Descending below field elevation while cirling

F

F01LA

Line Up and Wait
Joined
Sep 20, 2012
Messages
570
Display Name
Display name:
5446
Descending below field elevation while circling

I'm not instrument rated, just saw something in a pilot's memoir and wondered about it. Is it prohibited, dumb, or none of the above? This happened in the 60's in Wyoming. The author/pilot writes:

"The Rock Springs Airport was one of the few in the country that had a unique feature that allowed us to operate there at times when other airports would be shut down. This airport was built on a flat top mesa that rose up about 700 feet above the valley floor. It was possible to make an ILS approach to the west with a 200 foot ceiling and a very strong easterly wind, pull over to the north side of the airport after breaking out, drop down 150 or 200 feet below the airport elevation, fly around and line up on the runway, now flying easterly, hop up slightly and land visually.

I don't recommend that pilots who are not familiar with Rock Springs do this; I'm only saying that it is a possibility here. What's that? Did I ever do this? Well, if there are no more questions ... Actually, the circling approach FAR is a little flexible, but I have no idea if it has a specific allowance where you can circle clear of clouds, at 300 feet below the airport elevation, then climb back up and land normally. Let's just say that I was lucky enough to be able to get in and out of Rock Springs through the winter."
 
Last edited:
Circling altitudes are published as a height above the airport. If he is operating below the airport on an IFR flight plan I'd say it would not be legal.
 
91.175(c) Operation below DA/ DH or MDA. Except as provided in paragraph (l) of this section, where a DA/DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, below the authorized MDA or continue an approach below the authorized DA/DH unless—
(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and for operations conducted under part 121 or part 135 unless that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;
Click to expand...
Note that a climb to a landing is not an alternative. You might try arguing that tha altitude for circling isn't noted as DA or MDA, but in http://www.faasafety.gov/gslac/ALC/libview_normal.aspx?id=17273 the FAA notes:
The Aeronautical Information Manual) (AIM) defines minimum descent altitude, or MDA, as "the lowest altitude, expressed in feet above mean sea level (MSL), to which descent is authorized on final approach, or during circle-to-land maneuvering, in execution of a standard instrument approach procedure (SIAP) where no electronic glideslope is provided."
Click to expand...
 
Jaybird180 said:
Contact approach still seems legal.
Click to expand...
You have to be clear of clouds before you can request and be cleared for the contact approach. If the weather is so low that you have to circle below airport elevation, you'd almost certainly be unable to break out, and then request and obtain the clearance for the contact approach before reaching the MAP.
 
Velocity173 said:
Circling altitudes are published as a height above the airport. If he is operating below the airport on an IFR flight plan I'd say it would not be legal.
Click to expand...
I'm with McFly. I don't think that going below field elevation and then climbing back up to the runway would be considered a "normal rate of descent and normal maneuvering," and thus would violate 91.175.
 
Say the min circling alt is 300'. You are 50' below the clouds in your expert circle. Whilst circling, say close to abeam the departure end of the landing runway you look and notice you are at 280'. Heavens, what to do? Can you not correct and climb back to your circling MDA?
 
Captain said:
Say the min circling alt is 300'. You are 50' below the clouds in your expert circle. Whilst circling, say close to abeam the departure end of the landing runway you look and notice you are at 280'. Heavens, what to do? Can you not correct and climb back to your circling MDA?
Click to expand...
Not only can you, you'd better by golly do it ASAP. That MDA is just what the name says -- a minimum. It's OK to be be a bit high, but going even one inch low can, if combined with the right set of circumstances, result in hitting something. That's why I teach my instrument trainees to aim about 50 feet high initially when leveling at MDA, and then work down from there if and only if conditions allow doing that without busting MDA. If it's smooth enough and they are enough on their game, then maybe they do make it right down to MDA, but maybe they end up bouncing around between MDA and 20 feet high, or, depending on conditions, 50 high, or even up and down between MDA and 100 high (the PTS criterion for max deviation above MDA on a nonprecision approach). If, in the process, one happens to briefly drift or bounce 20 feet low, it would take an extraordinary collection of conditions including altimeter error, high wind, low temperature, etc, before you might hit something. That's why a minor deviation below MDA promptly corrected is acceptable on the IR practical test.

However, the poster was talking about deliberately descending several hundred feet below MDA while not yet in position to land from that point using "normal maneuvers and a normal rate of descent." That is a deliberate violation of 91.175 as well as an invitation to getting killed from running into something between the point you left the MDA and reaching the protected area aligned with the runway, or, if you then have to go missed, while attempting to climb from outside the parameters for which the missed approach profile has obstruction protection.
 
