Question about circling

[spiderweb]

Sorry about deleting the last post, but here's another opportunity to laugh at me. I have a question about circling. I know that one must maintain the circling MDA until one can make a normal descent and landing. This makes sense. If flying at, say, 500 AGL, one doesn't want to descend until final (probably). But what about that Aspen approach? There, the circling minimums are 10,200' with the airport elevation at 7,820'; thus 2,380' AGL. Now, let's say one wanted to circle to land on Rwy33; how long does one have to stay at that minimum?

I think I know the answer; correct me if I'm wrong. If I popped out before the MAP (MAFMU), I could join downwind, and actually begin descending right away, so as to get to pattern altitude. The reason I can descend so early is that I now have the field, and in order to get myself in a position from which I am continuously able to land, I have to descend. No?

But I have another question. Let's say that we're landing Rwy15. I break out before three miles before the MAP. I can see that I can perform a normal descent from here (4.4 miles from the runway). I believe I am correct in understanding that I may now descend below the MAP to make a normal landing since I have the runway, right?

What if I break out before the FAF and have the runway from there--can I descend below printed minimums? I'm so used to having the hood on until the MDA, right before the MAP!

 

[RobertGerace]

Ben,

Please keep posting! Right, wrong, or indifferent I learn from your posts. (I'm not going to take this one on ) My answer is that I don't circle. (That's not entirely true...I'll circle at 1000 agl during the day if the ceiling is 1,500 and it is just more convenient because of wind.)

But a 'for keeps' approach in the mountains? Not I.

 

[bbchien]

Sorry about deleting the last post, but here's another opportunity to laugh at me. I have a question about circling. I know that one must maintain the circling MDA until one can make a normal descent and landing. This makes sense. If flying at, say, 500 AGL, one doesn't want to descend until final (probably). But what about that Aspen approach? There, the circling minimums are 10,200' with the airport elevation at 7,820'; thus 2,380' AGL. Now, let's say one wanted to circle to land on Rwy33; how long does one have to stay at that minimum?

I think I know the answer; correct me if I'm wrong. If I popped out before the MAP (MAFMU), I could join downwind, and actually begin descending right away, so as to get to pattern altitude. The reason I can descend so early is that I now have the field, and in order to get myself in a position from which I am continuously able to land, I have to descend. No?

But I have another question. Let's say that we're landing Rwy15. I break out before three miles before the MAP. I can see that I can perform a normal descent from here (4.4 miles from the runway). I believe I am correct in understanding that I may now descend below the MAP to make a normal landing since I have the runway, right?

What if I break out before the FAF and have the runway from there--can I descend below printed minimums? I'm so used to having the hood on until the MDA, right before the MAP!

The object of any insturment approach is to land. If you break out well prior to D11.0 10,200 you can descend as long as you are in a continuous position to land (within the category A one mile radius of the runway end. If you do this much before DME 11, however, the Granite will reassure you that you need to be at least at 9,500. If you are in a continual position to land you MAY descend below circling minimums. And I assure you, form 10,200 the problem is not that you don't have enough altitude.

But you have to see this valley from the air (abeam the south end of the runway) before concluding that you might land on 33. You have to be able to drop like a controlled rock over Maroon Creek road, or you ain't a gonna make it. Centurions with barn door flaps can make it, in a max slip. Doesn't look that way from the ground. Buttermilk doesn't look like much of an obstacle. But it is.

The key is "continuously in a position to land".

 

[gibbons]

Remember that the MDA is the minimum descent altitude when IMC, not when VMC. Once VMC you can make a normal pattern and approach.

The "gotcha" of the circling approach is to descend below MDA because you have the runway in sight, and then lose the runway on downwind or base and go IMC again. Now you're below MDA, IMC, and on a course that probably doesn't work well for the missed approach procedure. This is a bad situation and you have two options: 1) Climb and confess; 2) Poke around until you find the ground. Your choice.

Circling approaches are fine when there is a definite ceiling and once you're under it you remain VMC. It's when the clouds are low and scattered, like after a summer rain, that the circling approach can really sucker you in. Be careful out there.

Chip

 

[Fast n' Furious]

Chip, a little clarification/amplification to your post. If you fly an approach to MDA in IMC or VMC, you have the exact same required obstacle clearance (ROC). This is why it is vital, as you note, to maintain MDA or higher, until you are in a continuous position to land. Unfortunately there are many instances of folks flying to MDA, and into VMC conditions, leaving the base or downwind early, and crashing. Good post. Ben, tear up your copy of the Aspen approach. You're not going. I'm publishing the NOTAM tonight.

 

[spiderweb]

There's two questions, I see

OK, I'm home now. I see the answer to my question about descent below the MDA is found in 91.175(c). So. the answer to the question, If I get to the MDA before the MAP, may I descend? is, yes, provided the requirements of 91.175(c) are met--1) continuously in a position from which a descent to a landing on the intended runwqya can be made at a normal rate of descent, etc., 2) you have enough flight vis, and 3) you have the required runway visual references.

