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Are You Flying Non-Precision Approaches The Way The FAA Wants You To?

Boldmethod

Are you flying non-precision approaches the way the FAA wants you to? Here's how they recommend you fly them to give yourself the greatest chance of landing safely...

Unstabilized Approaches Lead To Accidents

According to the NTSB and FAA, unstabilized approaches are a key contributor to accidents on non-precision approaches.

That's especially true with non-precision approaches that have stepdown fixes inside the final approach fix (FAF).

When you're flying a non-precision approach with stepdown fixes, you're required to perform multiple power, pitch and altitude adjustments, all while flying in the clouds. The real problem is that all of these adjustments increase your workload in a critical phase of flight, and increase your chance for error.

Whether or not your approach has stepdown fixes inside the FAF, using the "dive and drive" method of descending immediately to the approach's minimum altitude can leave you in extended level flight as low as 250 feet above the ground in IMC. Obviously when you're that close to the ground and still in the clouds, your chance of something going wrong increases.

Fortunately, the FAA and Jeppesen are making things a bit easier and safer for all of us, by publishing a Continuous Descent on Final Approach (CDFA) for most non-precision approaches.

The Solution? Continuous Descent on Final Approach (CDFA)

When you fly a stabilized approach, your chances of an accident decrease dramatically. So what is a stabilized approach? According to the FAA and ICAO:

The stabilized approach concept is characterized by maintaining a stable approach speed, descent rate, vertical flightpath, and configuration to the landing touchdown point. Depart the FAF configured for landing and on the proper approach speed, power setting, and flightpath before descending below the minimum stabilized approach height; e.g., 1,000 feet above the airport elevation and at a rate of descent no greater than 1,000 feet per minute (fpm), unless specifically briefed.

So how do you figure out a continuous descent rate from the final approach fix? FAA and Jeppesen charts make that part easy.

(As a note, CDFA isn't required for Part 91 pilots, but it is strongly encouraged by the NTSB and FAA)

How To Figure Out Your CDFA

Let's start with Jeppesen charts, which are the easiest to use for CDFA.

If you look at a non-precision approach, like the VOR RWY 01 in Price, Utah below, you'll see a descent angle published starting at the FAF of 2.98 degrees. So if you start a 2.98 degree descent at WELEN and you continue all the way to the runway, you'll cross the threshold on descent path at a Threshold Crossing Height of 52' (assuming you break out of the clouds at the MDA of 6300' or higher).

So how do you descend at 2.98 degrees? Jeppesen includes a groundspeed/descent chart right under the profile view. Just pick your ground speed, and descend at the appropriate FPM rate starting at WELEN.

The FAA's charts also include a CDFA angle. If you look at the chart below, you can see it published in the profile view.

Unfortunately you need to dig a little more to get descent rates for the FAA, because they aren't included on the chart itself. The FAA has a separate Climb/Descent Rate Table:

What About Final Approaches With Stepdown Fixes?

So what happens if you're on an approach that has a stepdown fix inside the FAF?

Your descent can be a little more complicated, because you most likely will have two different descent gradients you need to meet: one to the stepdown fix, and one to the runway.

There are two ways you can approach this. First, you can figure out your descent rate to the stepdown fix, start descending at that rate, and then increase your rate of descent once you cross the stepdown. But the second, preferred method, is to delay your descent until you can meet your final descent gradient.

Jeppesen charts make this easy.

Look at the RNAV (GPS) RWY 3 approach to Canyonlands below. NERRI is the FAF, but since you have differing descent gradients along the final approach course stepdown fixes, the Jeppesen chart recommends you delay your descent until 6.6 NM to RW03, and then descend at a CDFA of 3.74 degrees.

An approach like this is more difficult to figure out with FAA charts, however. If you look at the same FAA chart into Canyonlands, you'll see that they only publish a CDFA angle from FATPU inbound. To figure out where you need to start your descent after NERRI for a CDFA, you'll have to do the math yourself.

CDFA Can Help Identify Difficult Approaches

Look at the RNAV-E approach to Steamboat Springs below. PEXSA is the FAF, but since you have differing descent gradients before and after WAKOR, the Jeppesen chart recommends you delay your descent until 3.4 NM to RW32, and then descend at a CDFA of 7.75 degrees. That's a descent rate of 1378 FPM at 100 knots groundspeed. When you have a descent gradient that steep, you really need to think about how proficient your IMC skills are, and how safely you can execute the approach.

If you're not completely comfortable flying a steep approach, it might be best to divert and try something else.

How Does It Apply To The Real World Of General Aviation?

So how does all of this apply in the real-world of Part 91 IFR flying?

The reality is when you're in the clouds, you're usually getting bumped around, and your flight path is never perfect. But that doesn't mean you can't use CDFA.

When you brief and plan for a CDFA on a non-precision approach, your approach will be more stable, regardless of the conditions you're flying in.

You'll have to make fewer power/pitch changes, and in general, the approach will be more comfortable (and safe) for you and your passengers.

What's Your Thought?

So what's your thought? Have you ever flown CDFA on a non-precision approach? If you're an instructor, do you teach students to fly CDFA? Tell us in the comments below.

Colin Cutler

Colin is a Boldmethod co-founder, pilot and graphic artist. He's been a flight instructor at the University of North Dakota, an airline pilot on the CRJ-200, and has directed development of numerous commercial and military training systems. You can reach him at colin@boldmethod.com.

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