Circling approach
 

How do you perform a circling approach in your company... (procedure and technique)?

BD

BD,

Initial (ILS or other) APP with mid settings - Flap15 + Gear down on present type - to Circling Min.

Breakoff when field in sight 45deg R/L then fly 20sec (or time 45seconds including first turn) then downwind heading. If permitted (depends if FAA or JAA certified) use A/P to assist lookout.

Time after abeam (good for 800ft) 25secs +/- wind adjustment,

Flap 25, turn base, A/P off, Nail Glideslope, keep R/W in sight.

When final assured flap final setting (30 or 40) Vref + corrections.

This is the basic method. Variations possible for extra high downwind (Nice) or low downwind (rule of thumb - after abeam time three seconds per 100ft height.

Hope it is of use. FC.

[This message has been edited by Few Cloudy (edited 20 June 2001).]

Very reluctantly and only if there are no other alternatives.

Small variations in my company/aircraft:

We have two breakoff possible:
45¡ with 35 seconds
30¡ with 50 seconds
Time after "abeam threshold" 30 seconds, wind correction -1 second/2 knots tailwind (no headwind normally as mainreason for circling is to have the wind on the nose when on final).
Tolerance on MDA or circling altitude +0/-100

All in all a very enjoyable and challenging manoeuvre to fly (try GEN at nite with northely winds) :)

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... cut my wings and I'll die ...

Thanks for the reply

i've heard about someone using landing flap even in the downwind leg during the circling: is any one of you, out there, using this procedure? (i mean in heavy jets).

thanks

fly4fud---
With the FAA, if you tried the +0/-100' during the circling maneuver, it would be failure time.

Usually not with landing flap on downwind as you lose GPWS.

If your company will allow it, the 80/260 or 90/270 degree is a 'quick and dirty' that works well for the reciprocal of the runway you did the approach on. If you wish do do it gear down, proceed as for a normal straight in landing - ie gear down, approach flap. At circling limits, add power to maintain altitude, track down the runway centerline visually to the threshold and commence a rate one right turn to 80 degrees off your heading. Upon reaching that, crank in an immediate left rate one turn. If you've done everything right, when you hit 260 degrees of turn you're on final.
Next time you're in the sim, try it to find out if you need to use 80 or 90 degrees in the initial turn - thus 260 or 270 degrees to put you on final. For some reason, Gulfstreams needed 80/260 and Fokkers 90/270 degrees for it to work properly.

Approach flap and gear up until visual on downwind.

Only problem with 80/260 and 90/270 turns is that you are supposed to keep the runway in sight during a circling approach.

Why would anyone flying a high speed jet transport a/c even consider doing a low level BWC?...unless you want to kill yourself that is, build up your stress levels or scare the living daylights out of your pax! There is ALWAYS an alternative.

The FAA insists on maintaining the circling altitude until established on final track, which means that for a large airplane you will be out a long way on final or else you will be high on glidepath. ICAO allows descent when on the normal glide path, which usually happens on base leg. Am I right about this? The subject gets confusing.

I also believe that if you are circling you are not flying IFR any longer, but are visual. This means that visual limits apply (in sight of ground or water and clear of cloud). It seems reasonable to me that flying in and out of the cloud base makes no sense. Better to drop down a hundred feet and maintain visual.

Many of you believe that a circling approach should not be flown in a large airplane, and some even maintain that an NDB approach is not on. If you never practice them, I suppose you should not try, but for the real pilots out there (there must be a few left) don't pay those people any mind. When the weather is bad and the aids have gone down due to power failures, the circling approach might be all that is left to you. You will feel a lot better knowing that you can handle it than to be in the state of panic those 'experts' will be experiencing.
You can practice the circling/visual/non-precision approaches on line in good weather, or in the sim (ask the Instructor!) in any weather or vis you want.

A diversion might not be available to you, and even if it is, you could be faced with a worse combination of weather and approaches at the alternate, and in addition you will have minimum fuel.

This is yet another example of attempting to regulate safety. It will never work.