But I still don't have an answer to the other question. Say you are on an approach like this, with stepdown fixes. You still have a couple more stepdown fixes to go, when you break out below the clouds, and have the runway in sight, in all of its glory. Obviously, you may cancel IFR when 500 below the cloud deck and land under VFR (i.e., disregard the rest of the procedure). What I'm asking in this second question, though is this: assuming you stay IFR, can you descend below those intermediate stepdown minimum altitudes now that you have the runway in sight, with all the vis requirements, etc? In other words, does the "descent below the MDA" rule apply to minimum altitudes on stepdowns?

I cannot find a reference in the AIM or FAR!

 

[spiderweb]

Ben,

Please keep posting! Right, wrong, or indifferent I learn from your posts. (I'm not going to take this one on ) My answer is that I don't circle. (That's not entirely true...I'll circle at 1000 agl during the day if the ceiling is 1,500 and it is just more convenient because of wind.)

But a 'for keeps' approach in the mountains? Not I.

I agree with you. I think it is probably best to stay at or above those minimums, even in VMC, because you know they keep you safe.

 

[Fast n' Furious]

Lemme see if I can explain this with my TERPS hat (that's a joke Ben!) on. First off, TERPS has nothing to do with flying an instrument procedure. It has everything to do with designing one though and if you fly one without respecting the design, you put yourself at peril. An MDA is designed to hopefully get you into visual conditions, to a place where you can aquire the airport/runway/whatever, maintain required obstacle clearance (ROC) and stay that way until you are in a continuous position to land. A step down altitude is used purely to give the approach lower mins by identifying obstacles in the trapazoid and providing ROC over that obstacle. Decent from a stepdown, even when in visual conditions, may not provide adequate ROC to the landing runway given that there may be additional stepover obstacles ahead. Is that in the FAR/AIM or even in Part 97, I don't know but a stepdown should not be considered as a mini MDA/mini MAP.

 

[spiderweb]

Decent from a stepdown, even when in visual conditions, may not provide adequate ROC to the landing runway given that there may be additional stepover obstacles ahead. Is that in the FAR/AIM or even in Part 97, I don't know but a stepdown should not be considered as a mini MDA/mini MAP.

That's what I was looking for. I have always felt that it would be smart to follow stepdowns, even if you are flying under VFR. After all, they were put there to help keep you safe, so why not honor them no matter what rules you are flying under.

My paranoia, though, stems from the fact that the oral exam looms large now that the X-C is out of the way. If my DPE asked me, "Can you descend below the MDA?" I would know how to answer him, and where the reference is. If the trickster set me up with something like:

"You are flying on a severe clear day and ATC clears you for an approach that happens to contain stepdown fixes. You can see the airport from 50 miles away. Can you ignore the stepdown fixes? Remember, you weren't cleared for the visual approach, but for this specific approach with stepdown fixes."​

Now, I can answer with your words: "Decent from a stepdown, even when in visual conditions, may not provide adequate ROC to the landing runway given that there may be additional stepover obstacles ahead," and the part that clears it all up: "a stepdown should not be considered as a mini MDA/mini MAP [emphasis mine." If you're cleared for a visual, this is a whole 'nother approach. Cleared for an approach that has stepdown fixes, you gotta honor 'em.

Thanks! :zap!:

 

[Fast n' Furious]

With very few exceptions if you mention TERPS criteria to an examiner of any stripe....watch for the aneurysm. Good luck!

 

[gismo]

That's what I was looking for. I have always felt that it would be smart to follow stepdowns, even if you are flying under VFR. After all, they were put there to help keep you safe, so why not honor them no matter what rules you are flying under.

My paranoia, though, stems from the fact that the oral exam looms large now that the X-C is out of the way. If my DPE asked me, "Can you descend below the MDA?" I would know how to answer him, and where the reference is. If the trickster set me up with something like:

"You are flying on a severe clear day and ATC clears you for an approach that happens to contain stepdown fixes. You can see the airport from 50 miles away. Can you ignore the stepdown fixes? Remember, you weren't cleared for the visual approach, but for this specific approach with stepdown fixes."​

​

Ben, I'm certain that any rational DE will accept an answer that's more conservative than the rules allow such as "The rules may allow it, but I'm not willing...", if you get tossed a question like this one.

That said, unlike any clearance that includes an altitude to maintain, climb to, descend to etc. an approach clearance always implies that you may descend at will as long as you have conditions that the FAR's require for leaving the safe haven of the minimum altitudes on the approach chart, and you are continuously in a position to land without making radical maneuvers. To decide whether to do this or not on a specific approach dictates that you consider what established the minimum altitude. In most cases (especially in the flatlands) it's to provide the Terps required separation from underlying obstacles and terrain, and in such a case the only time I would personally consider going lower than I needed to reach the runway without an excessive descent would be when the object to avoid is a tower or building I can clearly see well enough to safely pass laterally. In the mountains it seems as often as not, the minimum altitudes are affected as much by limitations created by the need to break off the approach in IMC (the missed procedure). In that case an early descent below the published minimums (be they prior to the last stepdown or not) is likely to be both as safe as and more comfortable than a steep descent from close in as long as you have good visibility.

