dtuuri
Final Approach
Anything below category E and even category E below 5000' MSL, if I'm not mistaken, is less than 5 miles laterally. A normal 3° glide slope is 5 miles at 1500' AGL, again, if I'm not mistaken.
Challenger Jet down in Truckee CA 7/26/21
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Tarheelpilot
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So why would you be outside those limits. No reason to be further away
Everskyward
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Everskyward
It wasn't dark. Look at the time again...
dtuuri
Final Approach
Look at my reply to @Sluggo again. I'm not referring to the OP, but to the thought that nothing "good" can come from circling near circling minimums.
Everskyward
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So what you posted is a little irrelevant to this accident.
dtuuri
Final Approach
Ok, if you manage the approach to remain at or above MDA until final or thereabouts and can stay within your circling limits, more power to you. As a benchmark, a normal descent angle would be five miles @ 1500'AGL traffic pattern height, which is beyond most category limits.
dtuuri
Final Approach
No more so than Sluggo's post. Go jump on him.
Everskyward
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Sluggo never mentioned night ops.
dtuuri
Final Approach
I never mentioned it had anything to do with the accident, but that didn't stop you from butting in either, so?
Sluggo63
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I see what you're getting at. I don't agree. First, practical example. We used to circle Cat D for practice in big airplanes (Cat E when we were heavy), and we never exceeded the circling protected airspace (and that was the old, smaller one). There's a lot of room out there, and plenty of time to descend from 1500' to the runway. We used to fly visuals at 2000' AGL and it wasn't a problem, just needed a few more fpm initially when you started your base turn. These guys should have been at 1800' AGL and they still should have had time. One of the mandatory briefing items we had in the Air Force was "initial rate of descent" for the approach, which got us thinking about different approaches like this one.
Yes, a typical 3° GP has you at 1500' at 5 miles. But, you're not doing a straight in when you're circling. Those 5 miles are curved. They had at least 3.2 miles from the runway of protected airspace. Even in a heavier airplane you're flying no more than 2 to 2-1/2 miles abeam the runway on downwind.
I'm not casting aspersions on these guys. It was a challenging approach, for sure.
Tarheelpilot
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I guess if you want to do that straight in it would be hard to do but if you are willing to turn it would be an easy task. Staying within 3 miles of the runway in a category D aircraft doesn’t require super pilot skills or wizards.
dtuuri
Final Approach
Luckily, this TRK circling approach is NA at night, but what if it wasn't? The safest (not risk-free) method would be holding circling minimums until within 10° of final to have visual obstruction lighting and descending at twice the normal rate. You wouldn't fly an even higher traffic pattern to avoid the "no good" things, would you? From higher up I'd think you'd have a tendency to stray outside the 3 mile limit.
As for the crash audio, it sounded to me like they clipped trees a ways before the crash sequence began in earnest. Should have taken up tower's offer to come overhead first, I think.
dtuuri
Final Approach
I think you mean "the most" they had was 3.2 miles, which is half what they needed for a normal descent from circling minimums.
MauleSkinner
Touchdown! Greaser!
Whether straight-in or circle, that math seems to be a new concept for the overwhelming majority of pilots.
Tarheelpilot
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How do you figure that to be the case?
In larger faster aircraft the higher you circle the further you need to be from the runway to descend properly and maintain a power on stabilized approach. You don’t want to be at idle in a jet below 1000 AGL and fully spooled by 500 feet is required by many operations.
dtuuri
Final Approach
3°= 300'/NM, so from 1800' you need 6 NMs.
Tarheelpilot
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6 nm over the ground. Not 6nm from the airport. It’s a circling approach. Not a straight in approach. Also the distance is measured from the ends of the runways. 3 mile arcs off the ends of all the runways crests a rather large area. Your math is correct. Your starting point is not.
dtuuri
Final Approach
I had said, "TRK is NA at night, but what if it wasn't." It's the night circling approaches at unfamiliar airports that prompted me to take issue with @Sluggo's blanket statement that "nothing good" can come from circling at or near circling minimums when higher is available. In the day, I'm with you, higher is better. Even at night where I'm familiar with what lurks in the dark spaces. When it's dark and nasty and unfamiliar I prefer about a hundred feet above MDA until turning final and starting a normal descent. That can't be done at TRK, ASE and others, so night circling ops are NA even if they're not NA on the chart, IMO.
Tarheelpilot
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If you’re at or above MDA and within the circling protected area there is, by definition, nothing to hit. There is no reason to be outside of those parameters nor will it require an unstable approach to stay within them.