Boofhead--
The FAA allows descent from the circling MDA,
during normal descent to landing, ie: from base leg if that is the "normal" descent point that you would normally use, all things being normal, of course. http://www.pprune.org/ubb/NonCGI/eek.gif

411A, Jeppensen ATC chapter:

Descent below MDA(H) should not be made until:
a. visual reference has been established and can be maintained
b. the pilot has the landing threshold in sight; and
c. the required obstacle clearance can be maintained and the aircraft is in a position to carry out a landing
NOTE: The procedure does not provide protection from obstacles when the aircraft is below the OCA/H; MDA/H

All this to say that given the conditions above, this text would permit to leave the MDA even in the downwind. Remember, as stated by "boofhead", this is a visual approach procedure!

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... cut my wings and I'll die ...

fly4fud---
Yes agreed, that's what the Jeppesen manual says but, if you were to descend from say, 600 feet (MDA) on the downwind leg during an FAA type ride, the FAA inspector would have your pink slip filled out before the motion was off in the sim. Like it or not, that's the way it is, and has been for many years. CAA may well be different, of course.

Jeppesen ATC Section on Air Traffic Control US-382: Section 4 Arrival Procedures Ref 5-4-18f states:-

blah blah blah..."Pilots should remain at or above the circling altitude until the aircraft is continuously in a position from which a decent to landing on the intended runway can be made at a normal rate of decent using normal procedures.......

Basic rules apply.
1) maneuver the shortest path to the base or downwind leg as apprpriate considering existing weather conditions

2) keep the runway in sight etc

So your correct if you descend from MCA level off and then continue dscent to the landing the Feds will bust you, just as they would if you stray outside the protected area. Obviously, you are flying at an altitude that doesnt make the necessary obstacle clearance.

5-4-18 also prescribes Circling Approach Radii.

App Cat Radius
A 1.3 miles
B 1.5 miles
c 1.7 miles
D 2.3 miles
E 4.5 miles

all measured from the end of all runways (if you see what I mean)

[This message has been edited by Gspot (edited 26 June 2001).]

[This message has been edited by Gspot (edited 26 June 2001).]

Right Way Up, told ya it was "quick and dirty." :)

411A, have to agree with you. If you descended below circling limits until established on final, it was back to the dugout.

Pigboat,

I'm not sure that you have to be on final.

If your a Cat C aircraft and the Circling minimum is say 6ooFt agl then if you remain in an area prescribed by drawing intersecting circles of 1.7 miles radius from the center of the end of each runway at the airport, not just the runway you are attempting to use, and remain at 600' until the point where you can initiate a constant descent rate, then you are in protected airspace and guaranteed adequate terrain clearance. You could conceivabley be on base. http://www.pprune.org/ubb/NonCGI/confused.gif

In Oz MDA (minimum descent alt) for circling is the minimum altitude for the instrument approach in IMC.

Once visual within the circling area you can legally come down to the lower OCA (obstacle clearance alt.) if required for example to remain visual. Our AIP elaborates and specifically states that descent below MDA can occur on base or downwind if required for normal descent to the threshold.

Once established on final descent below OCA can occur to the threshold.

What I want to know is; is it legal to bump your category UP to get a bigger circling area and more comfortable approach speeds at the expense of a higher MDA and OCA? It seems to be common practice here.


[This message has been edited by daytrader (edited 27 June 2001).]

I wonder if Boofheads second name is "cowboy "?....and does he fly heavy jets professionally?...I wonder!

Sorry guys, but the issue has somewhat gone astray: my question was just how do you perform (tecnique) the circling approach in your Company. This is because my Company wants to introduce landing flap configuration during the downwind leg. So my question is how many of you,if any out there, use the landing configuration during the downwind leg.

BD

Black_Dawn - don't know the type you fly but what about the engine failure situation if you are taking landing (aka full) flap downwind?

To my mind this would be one definite reason against taking landing flap at this stage.

Nothing wrong with a circling approach if you have planned it well and are practised at it. As has been said previously, practice it in the sim first.

