A recent accident attracted a lot of people’s attention trying to figure out just how a commercial-instrument pilot with over 1,000 hours could descend below MDA and hit a hill depicted on the approach chart halfway from the FAF to the runway. The Epic E1000-series turboprop single was flying the RNAV(GPS) RWY 32 approach to Steamboat Springs, Colorado (KSBS) at 0719Z (0019 MST) and resulted in an apparent Controlled Flight Into Terrain (CFIT) event with no survivors. The late-model six-seat turboprop was equipped with a Garmin G1000 NXi integrated flight deck, FIKI deicing system, and Garmin’s Autothrottle and Autoland systems.
Human Factors Worth Pondering
The aircraft’s flight history is not currently accessible, but it’s been reported to leave Nashville, Tennessee, earlier in the day and stopped for fuel in Kansas City, Missouri. Based on Epic Aircraft’s advertised performance data, the two legs should have been about 2 and 2.5 hours, respectively. Estimating backward from the 0015 MST time of the accident, it probably left Nashville around 7 p.m. Central time. The NTSB will be looking at the pilot’s 48-hour history to determine just what the pilot was doing all day before the flight, but given the pilot was reportedly a businessman, and this was a weeknight, the pilot may have been busy all day.
Even if the pilot slept late, the accident occurred after 1 a.m. on the pilot’s body clock, so the pilot may not have been exactly “fresh as a daisy” at the time of the accident, which could be an IMSAFE factor. Of course, the Garmin GFC 700 autopilot in that aircraft can be a big workload reliever and mitigate the effects of fatigue on long flights, but it can’t eliminate the insidious cumulative effects of fatigue.
I’m also wondering whether the pilot had anything to eat during the stop in Kansas City or in flight, and consequently what his nutritional status was at the middle-of-the-night time frame of the accident. Personally, I’ve always tried to avoid flying hungry, which is why I always carry a few protein bars in my headset bag in case of a growling stomach. Nevertheless, that makes two possible IM-SAFE strikes against the pilot.
Weather
When the pilot took off from Kansas City, the nearest TAF to SBS at Hayden, Colorado (KHDN) about 16 nm to the west suggested reasonably good VFR weather at the destination from takeoff up until about one hour before arrival, albeit with a 2,500-foot scattered layer below the 6,000-foot ceiling. That would have been generally adequate for a night visual arrival. However, that 0000Z TAF also called for a drop to prevailing 800-foot ceilings by arrival time with temporary conditions of 400 overcast in light showers of snow and rain, which strongly suggested the need to fly an instrument approach.
Further, an hour before arrival, an updated TAF was issued forecasting even worse conditions (2SM -SHSNRA BR BKN009 OVC020) at the time of arrival. Even for the best approach, the forecast broken layer would be 400 feet below the MDA. The METARs issued during the flight tracked well with the TAFs, showing the cloud layers and visibility dropping well below visual conditions beginning at 0555Z. We don’t know whether the pilot was monitoring the updated weather forecast or even the METARs during the flight, but at this point, whether the pilot knew it yet or not, even an instrument approach to minimums was going to be dicey. On a side note, those who read my discussion of the accident at Quincy, Illinois, that happened in November 2025 in an earlier article in Instrument Aviator may be seeing some common threads here—darkness, deteriorating weather, issuance of lower weather forecasts after takeoff, and possible pilot fatigue and nutrition issues. Caveat aviator.
SBS has three SIAPs, all approaching from the south, like this flight. The forecast and reported winds appeared to be slightly favoring Runway 14, but to land on 14 would require circling at night in poor weather and mountainous terrain. Landing on Runway 32 with winds varying between calm and 5 to 6 knots on the tail should not have been a major issue, but the fly in the ointment was that of the three approaches, only two were legal to land on Runway 32 at night, and the pilot chose the third. That RNAV(GPS) RWY 32 chart shows that at night landing straight-in on Runway 32 and circling to 32 are both “NA.” In that situation, flying that approach would require circling to Runway 14 at night, and even that was limited to the southwest side of the runway due to terrain on the northeast side, with no VGSI on the landing runway. Further, the reported weather then was SCT005 BKN016 OVC024, so the ceiling was about 600 below the MDA. Even the overcast layer was only 200 above MDA, with that broken layer below the MDA, plus another scud layer below that.
Using one of the other two SIAPs would have allowed a lower MDA of 8,140 MSL (about 1,250 AGL), which was below the broken layer but still with the scud layer below that. The RNAV-E approach would have allowed landing on Runway 32 but because of the obstructions on final, it would require a 7.75° approach angle for a direct approach, making a straight-in nearly impossible but having the advantage of allowing descent below the broken layer before visual contact. The alternative was diverting to HDN that’s 16 nm away with its ILS and LPV approaches, arriving in the middle of the night with no pre-arrangements made. The pilot might have faced a complicated decision late at night after a long day, which is a tough corner to be in.