If you just have higher personal minimums than what the procedure and terps allow that’s fine. when I’m flying for fun I generally do as well.
dtuuri
Final Approach
Have you got circling areas on your moving map? If we both turn base at the same angle over the shoulder the higher one will be closer to the limit. I'm just not comfortable estimating where the limit is, since it isn't marked in anything I've flown. So, maybe you have better references? On the other hand, I am quite comfortable in my circling technique at slightly above MDA—more than guesstimating distances visually. Closer is better for me. Also, I would only make one change from MDA to descent. Your way, I'd have to start descending and then monitor MDA and level off again if I reach it before ready to turn final, then descend again when turning final.
That's it for me. Good discussion while we wait for the NTSB to figure out what caused this crash. G'nite.
Tarheelpilot
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All of the FMS equipped aircraft I have flown had the capability to display waypoints with DME arcs and radials on the map for reference. Utilizing the runway waypoints with a 3 mile ring makes for a useful tool.
When I’m flying my little GA airplanes I don’t circle. No where I need to get to bad enough to fly around like that in a piston airplane. At least not anymore.
martym
Pre-takeoff checklist
55% N1 is all it needs. The Challenger is a hard wing airplane so it would be a handful during circling even VMC circling maneuver such as this one.
In these weather conditions I do not comprehend why the crew opted for the RNAV 20 with Circle-to-land for RWY 11.
(Circling Minimum for CAT C a/c is 7700 ft MDA)
Flying the straight-in RNAV 11 (7720 ft MDA) would have been fairly easy and straightforward without the extra workload of a circling approach in reduced visibility.
The risk of overshooting the final approach course is very high on circling approaches and I suspect that the accident pilot flew the a/c into a G-load induced accelerated stall while overshooting the base-to-final turn and trying to save it with an aggressive manoeuvre.
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martym
Pre-takeoff checklist
They indicated in their communication with ATC that runway 20 was inadequate in length.
Fracpilot
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With the winds you posted above, that would be greater than a 10 knot tailwind. The 605 and most jets have a 10 knot tailwind limitation. The straight in to 11 would have exceeded that limitation. You have to include the gust. There’s a lot of terrain, GA and glider activity at TRK. Maybe one of those were a factor in his decision making. We will find out with the NTSB results
Yes 20 would’ve been too short for a 605 when you have a 7000 fr runway. The airplane is capable of landing on a 4600 ft runway. I know I have done it legally with APG.
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MauleSkinner
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The airplane may be capable, but a lot of pilots aren’t.
Tarheelpilot
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It’s a landing and take off limitation.
dtuuri
Final Approach
No. They were coming from the north, that's why. The winds posted earlier were from two opposite directions. I don't know which was pertinent to the accident time. Being a Challenger, I'd suppose they had wind info on their avionics display, so chose a landing direction based on that. But—there could have been a wind shift or shear down low they didn't know about.
MauleSkinner
Touchdown! Greaser!
If they were using their flight display instead of tower report to determine winds on the ground, they were even more screwed up.
RussR
En-Route
@dtuuri @Tarheelpilot - it seems you two are talking past each other. You're both partially correct, but from different perspectives.
Circling MDAs provide a minimum of 300 feet of obstacle/terrain clearance within the designated circling radius. But once you start descending, there is no more obstacle clearance until you are on final (and not always then, either). Thus, for a generic circling at night situation, consider this:
Assume Circling MDA is 1500 HAA (Height Above Airport). Yes, this means about a 5 nm descent at 3 degrees. Yes, it can be total flight track distance, meaning curved. But here's the problem. It's night. You're maybe on downwind a couple miles from the runway, well within the circling radius. You decide it looks like a good time to start a normal descent. BUT, that 1500 HAA Circling MDA is based on the 1200 ft hill that is just in front of you on your downwind. Or maybe on base. Once you start the descent, there is NO guaranteed obstacle clearance throughout that descent to the runway. Once you descend 300 feet, you hit the hill. Pretty straightforward.
The only place there is any protection at all is on final. On final, for a circling-only approach, a "20:1 slope" is evaluated, but only out to 10,000 feet from the runway end (so, ~1.6 nm). If obstacles penetrate this, circling is STILL allowed, since this is a "visual" segment and the pilot is expected to see and avoid those obstacles. If the obstacles are not lit, then the procedure is NA at night, because obviously the pilot can't see them then. But outside of that 1.6 nm, there is no evaluation of obstacles for this purpose.
So in short, there is no guaranteed protection at all when below the Circling MDA until closer than 1.6 nm on final. And even then, it's "don't hit the stuff you see"-type protection.
So whether you start descending from that 1500 HAA altitude on downwind or set up for a 5 mile final, either way there isn't much protection. It's no wonder that circling procedures at night are one of the most dangerous maneuvers in aviation and why many flight departments don't allow them.
Now, that said, it's not usually quite that bad. Obviously, lower approach categories usually have lower MDAs, so once you're within the next lower category's radius, you may have obstacle clearance again - but that's a lot of mental figuring to do when you're already low and slow.