IMHO where a circling approach often starts to go "off the rails" at the beginning of the instrument approach. You have to ask yourself WHY you are circling? It means a) there is a significant wind blowing (otherwise you could do a straight in on the instrument approach) and b) the cloudbase/viz is relatively low (otherwise you could do a "normal" visual approach).

The wind situation means that you have to apply "unusual" wind corrections on the outbound part of the procedure and when you turn inbound your groundspeed is much higher than you are used to because a)you are probably flying the approach at higher IAS (due to config, etc.) and b) you have a tailwind!!

All this makes it all feel "unfamiliar" and then at the end of the instrument approach you then may have to fly a low level visual circuit.

Absolutely nothing wrong with all this so long as you know what you are doing!

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Daytrader,

Bear in mind a higher Category with it's larger radii might also result in higher Circling Minimums.

Black_Dawn, I think Fireflybob makes some very good points. Also do you know how much power (fuel) it takes to fly level in a fully configured aircraft and how that would affect the approach climb performance. Maybe get your dispatch guys to run the numbers for you unless you guys use an OPC (onboard Performance Computer)then you can do it yourself.

I'm going to work tomorrow I'll put the numbers in the OPC and see what the results are. I'll let you know.

Gspot

you're right about the approach climb gradient; about the fuel ,i don't think it's an issue: how many circling approaches do you make? quite an age the last one i did myself!My doubts came out when my chief said that using landing flaps on downwind, was now a common procedure in other european companies.I'm doubting about this.
So i'm asking.

BD

Circling approaches are certainly good sport in big aircraft. You both need to be well briefed about what you are going to do and how and you are going to fly the approach. Practice is certainly required which makes the latest change for LPC/OPC checks seem very strange, it is now only required once every 3 years in the sim. Anyone know if this is just us or does it apply to all JAA operators?. I know we don't so them very often but when you do it is demanding manoeuvre and I would like a crack at more often than every three years.

At the risk of opening a real can of worms, how about go-arounds from circling approaches? ie. what go-around do you fly from various stages of the approach. The CAA advice for this has changed several times in the last few years but whatever the rules say it is something you need to have a long hard think about before you shoot the approach to avoid other a/c flying the same approach (CFU for example, no help from ATC there I suspect).

Cowboy, Amos? I think it is gone already but thanks for the suggestion.

I did the FAA check ride and the examiner was adamant that I could not descend until on final. Maybe they are not up with their own regs.

As it happens I do fly big airplanes and the FAA (and comanpy limit) restricts us to 1000 feet/3 miles for circling, which is always way above the Category D minima. I therefore can descend to remain clear of cloud and still maintain terrain clearance. But can I do it legally?

But I would still consider it makes more sense to remain visual during the approach rather than fly at the circling minima if this altitude keeps me at the cloud base and unable to see where I am going.

What happened to common sense?

Black_Dawn, in the company I fly for, no need for landing flaps during the downwind. The things we have is to have the wheels out abeam, a "final check", i.e. ld flaps when turning final, and this final segment is to be minimum 30" or .5 NM for Cat C aircraft. But, landing flap can also have the advantage of reducing the turn radius, therefore enabling you to be closer to the runway and not to lose it.

Anybody able to tell me where I can find an IFR tolerance list containing those applying to MDH/A for all approaches, could'nt find it in the Jepp, but probably didn't look well enough...

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... cut my wings and I'll die ...

Gspot, the descent from MDA could be a matter of interpretation. The Canadian AIP says..."and remain at the circling MDA until a normal landing is assured." We always took that to mean intercept the final approach at the MDA.

Daytrader, I once did an IR renewal in very gusty conditions. After adding the gust factor, the inspector insisted the new airspeed would change our category from B to C, thus the higher circling limits would apply.