Re: Descending below field elevation while circling

F01LA said:
I'm not instrument rated, just saw something in a pilot's memoir and wondered about it. Is it prohibited, dumb, or none of the above? This happened in the 60's in Wyoming. The author/pilot writes:

"The Rock Springs Airport was one of the few in the country that had a unique feature that allowed us to operate there at times when other airports would be shut down. This airport was built on a flat top mesa that rose up about 700 feet above the valley floor. It was possible to make an ILS approach to the west with a 200 foot ceiling and a very strong easterly wind, pull over to the north side of the airport after breaking out, drop down 150 or 200 feet below the airport elevation, fly around and line up on the runway, now flying easterly, hop up slightly and land visually.

I don't recommend that pilots who are not familiar with Rock Springs do this; I'm only saying that it is a possibility here. What's that? Did I ever do this? Well, if there are no more questions ... Actually, the circling approach FAR is a little flexible, but I have no idea if it has a specific allowance where you can circle clear of clouds, at 300 feet below the airport elevation, then climb back up and land normally. Let's just say that I was lucky enough to be able to get in and out of Rock Springs through the winter."
Click to expand...
AVX on Catalina is very similar in that it is at the edge of a 1640' precipice from the sea surface adjacent. Many times the clouds are such that you have a ceiling at 1700, but no worries getting in because you have 10 miles or better underneath. As long as you know which rocks to aim for you can come in low and keep your speed up until the last moment with a quick climb to the threshold.
 
Re: Descending below field elevation while circling

Henning said:
AVX on Catalina is very similar in that it is at the edge of a 1640' precipice from the sea surface adjacent. Many times the clouds are such that you have a ceiling at 1700, but no worries getting in because you have 10 miles or better underneath. As long as you know which rocks to aim for you can come in low and keep your speed up until the last moment with a quick climb to the threshold.
Click to expand...
Since the lowest MDA at KAVX is 2220 MSL, just how do you get below the 1700 MSL cloud deck so you break out in the first place? In any event, even if you find a break in the deck and spot the runway, what Henning describes is directly contrary to the regulatory language of 91.175 no matter how familiar you are with the rocks (with which you may become fatally familiar if you try this stunt).
 
Re: Descending below field elevation while circling

F01LA said:
I'm not instrument rated, just saw something in a pilot's memoir and wondered about it. Is it prohibited, dumb, or none of the above? This happened in the 60's in Wyoming. The author/pilot writes:

"The Rock Springs Airport was one of the few in the country that had a unique feature that allowed us to operate there at times when other airports would be shut down. This airport was built on a flat top mesa that rose up about 700 feet above the valley floor. It was possible to make an ILS approach to the west with a 200 foot ceiling and a very strong easterly wind, pull over to the north side of the airport after breaking out, drop down 150 or 200 feet below the airport elevation, fly around and line up on the runway, now flying easterly, hop up slightly and land visually.

I don't recommend that pilots who are not familiar with Rock Springs do this; I'm only saying that it is a possibility here. What's that? Did I ever do this? Well, if there are no more questions ... Actually, the circling approach FAR is a little flexible, but I have no idea if it has a specific allowance where you can circle clear of clouds, at 300 feet below the airport elevation, then climb back up and land normally. Let's just say that I was lucky enough to be able to get in and out of Rock Springs through the winter."
Click to expand...

I am throwing in the BS flag...

The wind is NEVER out of the east in Wyoming...:no: Especially in Rock Springs.:nono:;)
 
Ron Levy said:
Not only can you, you'd better by golly do it ASAP. That MDA is just what the name says -- a minimum. It's OK to be be a bit high, but going even one inch low can, if combined with the right set of circumstances, result in hitting something. That's why I teach my instrument trainees to aim about 50 feet high initially when leveling at MDA, and then work down from there if and only if conditions allow doing that without busting MDA. If it's smooth enough and they are enough on their game, then maybe they do make it right down to MDA, but maybe they end up bouncing around between MDA and 20 feet high, or, depending on conditions, 50 high, or even up and down between MDA and 100 high (the PTS criterion for max deviation above MDA on a nonprecision approach). If, in the process, one happens to briefly drift or bounce 20 feet low, it would take an extraordinary collection of conditions including altimeter error, high wind, low temperature, etc, before you might hit something. That's why a minor deviation below MDA promptly corrected is acceptable on the IR practical test.

