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Conducting a Stabilized Non-Precision
Approach using CDFA
(Continuous Descent Final Approach) by Ed Verville
Why do the airlines, 135 operators and the FAA use and recommend CDFA? Controlled Flight Into Terrain (CFIT) is one of the leading causes of fatal accidents, and an un-stabi- lized approach can lead to CFIT. Based on this, all ma- jor airlines and most Part 135 On Demand Operators use Continuous Descent Final Approach (CDFA) procedures for non-precision approaches rather than the old dive-and-drive method. It makes them safer. So, why not learn from this and do it in your privately flown aircraft as well?
This isn’t something new, I was taught CDFA proce- dures at my first airline more than twenty years ago, but we still see accidents that might have been avoided us- ing CDFA best practices. If you need just a little more motivation, the FAA recommends adopting CDFA as standard operating procedures for ALL operators in their Advisory Circular AC 120-108A.
In just one example, on August 14, 2013, an Airbus A300 was conducting a localizer-only approach (the glide slope was out of service) to Runway 18 at Birmingham, Alabama
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(KBHM). The airline’s normal procedure is to use CDFA, but on this day, the crew mismanaged the final approach descent, set the vertical descent rate to 1500 fpm, switch- ing to the dive-and-drive technique without briefing the change, and flew the airplane into the ground. (See NTSB Report AAR 1402 and the “video companion” for details).
A CDFA approach path might have more appropriately allowed the pilots of this aircraft to fly a continuous descent to minimums and then continue to a landing if the runway environment was in sight or execute a go-around and fly the missed approach needed instead of having a descent, a level-off, then re-establishing a descent if the runway environment were seen.
The main point is that a CDFA approach increases the probability of a stabilized approach. The FAA states that a “CDFA is a technique for flying the final approach segment of a non-precision approach as a continuous descent. The technique is consistent with stabilized approach procedures and has no level-off”.