Max Angle, in this country, anyway, it's less a can of worms than you may think. The Canadian AIP says:
The pilot may have to conduct a missed approach after starting visual manoeuvers.
There are no standard procedures in this situation. Thus, unless the pilot is familiar with the terrain, it is recommended that:
(a) a climb be initiated;
(b) the aircraft be turned toward the center of the aerodrome; and
(c) the aircraft be established, as closely as possible, in the missed approach procedure published for the instrument approach procedure just completed.

[This message has been edited by pigboat (edited 28 June 2001).]

A few observations...

(a) re - electing to operate to the requirements for a higher category - there ought not to be any concern with this as categorisation is min speed dependent and operating to more restrictive standards should be viewed favourably by company lawyers, the Regulator, and the judge in the enquiry/action after the mishap ...

There is never any requirement which says that one MUST operate at the most critical limit - it may be a useful option, but not a prescription. Thus, to descend to the published minimum, for example by day in visual contact after a cloud break, if the circuit can be flown at a higher, more "normal" height, seems a little silly from a risk management viewpoint. This would be philosophically similar to conducting all turning operations at the limit load factor.

(b) if you elect to operate to a higher category, then it has to be all or nothing - while you get the benefit of an increased radius for circling protection there comes a downside with the attendent larger protected area - you also probably pick up some additional hard bits and this leads to the typically associated higher circling minimum altitude.

(c) be VERY, VERY wary about descending below the published minimum until on the normal approach path UNLESS you know VERY ACCURATELY what and where the obstructions are. It is very illustrative to check with the local procedures designers as to how they establish the minimum.

Unless someone actually goes out and does a survey of critical obstructions, and this is done in some cases by individual operators seeking either an alternative or just a better documented procedure, one ought to be very careful and cautious about the accuracy of the obstacle data used in routine procedure design.

The flight inspection test of the procedure (presuming that is, in fact, done) will pick up any gross errors but won't necessarily cover the brave chap stooging around at some significant height below the published minimum. It is all well and good to bandy intentions and expectations embodied in PANS-OPS or similar diagrams. However, at the end of the day, the operator or pilot who wants to predicate his actual height on the specific flightpath needs to be very sure of the specific obstacle profile.

(d) the question of a missed approach initiated from a circling approach is always contentious.

The simplest philosophy says that one turns toward the field and then tries to pick up the letdown published missed approach. This is often not so simple a matter.

I suggest that a better management procedure is that an operator, choosing to conduct (or permit) circling approaches at a specific aerodrome with other than benign surrounding terrain, ought to conduct an escape analysis similar to that which should be done for the takeoff case. After all, the two are much the same sort of thing, both from the point of problems and desired outcome.

Black Dawn:

when i was with Asiana Airlines Nov 96-Mar 98, they had us gear down flaps 25 in the B737-400/500 on the circle before abeam the runway. i think on base, we went full flaps.
so many airlines and so many proceedures i get them confused sometimes.

i do honestly think that if you check four different airlines you will find 10 different ways to do the circle.

and we did quite a few into Pohang, Taegu, Kwangju and Cheju. before going there, all the circles i did was in a sim. there it was expected often.

all other questions aside, if the chief pilot wants me to circle at flaps 25, i will if i want to work there.

on one training flight to Pohang with good weather, on the downwind to base corner i started descending to shorten my circuit and as we were surrounded by mountains on the south and east while circling to land west, we ended up getting a good scenic turn amoungst the mountains. the training captain started yelling!! "Look!! the mountains!!!" as he was pointing in front on my face. i said, "Yeah, they're beautiful aren't they?"

we never lost sight of the runway nor the mountains and landed safely.

i passed the training.

though i admit that when i re-applied there last year they said no. it may have been also because i was very vocal about all the things i thought they were doing poorly.

so i have learned to say, "yes sir. thank you very muchee!" to the man with the pen in his hand, and then fly it the way it should be when he is gone.

but don't listen to me, i are just a peelot!

My Boeing 737 manual (not a company designed one, but the manufacturer's FTM), states flap 15 and gear down for the circling approach but as the aircraft turns on to base leg take landing flap and reduce to speed to Vref plus additives. Different config if one engine inop.