Vertical Guidance Trap?
So, how is it this pilot left the MDA at night with two layers below and began descending to the runway? I’ve seen some speculation that the pilot might have seen vertical steering from the Garmin +V advisory vertical guidance mode and followed it down. However, Garmin tells us the criteria for being included in the database for +V advisory vertical guidance are:
- It must be a GPS-approved approach.
- There must be a non-zero vertical angle for the approach.
- A valid geoid height for the runway must exist.
- The approach does not contain LNAV/VNAV or LPV service levels.
Referencing that Quincy, Illinois, wreck again, there are common threads here: darkness, deteriorating weather, issuance of lower weather forecasts after takeoff, and possible pilot fatigue and nutrition issues. Caveat aviator.
Additionally, the GPS unit must have a SBAS (WAAS, EGNOS, GAGAN or MSAS) signal of sufficient integrity. This means the GPS Status page must show “3D Diff Nav.” If all these requirements are met, the Garmin navigator will automatically upgrade the approach from LNAV to LNAV+V. However, as you see in that chart depicted here, while this is a GPS-approved approach with no LNAV/VNAV or LPV options in the minima table, there is no vertical angle on the SIAP chart (as there is on the RNAV-E). That means there should not have been a glide slope/path vertical steering needle presented.
Nevertheless, my calculations and a review of the approach chart and sectional suggest that a straight-line descent from 9,100 at WDCHK to the runway would hit the 8,000-foot terrain near the depicted 8,353-foot obstruction halfway between WDCHK and ACDIY. If the pilot started down without adequate visual references aiming straight for the runway, that would fit with terrain impact below the MDA after the hard 9,100-foot floor at WDCHK. Did this pilot start down from the MDA without adequate view of at least one of the 10 items in FAR 91.175(c)(3) required for operation below the MDA/DA (not all of which are even available at SBS), believing somehow that there was adequate obstacle clearance on a path from the FAF to the runway? Was he relying on synthetic vision? Did he see a few lights out there between the clouds and just “go for it”? We’ll never know, but there’s a lot we can learn from this accident about everything from IMSAFE considerations to the reasons for procedure notations to the severe risks of busting an MDA at night in mountainous terrain.
A New NOTAM
Six days after the accident the FAA issued an FDC NOTAM making the RNAV Z RWY 32 approach “NA” until at least Oct. 1, 2026. While the FAA gave no indication why they did this, it may have something to do with that “Visual segment – Obstacles” note. FAA Order 8260.3G (TERPS) talks about visual segments, but only in respect to helicopter-only (COPTER) approach procedures. InFO 24005 “Instrument Approach Operations with a Visual Guidance Fix (VGF) and an Extended Visual Segment” speaks to some special procedures involving “Required Navigation Performance Approach (RNP APCH) procedures that uniquely offer the flight crew continuous advisory lateral and vertical guidance in an extended visual segment leading to the landing runway threshold,” but this isn’t that. Sometimes approaches have a MAP more than half a mile from the landing area, and the notation “Proceed VFR” or “Proceed Visual” is added from the MAP and an obstacle evaluation is conducted in procedure development, but this one doesn’t have that. As it stands, I’m wondering if the FAA is reconsidering the presentation of this approach.
Advisory for a Reason
There are many advantages to the Continuous Descent Final Approach for which +V provides advisory guidance, especially for heavier, faster aircraft like bizjets. I emphasize “advisory” because this system merely draws a straight line from the final approach fix at the minimum FAF altitude down to the runway but does not guarantee either staying above intermediate stepdown fixes or obstruction clearance below the MDA. Further, because there is zero altitude tolerance below the MDA, you must begin your level-off well above the MDA to ensure you won’t bust it while looking for the runway. Doing that will put you closer to the runway above the normal glide path, delaying seeing the runway and increasing the descent rate needed in close to land in the touchdown zone.
For these reasons I stress to my instrument trainees that the classic “drop-and-drive” technique for non-precision approaches may provide greater chance of success than +V when the ceiling is near the MDA, but I’m not sure that’s generally well taught in initial and refresher instrument training.
Another unknown regarding this pilot and flight is whether he was in the habit of exclusively flying approaches with vertical guidance (ILS, LPV). If then presented with an advisory glideslope and presenting the IMSAFE shortcomings mentioned, he might instinctively follow that guidance without due reflection.
It’s important to regularly train on NPA with step-downs like a localizer approach and reboot the hand/eye/brain loop for descend, level off, add power, prepare for the next altitude, configure, watch airspeed, etc… Do it on the autopilot, and also do it by hand. Bear in mind that “non-precision approach” is a kind moniker for an imprecise approach.
As I said in the article, there should not have been any vertical guidance displayed on this approach.
Yes, “should” not. Even if there wasn’t, I have noticed many times in students and myself that after flying several approaches with vertical guidance, there can be hesitation/delay when mentally shifting gears to the leveling off world.
