Offset VOR/DME approaches are within the skill set of well-rounded pilots. Sure, VOR approaches are few and far between these days, and their numbers are dwindling, but you never know when you may need one, particularly in a diversion scenario. Additionally, remaining proficient in VOR/DME approaches will help you maintain many other elements of proficiency quite well.
The VOR/DME RWY 13 at KCKN is a great case study. It requires both a thorough understanding derived from a solid preflight briefing and good situational awareness during execution.
At first glance, we see that we’ll be flying away from the GFK VOR, our source of navigation, on this approach. The radial we’ll be riding is offset from the runway centerline by 31°, which is not a small amount.
Considering the added challenge of this approach, it’s worthwhile to note that the Minimum Sector Altitude is 3,300 MSL within a 25 NM radius of the GFK VOR. That’s a generous amount of space, but the threshold of our target runway is at 23.4 DME—right on the edge of the MSA radius.
The increased odds of needing to go missed are baked into this approach, so let’s review the procedure, even before mentally flying the main approach. Climb to 2,000 ft (always at full power), then perform a climbing left turn to 2,500 heading 250°. We’ll intercept GFK R-097 and proceed outbound (heading 277°) to WIRUV, which is DME 18.8. Perform the published missed approach hold at WIRUV.
First, we should think about our arrival. The approach plate indicates there are some directions from which we cannot arrive if we plan to use this approach. Text in the planiform view of the approach plate states that we can’t use this approach if we arrive from a direction between the acute angle defined by GFK VOR R-038 and R-143. So, we’ll likely be given vectors by ATC, or we’ll need to ask for them. Also note that if we arrive by first flying over the GFK VOR established on R-097, we can avoid the published procedure turn.
Regardless of how/where we enter, we need to be at or above 2,500 MSL. As we’re about to see, being much higher would not be advantageous and would necessitate a pretty sporty rate of descent.
As we fly the approach, our DME will be increasing. It’s important to know the DME of the three fixes to measure our progress. Upon passing WIRUV at the maltese cross, we may begin our descent. The runway threshold and MAP are now 4.6 NM away.
We don’t have a glideslope indicator, so we must engineer our descent. This is a back-to-basics moment. Use pitch to control airspeed and throttle to adjust rate of descent. Big fluctuations in descent rate make the approach less predictable, less controllable, and ultimately less safe, so smooth control inputs are a must.
Given a ground speed of 90-100 knots, we can descend at 500-600 fpm from WIRUV with a 3.17° glideslope to reach minimums about 2 nm from the threshold/MAP. Things happen quickly here, so precision is key.
Given that we’re flying a radial that is at a 31° angle to runway heading, precise glidepath management is more crucial than that for a more traditional approach, such as with a localizer. What are otherwise minor glidepath deviations, easily corrected when breaking out, become magnified and can turn a planned straight-in to a circle to land, or even a missed approach.
Your briefing should include more than just a careful analysis of the approach plate and the other usual factors, such as weather. Ideally, your briefing begins days before your flight by practicing with a sim. If you don’t have access to a sim, chair flying is always a great alternative.
Fly the approach in CAVU to build a mental image of the environment and get a feel for the timing of the approach. Then practice with high ceilings, then minimums. Once you’ve got that down, add various wind speeds and directions.
Given that there’s a reasonable chance of needing to go missed, practice that element of the flight as well, including entering and performing the published missed approach hold.
Yes, I know you will almost certainly be using technology and an autopilot to fly the approach in real life, so be sure your navigation database is up to date before launch.
But, even if you plan to use a slick system like a GNS for this approach, having hand-flown it a bit with a simulator or with your eyes closed in an easy chair will make you much safer and feel more relaxed flying this, or any other old-school approach, knowing that you can. With a sim or chair flights, you already have.