections. Be- low 500 AGL (about the height where you’d turn final f lying a standard traffic pattern), if you’re not in the slot, it’s time to go around. Don’t wait until you’re in the flare to go around.
Meeting the “in the slot” criteria also helps you alight at the proper place without excessive energy. That makes it far less likely you’ll go off the far end of the runway. Runway overruns are usually the outcome when an unstabilized airplane (i.e., one not in the slot crossing the thresh- old) touches down long beyond the touchdown zone with too much speed (energy) to stop on the remaining sur- face. A corollary is a pilot who waits too long to make a go-around decision and cannot clear obstacles when he/ she finally powers up to climb.
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