And, of course, the above examples are of a circling-only procedure in isolation - if there are straight-in procedures to a runway, then there are by definition more protections for that runway, which would possibly help keep you safe(r) if you're circling to it off another procedure.
Circling MDAs provide a minimum of 300 feet of obstacle/terrain clearance within the designated circling radius. But once you start descending, there is no more obstacle clearance until you are on final (and not always then, either). Thus, for a generic circling at night situation, consider this:
Assume Circling MDA is 1500 HAA (Height Above Airport). Yes, this means about a 5 nm descent at 3 degrees. Yes, it can be total flight track distance, meaning curved. But here's the problem. It's night. You're maybe on downwind a couple miles from the runway, well within the circling radius. You decide it looks like a good time to start a normal descent. BUT, that 1500 HAA Circling MDA is based on the 1200 ft hill that is just in front of you on your downwind. Or maybe on base. Once you start the descent, there is NO guaranteed obstacle clearance throughout that descent to the runway. Once you descend 300 feet, you hit the hill. Pretty straightforward.
The only place there is any protection at all is on final. On final, for a circling-only approach, a "20:1 slope" is evaluated, but only out to 10,000 feet from the runway end (so, ~1.6 nm). If obstacles penetrate this, circling is STILL allowed, since this is a "visual" segment and the pilot is expected to see and avoid those obstacles. If the obstacles are not lit, then the procedure is NA at night, because obviously the pilot can't see them then. But outside of that 1.6 nm, there is no evaluation of obstacles for this purpose.
So in short, there is no guaranteed protection at all when below the Circling MDA until closer than 1.6 nm on final. And even then, it's "don't hit the stuff you see"-type protection.
So whether you start descending from that 1500 HAA altitude on downwind or set up for a 5 mile final, either way there isn't much protection. It's no wonder that circling procedures at night are one of the most dangerous maneuvers in aviation and why many flight departments don't allow them.
Now, that said, it's not usually quite that bad. Obviously, lower approach categories usually have lower MDAs, so once you're within the next lower category's radius, you may have obstacle clearance again - but that's a lot of mental figuring to do when you're already low and slow.
And, of course, the above examples are of a circling-only procedure in isolation - if there are straight-in procedures to a runway, then there are by definition more protections for that runway, which would possibly help keep you safe(r) if you're circling to it off another procedure.
NJP_MAN
Pattern Altitude
This could very well have been a circle in IMC conditions. Most of us have flown where you have good visibility higher up but as you descend into the haze or in this case smoke, the visibility gets to be lower than what the ground is reporting. Only when you're on the ground you wonder to yourself what made it so hard to see because now it looks better than the conditions you just flew through to get where you are.
dtuuri
Final Approach
It took awhile to zero in on our differences, I think. Your post was excellent, however, as a summary for TERPS circling criteria. I especially liked your reminder of why I like to keep close to the airport:
"The only place there is any protection at all is on final. On final, for a circling-only approach, a "20:1 slope" is evaluated, but only out to 10,000 feet from the runway end (so, ~1.6 nm). If obstacles penetrate this, circling is STILL allowed, since this is a "visual" segment and the pilot is expected to see and avoid those obstacles. If the obstacles are not lit, then the procedure is NA at night, because obviously the pilot can't see them then. But outside of that 1.6 nm, there is no evaluation of obstacles for this purpose.
So in short, there is no guaranteed protection at all when below the Circling MDA until closer than 1.6 nm on final. And even then, it's "don't hit the stuff you see"-type protection."
So in short, there is no guaranteed protection at all when below the Circling MDA until closer than 1.6 nm on final. And even then, it's "don't hit the stuff you see"-type protection."
Sluggo63
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I agree. It's a good conversation and you brought up some great points. I'm just going to add one more thing. When you're circling down low, if you're not accustomed to being there, there's an illusion which causes you to fly your pattern closer to the runway than you should be. Basically you tend to use the same visual clues when circling that you would during a normal traffic pattern which has you flying too close to the runway and causes you to overshoot or overbank.
This was a good discussion. I agree and I guess we'll see what the NTSB comes up with.
Cheers!
Capngrog
Pre-takeoff checklist
Is an aircraft of this class required to have a DFDR and CVR, or are the optional?
luvflyin
Touchdown! Greaser!
Something I'm wondering about. If it started out at AWEGA at 12,000 instead of 13,000, do you think it might have made some difference? Like is the airplane more of a handfull at the increased descent rate needed and maybe made them a little busier that could have led to getting behind the plane later down low?
EDIT: Turns out the controller gave him 12,000. Once again the VAS transcription was wrong. And he was way higher than that anyway.
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edessa
Pre-takeoff checklist
Bombardier delivers all of its challenger aircraft with CVR and FDR and 406 ELT installed.
This aircraft had major inspections done and painted in September 2020. It was on the market. Don’t know if it sold and the crew was new to the 605 or not. Time will tell.