 

[bbchien]

And indeed it was shagginess that killed the G3 going into Aspen. You might have the airport at 11.0DME 10,200, but at 11.2DME 10,000 you might be in a cloud. VERY VERY bad.

 

[spiderweb]

Thanks guys. I'm learning every day, here!

 

[Ed Guthrie]

The object of any instrument approach is to land. If you break out well prior to D11.0 10,200 you can descend as long as you are in a continuous position to land (within the category A one mile radius of the runway end. If you do this much before DME 11, however, the Granite will reassure you that you need to be at least at 9,500. If you are in a continual position to land you MAY descend below circling minimums. And I assure you, form 10,200 the problem is not that you don't have enough altitude.

The above answer appears to ignore the second requirement of 91.175(c)(1)--"...at a normal rate of descent using normal maneuvers...". If an aircraft is below MDA it should be descending at a normal rate to a landing point. If the aircraft descends below MDA, levels off, and continues towards the intended landing point the aircraft obviously isn't in a position to use a normal descent rate because otherwise, to use that descent rate, the aircraft would need to continue descending.

The key is "continuously in a position to land".

The key is meeting all conditions:

1. Continuously in position to land
2. A normal rate of descent
3. Normal maneuvers

If the aircraft will violate any of those three conditions it should not be below MDA.

Ed Guthrie

 

[Ed Guthrie]

That's what I was looking for. I have always felt that it would be smart to follow stepdowns, even if you are flying under VFR. After all, they were put there to help keep you safe, so why not honor them no matter what rules you are flying under.

My paranoia, though, stems from the fact that the oral exam looms large now that the X-C is out of the way. If my DPE asked me, "Can you descend below the MDA?" I would know how to answer him, and where the reference is. If the trickster set me up with something like:

"You are flying on a severe clear day and ATC clears you for an approach that happens to contain stepdown fixes. You can see the airport from 50 miles away. Can you ignore the stepdown fixes? Remember, you weren't cleared for the visual approach, but for this specific approach with stepdown fixes."​

​

Ben, what the DPE wants to hear is, "91.175 states: "...no person may operate an aircraft under IFR below - (1) The applicable minimum altitudes prescribed in Part...97 of this chapter..."

IOW, when flying an approach with step-down fixes and step-down prescribed minimum altitudes, while on one of those segments you may not descend below the prescribed altitude. The MDA doesn't apply to this segment of the approach procedure. The rule regarding descent below MDA doesn't apply to this segment of the approach procedure because in this segment there is no MDA.

Ed Guthrie

 

[poadeleted20]

In addition to Ed's other well-taken points, it seems to me there's an approach out in LA or San Diego in which at least one step-down fix is there to keep you above other IFR traffic. In that case, descending below it would compromise IFR separation and create a "deal." So I'm 100% with those who say "no descent below a step-down fix." And for circling approaches in general, beware, beware, any attempt to leave MDA until you're SURE you are in a position to make a normal descent to the landing zone, especially in low vis or at night. That's why some (many? most?) major air carriers prohibit circling approaches at night.

 

[bbchien]

The above answer appears to ignore the second requirement of 91.175(c)(1)--"...at a normal rate of descent using normal maneuvers...". If an aircraft is below MDA it should be descending at a normal rate to a landing point. If the aircraft descends below MDA, levels off, and continues towards the intended landing point the aircraft obviously isn't in a position to use a normal descent rate because otherwise, to use that descent rate, the aircraft would need to continue descending.



The key is meeting all conditions:

1. Continuously in position to land
2. A normal rate of descent
3. Normal maneuvers

If the aircraft will violate any of those three conditions it should not be below MDA.

Ed Guthrie

The problem at ASE is, there is no such thing as a "normal rate of descent" see my previous post under "Cleared for the approach" about ASE.

http://www.pilotsofamerica.com/showthread.php?t=364

 

[spiderweb]

Thanks, guys!

 

[Alan]

Here's one you often get at Simcom. Mandatory altitudes at MARYB and at BRICE to accomodate traffic in to MCO (Orlando Intl).

http://download.aopa.org/iap/20050317/SE-3/orl_loc_bc_rwy_25.pdf

A good one to discuss would be the missed on the ILS 7 at ORL.

http://download.aopa.org/iap/20050317/SE-3/orl_ils_or_loc_rwy_07.pdf

 

[bbchien]

Yeow, Alan. Do you think the "descent to 1200 may be required when executing an early missed approach" is for ORL international's traffic?

 

[wsuffa]

Yeow, Alan. Do you think the "descent to 1200 may be required when executing an early missed approach" is for ORL international's traffic?

I'd say yes.

Take a look at the Rwy 17L approach at MCO. FAF at 1500 not too far south of the ORL approach - and a note that the altitude of 1600 may be assigned by ATC up to 13.4 DME north of MCO.

 

[Alan]

Yeow, Alan. Do you think the "descent to 1200 may be required when executing an early missed approach" is for ORL international's traffic?

Yep. So, if you goof up the approach and get full scale deflection while above 1200, you still gotta go down while trying to find the first waypoint on the missed. At leat the land is flat in FL .