RED FLAGS in RNAV Approaches: What Every IFR Pilot Should Know
- Dan George
- 1 hour ago
- 4 min read
With GPS and its associated RNAV approaches, many smaller airports without traditional ground-based navaids like ILS or VOR are now accessible in IFR conditions. At first glance, these RNAV approach plates—published by the FAA—appear standardized and routine. But beneath the familiar format, some RNAV approaches carry far greater risk than others.
Unfortunately, there are no blaring alarm bells on approach plates for such riskier approaches. Pilots must learn to spot the subtle cues that indicate when an approach might push the limits of their aircraft—or their proficiency.
Below, we’ll explore several red flags to watch for on RNAV approach plates, using real-world examples to illustrate how to spot them and fly safer.
1. Visual Descent Angle (VDA): The Steep Descent Trap
Here’s the RNAV approach into Steamboat Springs, Colorado. At first glance, there are no big red flags screaming, “I am a scary approach!” Just another profile view with a nice clean line descending to the runway.
But let’s zoom in.
The vertical descent angle (VDA) from the step-down fix WAKOR to the runway threshold is 7.75 degrees. Let that sink in. A normal glidepath is 3 degrees. This is a slam-dunk approach—steep, fast, and unforgiving.
And here’s a little trap: that VDA only applies from WAKOR to the runway. It doesn’t tell you anything about the segment from the FAF (PEXSА) to WAKOR, even though the profile line looks like one continuous slope. It’s not. You’re going to have to manage a fairly normal descent at first, and then pull the power way back to make that sharp final dive to the numbers.
2. Course changes when you least want them
You’d expect a final approach course to point you pretty much straight at the runway. But not here. From MABKY to PEXSA, you’re flying 353 degrees. Then right at the FAF—right as you’re configuring for landing—you’re turning to 323 degrees. That’s a 30-degree heading change on final. You’re busy enough at the FAF. Adding a course change there is like juggling while tap dancing. It’s a recipe for instability if you’re not ready.
3. High Altitude, High ground speed, high workload
Now let’s layer on the altitude. We’re flying this approach above 8,000 feet MSL. Indicated airspeed might say 85 knots, but your true airspeed is way higher, and so is your ground speed—well over 90 knots in our case.
That bumps us into Category B minimums which carry a higher visibility requirement, and more importantly, it makes our descent angle even steeper. The faster you go over the ground, the more aggressive your descent has to be to stay on path. That means lower power, tighter margins, and more room for error.
4. No VDA? Uh-OH
Let’s switch scenes. The RNAV to Runway 2 at Brainard doesn’t even give us a VDA. Instead, there’s a note that says: “Visual Segment – Obstacles.”
Translation: there’s stuff in your way between the MDA and the runway threshold, and a stable glidepath can’t be safely drawn—even for advisory use. Jeppesen charts do show a descent angle here (about 3.5 degrees), but if you don’t have a Jepp subscription, you’re flying blind. FAA charts leave it up to you to interpret what that warning really means.
5. circling-like activities
Another quirk on the Brainard approach? The final course isn’t even aligned with the runway. You’ll see it if you check the airport diagram—the approach arrow clearly isn’t pointing straight down the centerline. This is where things start to feel more like a circling approach, even though it might technically be straight-in. That means lateral corrections while descending, which again ramps up workload.
6. The secret of the stipple
Ever notice that little shaded triangle—or stipple—at the bottom of some profile views?
On the RNAV to Runway 8 at Laconia, you’ll see it. It means the visual segment from the decision altitude to the threshold is obstacle-free within a 34:1 slope. In other words, you can fly a smooth, continuous descent all the way to the numbers.
But now look at the RNAV to Runway 1 at Franklin County. It has LPV minimums and vertical guidance too… but no stipple. Why? Because there’s a 305-foot obstruction right at the field. That’s enough to violate the 34:1 slope. You’ll still get vertical guidance on a WAAS-equipped unit, but you better have a plan for going visual and maneuvering around obstacles.
7. Short runway + steep descent = high risk
One more example: the RNAV to Runway 33 at Kingston. The chart says the runway is 3,100 feet long, but the available landing distance is only 2,630 feet—thanks to a big displaced threshold. You’ve got vertical guidance with an LPV and a glidepath of 3.59 degrees, which is already on the steep side. That gives you very little room to bleed off energy once you touch down. If you’re fast, you’re not stopping on time. This is one of those approaches where you want to be fully configured early and fly it like you’re landing on a postage stamp.
Approach plates may look standardized, but that doesn’t mean the approaches themselves are.
Some are straightforward. Some are monsters in disguise.
So don’t let the clean layout fool you. Look for:
Extreme descent angles (anything over 3° is worth a closer look)
Course changes at or near the FAF
High elevation and high ground speeds
Lack of VDA or stipple
Offset final courses
Short runways and displaced thresholds
Recognize the red flags early—on the ground, in your preflight briefing—so they don’t bite you in the air.
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