Lastly, the pilot could have been expecting advisory guidance and not getting it, gotten further behind the airplane by fumbling with buttons and settings, not slowing down, not configuring properly and on time, etc…
YT contains some post-mishap daytime re-flights on that approach; it should be known whether Garmin navigators present a +V advisory GP there or not.
But it IS known that +V may be displayed even with obstacles piercing the 34:1 and 20:1 clearance surfaces. I believe this is due to information missing from the raw data that is supplied for Garmin to build their navigator procedures database.
So Ron’s excellent article raises the question for me, how does Garmin Safe Return select suitable procedures? Will it accept a 2-D approach, and if so, does it guard against obstacles during a CDFA?
Garmin told me Safe Return only uses airports with an approach that has a valid glide slope/path (ILS, LPV, LNAV/VNAV), so it would not use KSBS.
“However, Garmin tells us the criteria for being included in the database for +V advisory vertical guidance are:
First, please share a link to the document where Garmin tells us that criteria.
Second, the non-zero vertical angle, known as the VDA as published by the FAA for the approach, is no longer a criteria. There are a number of approaches in the database, including the KSBS RNAV RWY 32 under discussion, where the published VDA is zero but Garmin calculates the angle from the FAF to the TCH and then displays the +V based on that calculation. In fact, Jepp displays the computed angle on their plates even though the FAA plates do not. They have been discussed on various aviation forums, notably Beechtalk. You may learn a lot by perusing the discussion of this accident there.
It is pretty clear the KSBS accident pilot was following the +V guidance. It is clear he absolutely should have not flown the approach at night, and stopped at the MDA until he had the 91.175 criteria in sight. Those were pilot error without doubt. But whether because he misunderstood what +V meant, or whether he thought he had the 91.175 criteria in sight, or simply thought he could get away with it, he was following that guidance almost perfectly when you look at the flight path.
Caveat aviator indeed. +V has several instances where it guides you right through terrain. Everyone should understand that the MDA is absolute unless you can see from there. +V for CDFA is useful, but in this case it was deadly based on its misuse.
What is Needed to “Upgrade” an Approach From LNAV to LNAV+V | Garmin Customer Support
If that’s no longer accurate, perhaps you should bring that to Garmin’s attention. As for what is “pretty clear”, absent full CVR and FDR data (which I don’t think this plane had), I can’t say anything is quite that clear. But your caveat is indeed accurate, and something I teach pretty hard with my instrument rating and IPC trainees. I believe Instrument Aviator is preparing an article addressing this in depth.
Thanks for that link. Frustrating there is no date on that article. Indeed it is easily shown that +V approaches exist for some that do not have a published VDA, so it is longer accurate, though hard to tell when it changed.
What about terrain warnings? Major airlines teach that a “pull-up” warning requires immediate action, and it’s not an option to ignore. Surely the pilot (and likely passengers) were listening to continuous “pull up” warnings at some point shortly after descent from the MDA until impact. In my own plane, I might choose to ignore a terrain warning during day VMC and can visually verify I can clear the terrain, but I would never ignore a night and/or IMC terrain warning. I’m not actively instructing, but stressing the proper reaction to terrain warnings is at least as important as meeting the criteria to descend below MDA, if not more, IMO.
I’m not completely sure of which options this aircraft may have had so I can’t say for sure whether it would have had some sort of terrain warning system, but what you say is indeed possible. However, absent a CVR, we’ll never know what they heard.
And don’t call me Shirley.
I believe the terrain warnings were suppressed automatically and were not displayed. Garmin TAWS-B implementations suppress terrain warnings when on an approach with vertical guidance, ie a glideslope. And it does it if that glideslope is +V. The TSO requires this behavior, but whether it requires it for +V is probably ambiguous at best. Regardless it is how Garmin implementations seem to work.
if you want to see it yourself, download the Garmin GTN/G600 PC Trainer software (free – link below), and set up and fly the KSBS RNAV 32 approach coupled to the glideslope. No terrain warnings generated even as it flies right through the ground.
https://www8.garmin.com/support/collection.jsp?product=010-00478-00
Pilots who haven’t flown in the mountains very much usually don’t understand what they are up against. The wind on the runway might only be reported at 5 or 10 knots, so they think, “hey, no big deal.” But the wind tumbling across the mountains as they shoot the approach can be so violent that the autopilot is following the approach even while the pilot is being shaken around so badly that he can’t even read the instruments. At some point the autopilot can’t keep up with it either.
As for terrain warnings, I have been right on the approach into Aspen with needles centered and still gotten TAWS warnings. Then you look out your left window and it looks like your wingtip is about to scrape granite.
When I was young, there were some rather wealthy folks in Dallas with a Learjet that liked to vacation in Aspen. This would have been back in the 1960’s. We didn’t have much of the equipment we have today back then, but it was standard procedure to fly to Aspen and circle overhead at high altitude and take a look. If you like what you see, you land. If not, you just go back to Dallas.