However, the poster was talking about deliberately descending several hundred feet below MDA while not yet in position to land from that point using "normal maneuvers and a normal rate of descent." That is a deliberate violation of 91.175 as well as an invitation to getting killed from running into something between the point you left the MDA and reaching the protected area aligned with the runway, or, if you then have to go missed, while attempting to climb from outside the parameters for which the missed approach profile has obstruction protection.
Click to expand...

Yeah, I'm not in the 'pro-descend-below-the-field-during-circle' camp. Just saying you can technically climb on a circle.
 
Re: Descending below field elevation while circling

N801BH said:
I am throwing in the BS flag...

The wind is NEVER out of the east in Wyoming...:no: Especially in Rock Springs.:nono:;)
Click to expand...

Not to mention the mesa isn't anywhere near 700 feet above the valley floor. Maybe half of that. I drove by the airport Monday evening so have seen it recently...
 
I've flown into Rock Springs a number of times and think it would be nuts to circle below the mesa top.
 
Everskyward said:
Don't worry, you can follow the MLOD and use your SVT and you will get there. :D
Click to expand...

MLOD....riiiiight! Gotcha, I'm on it...just as soon as the charging system is working...and it's up for annual again...and I'm sure that more stuff is needed...and....cowboy up! (since it's WWW)
 
Last edited:
Captain said:
Yeah, I'm not in the 'pro-descend-below-the-field-during-circle' camp. Just saying you can technically climb on a circle.
Click to expand...
Well, yeah, you can certainly bounce up and down between the MDA and the overhanging clouds. And if you accidentally descend below MDA, you'd definitely want to climb ASAP. But intentionally putting yourself in a position where you have to climb to reach the runway? :no:
 
Ron Levy said:
If you break out below a 200 foot ceiling, circling is not authorized because you're already below the circling MDA. That was the first flaw in the original post's thesis.
Click to expand...
Um, right. We were just kidding... I think. :confused:

I guess the person who claimed to do it wasn't kidding, though.
 
Everskyward said:
Um, right. We were just kidding... I think. :confused:

I guess the person who claimed to do it wasn't kidding, though.
Click to expand...

It's easy...just cancel IFR after descending 500' below the (200' agl) ceiling.
 
aterpster said:
What if the airport is in Class E Surface Airspace or Class D airspace?
Click to expand...


Hey....
Go easy on us... Out here in Wyoming we just got fire, and the wheel is still in development... Word around the cave is in the next 50,000 years they might figure out the alpabet and numbers.:goofy::goofy::D;)
 
What if the ceiling is only 200 feet in the immediate vicinity of the airport but is somewhat higher (in MSL) farther out, so that you break out and can see both the airport and the sloping cloud bases from well above circling MDA? You still couldn't legally descend below MDA while circling without a further clearance, but I'd think you could legally request a contact approach.

Not saying it would be a smart move, mind you, just that I don't see anything illegal about it.

Also, the OP said this was from the '60s... I wonder if the rules regarding descent from MDA might have been different then. It still seems like a rather "Wild West" mentality though.
 
I'm pretty sure there's a thing about not descending below the MDA until in a position to descend to land.
 
Re: Descending below field elevation while circling

Ron Levy said:
Since the lowest MDA at KAVX is 2220 MSL, just how do you get below the 1700 MSL cloud deck so you break out in the first place? In any event, even if you find a break in the deck and spot the runway, what Henning describes is directly contrary to the regulatory language of 91.175 no matter how familiar you are with the rocks (with which you may become fatally familiar if you try this stunt).
Click to expand...

You never climb above it, just depart LGB and stay underneath.
 
Hmmm. And all this time I had always thought an ATC instruction to "climb and maintain airport elevation or higher" was a salty story....

Along the lines of "The fog was so think I couldn't see the instruments"
 
Captain said:
Yeah, I'm not in the 'pro-descend-below-the-field-during-circle' camp. Just saying you can technically climb on a circle.
Click to expand...
The issue is not whether you can climb, but rather the limits to which you can legally descend.
 
Last edited:
Re: Descending below field elevation while circling

Henning said:
You never climb above it, just depart LGB and stay underneath.
Click to expand...
IFR? I don't think so. And the original question involve an instrument approach. You want to depart and stay VFR, that's another story.
 
Ron Levy said:
The issue is not whether you can climb, but rather the limits to which you can legally descend.
Click to expand...

No fair quoting me twice!

But if you are then I'm going to agree with you twice...so there.
 
You must log in or register to reply here.
Back
Top