The real discussion should centre on circling approaches at night and at the circling visibility limit, which could be as low as 2.4 kms.

Obviously the circling MDA is there to protect you from terrain/obstacles. On a black night you will not see the controlling obstacle, but never fear, it has been worked out for you. It could even be near base leg.

Therefore on an inky night, you are committed for safety reasons to sticking to the circling MDA until on final with runway and or VASIS in view.

If a relatively high circling MDA means that on base you would have to descend in order to ensure a stabilized approach - then stiff cheddar, you should not be carrying out a circling approach in the first place. Same thing with downwind descent.

The designers of the chart MDA couldn't care less about your problems with a stable three degree descent from the circling MDA. That is your problem, not the chart designer.

Daytime circling is another story because one assumes you can see where you are going and descend as required providing you maintain legal safe visibility (runway in sight)and minimum legal obstacle clearance.

But night is the real killer on circling approaches. You can see the runway (I hope) but it is too black around you to see that unlit deadly hilltop, with its 100ft high trees, situated somewhere in your circling area - You know it is there somewhere, but its real black outside your windscreen so you cannot see a thing except the lit runway. Certainly the chart will not necessarily display the position of the controlling obstacle. Hence the danger.

Therefore you are only safe to descend below the chart MDA when you are established on final, within the circling distance limit for your category, and runway in sight. If that puts you too high to complete a stable approach, then that is your problem.

Regardless of all the FAA/JAA/ Afghanistan CAA rules in the world, the plain fact is that at night you have no choice (if you want to live) except to stay at the charted MDA until on final.

[This message has been edited by Centaurus (edited 28 June 2001).]

A standard circling profile can't always be flown. For example when circling to Rwy 17 at UIO (elev 9213) due to rising terrain the final can be no more than 2 miles; final landing configuration and checklist must be completed, and descent started on base leg!

Glue ball. That is fine as long as the any obstacles below the MDA can be seen and avoided. Can you count on that at night? If not, then that becomes a problem for the pilot and the passengers down the back hoping for a safe trip.

Centaurus,

You said - "If a relatively high circling MDA means that on base you would have to descend in order to ensure a stabilized approach - then stiff cheddar, you should not be carrying out a circling approach in the first place. Same thing with downwind descent."

Just curious if this is a company restriction or a personal limit you impose on yourself? As someone who is just about to begin their Instrument Rating I find this a valuable discussion.

As we all know, Jepp Australia Terminal para 3.11.3 says -

"...descent below the MDA may only occur when the pilot:
(a)...within circling area...
(b)...maintains specified vis...
(c)...maintains visual contact...
(c) by night or day, while complying with a,b and c, (at an altitude not less than MDA), intercepts a position on the downwind, base or final leg of the landing traffic pattern, and from this position can complete a continuous descent to the landing threshold, ... and maintains an obstacle clearance along the flight path not less than the minimum for the aircraft performance category until the aircraft is aligned with the landing runway."

I realise that it is impossible to see an unlit obstacle at night in crappy weather, but would the quoted spot heights suffice for this? i.e. spot height + 300'.

Any input on this would be greatly appreciated.

Cheers,
TL





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"Tears, crying, wish you'd never learnt to fly. Should have taken that job at the Council."

Transition Layer,

Herein lies a few of the problems

(a) the spot heights are

(i) not without an error dependent on the accuracy of the source data used

(ii) usually are for ground level (at least in this neck of the woods) - you were going to have a stab at tree height etc. ? What about cultural development not shown ? The only way to get around this either is to use fairly recent OPMs and make local enquiries of public authorities or get out on shank's pony and have a look from the ground with a theodolite over the shoulder. The latter often has to be done with nasty aerodromes .... If access is difficult, I have even resorted to flying the local area in simulated OEI climbs to check the base data.

(b) the spot heights nominated may not be the only significant concerns in the area

(c) sometimes there is a drafting screwup. An operator with which I have an association recently found a letdown chart in which the critical obstruction was located under one of the navaid boxes - ie not shown on the plate

None of this is difficult, although it can be a right pain, but none of it is amenable to pilot decision-making on the run. Conservatism is most appropriate, especially at night, or in low visibility by day.

