I'm here at the FAA's Shared Vision for Safety Conference in San Diego.  Yesterday I heard a shocking statistic:


Especially dangerous are night approaches to runways without a PAPI or VASI.  It leads me to write this article on conducting non-precision approaches.  If just one of you reads this article and uses this method from my book, IFR Checkride Reviewer, then I will have probably saved a life.  If you're an instructor, then I urge you to teach visual descent points and stabilized approaches.

Probably 15 years ago, we (flight instructor community) realized that dive and drive approaches were probably not the safest way to go.  The dive and drive approach contemplated getting down to the Minimum Descent Altitude (MDA) as quickly as possible so that as the runway appears, you'll be low enough to land.  The only problem with that theory is natural and man-made obstructions along the path.   Approaches are designed so that you would be able to clear such approaches even if you're steeper than the typical three degree glide path to the runway.

A recent development (2000) is the CANPA (Constant Angle Non-Precision Approach) profile, sometimes known as a CARD approach. The goal is to fly a constant angle approach even if a glide slope or visual slope indicator such as a VASI or PAPI is unavailable. It looks like an ILS and involves making a stabilized constant angle descent rather than a quick dive to the MDA.  Upon reaching the MDA, the pilot would fly level until the runway environment is in sight or upon reaching the missed approach point.  Notice that in the same approach the airplane comfortably clears the tall tower on the CANPA profile.

Benefits of the CANPA profile include:

1. This reduces pilot workload and provides for enhanced situational awareness.
2. The technique is similar to an ILS and allows for a constant descent rate and power setting.
3. The technique provides the pilot with the time to acquire visual cues for landing.
4. It's fuel efficient!
5. Reduced noise on the final approach path.
6. Terrain clearance!
   

Notice in the profile above.  The aircraft still respects the VDP or step-down fix.  CANPA just allows you to descend to the MDA or final step-down fix in a manner that you see the runway and you're in a position to continue the approach with minimal adjustments to the flight path.  MDA or step-down fix altitudes must be respected and the missed approach still occurs at the missed approach point.

How this stabilized approach descent rate begins depends on whether the approach has a Final Approach Fix (FAF). 

Approaches with an FAF	Approaches without an FAF
The FAF starts the descent.	When an FAF is not provided, you'll typically begin the descent when you are "10-10-Clear" -- meaning when you are within 10 miles from the runway, within 10 degrees of the approach course and cleared for the approach.  From this point, you would descend towards the runway at a 3 degree glidepath. You will need to know the distance to the runway to calculate that.

The distance from FAF to the MAP can be determined by:
·  DME
·  Navaid located at the FAF
·  GPS
·  ATC Radar