People may choose to view Centaurus' views as unnecessarily conservative .. but I will continue to be more comfortable in the cabin with that sort of attitude up front ...

You pays your money ... you takes your chances ...

[This message has been edited by john_tullamarine (edited 29 June 2001).]

John T,

Thanks for clearing that up mate. Actually, just after I posted I read the small note above that Jepp reference I posted which says similar things about spot heights. (para 3.11.2)

From what I can gather, maintaining MDA until on final is the most sensible option, despite what the references might say. Like many things, it seems to come down to the interpretation and decision making of the PIC.

And like you say, nothing at all wrong with being conservative up front! :)

Thanks again.

TL



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"Tears, crying, wish you'd never learnt to fly. Should have taken that job at the Council."

I'm with Centaurus and john_t.

They are one black snake. Terrain or no.
In the serious corporate world, they are just not on. No precision approach no go, at least in IMC or at night.
So what if they are approved, unless you are seriously current, up to speed and regularly shoot the particular approach, it IMHO, for all intents and purposes does not exist. Especially single pilot ops.

Airline ops with currency and disciplined SOPS are another thing, but still require a very high level of awareness.

They are no mere intelectual exercise in execution.

Pucker factor 10.

Folks,

Very interesting discussion, particularly the latter twist.

Yes, if one has the luxury of avoiding circling approaches, take the option.

However, maintaining MDA until established on finals is often creating a greater potential risk than it may be intended to avoid. For PANS-OPS players, the protected airspace is fairly large and you may well be able to use the airspace to your advantage in achieving a reasonable finals profile from MDA - provided you have and maintain adequate visibility. For TERPS players, the protected airspace is ridiculously small (compare Cat C PANS-OPS at 4.2nm with CAT C TERPS at 1.7nm!!) and rolling out on high final (or was that high high high final) may well invite the unstabilised death dive that seems to cause more accidents then flying into the ground while descending around base.

Yes, there are some difficulties in getting adequate data for procedure design but PANS-OPS does include factors for many of the issues that JT raises. We should generally remember that aircraft operate into these places by day and as part of their normal circuit operations will invariably identify obstacle issues and, more variably, report problems to the procedure designers. Thus, even if a procedure is not flight tested, you are not totally committing to the unknown.

Furthermore, ICAO requires route and aerodrome qualification for scheduled operations - specifically so that you are not taking a !!!!!load of passengers on a voyage of discovery during a circling approach at night. Charter operators face a more difficult problem, but not an insurmountable problem if one is prepared to invest the time and resources.

So, how do I manage the risk of descending at the appropriate point on the cicrling flight path? I work out where I should be at my OCH on finals (for me +400ft) and then I work back up and around the base turn to plan some gates (let's say +800ft mid base and +1200ft commencing the turn). If I commence the base turn abeam my finals roll-out point, then I should be about 1.2nm past abeam the threshold. Note that under TERPS that is as far as I can afford to go before turning!! Now I look at the circling minima and work out what I have to do to intercept that flight path.

As much as I hate them, it is the planning, practice and pucker factor that drives the discipline to get them right. But there is a big difference between respect and fear - find a way to get rid of the latter in favour of the former. And until we have straight-in approaches everywhere, circling is still going to exist and will still need to be approached professionally.

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Stay Alive,

[email protected]




[This message has been edited by 4dogs (edited 29 June 2001).]

The circling approach at UIO (Quito, Ecuador)
requires 8 km visibility, so in fact it becomes a visual approach with an MDA of 10,500' (elev 9213) and I don't believe it's authorized at night, although the Jeppesen chart doesn't say that. The airport is listed as "Special Airport Qualification."
In any case, it's a 2 mile final for Rwy 17!

Straight in GPS non precision approaches progressively will cause the problem to go away in, perhaps, the majority of locations ?