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-   -   Circling approach, what lurks beyond the circling area? (https://www.pprune.org/tech-log/640730-circling-approach-what-lurks-beyond-circling-area.html)

BoeingDriver99 28th May 2021 09:41

Circling approach, what lurks beyond the circling area?
Watched another session of poorly flown circling approaches in the sim and the crew, as is common, demonstrated a willingness to stay as close to the runway as possible throughout the maneuver thus making their job commensurately more difficult. It got me thinking, what lurks beyond the circling area? For my type it's Cat C, PANS-OPS so 4.2nm from the runway thresholds. I had a look through 8168 and it wasn't super obvious to me. What is the situation for obstacles beyond 4.2nm or whichever distance for the specific category of aircraft being flown? I would hazard a guess and say that 4.3nm does not mean certain death....


40KTSOFFOG 28th May 2021 10:08

Air China, Busan, 15/04/2020
Circling approach in poor viz. Although this was based on TERPS minima (1.7nm) it does demonstrate the dangers of straying outside limits!

FlyingStone 28th May 2021 10:36

Originally Posted by BoeingDriver99 (Post 11052882)
I would hazard a guess and say that 4.3nm does not mean certain death....

It just means that whoever designs the procedure doesn't need to take any obtacles outside of that area into account. So at 4.3nm you could have more flat terrain or Mt Everest.

Same goes for every other instrument procedure. Fly it within prescribed limits, or you're a test pilot.

snips 28th May 2021 10:43

To paraphrase 8168 "Obstruction clearance cannot be guaranteed" . Nothing precludes circling at a higher category you just have to apply that particular minima. The approach plates tend to mark the significant obstructions so you could come up with a "fudge" however
you run the risk of stepping outside of accepted practise and having to answer to the Chief Pilot/Feds/Judge etc.

oggers 28th May 2021 10:56

There is no secondary area for the circling approach area so there is zero protection if straying outside, only the hope no obstacle happens to be there.

Switchbait 28th May 2021 11:26


May I ask what visibility you had set?

Suitable circling distance is somewhat dependent on the visibility available.

Qwark 28th May 2021 11:31


The first mistake is to assume you have safety if within 4.2 NM for a CAT C aircraft. The accident in Busan is a good example. The report stated something like they suspected the crew didnt realize the IAP Chart used was designed to FAA TERPS criteria.So obstacles outside 1.7 NM are not surveyed. For International crew its essential to be aware different Regions design their instrument procedures to a variety of standards.

FlightDetent 28th May 2021 11:33

Originally Posted by BoeingDriver99 (Post 11052882)
I would hazard a guess and say that 4.3nm does not mean certain death....

Except for the cases it does, of course. Although mountains are seldom vertical.

The Banjo 28th May 2021 11:51

Why are you even bothering with circling approaches in this day and age? With straight in approaches published training time can be better utilised elsewhere. The TERPS criteria were/are being progressively changed from 1.7 to 2.7nm from 2013. It's in JEPPS General but the implimentation is not clear...

Miles Magister 28th May 2021 11:59

Snips makes a very good point. You can always uses a higher circling height. The procedure minimum for your CAT is a minimum, not a target. You can circle at whatever height you like above the minimum, including doing a normal visual circuit if weather permits. Sometimes you need to circle for reasons other than weather. Also you do not need to keep the runway in sight, just the runway environment. If you look at the visibility minima vs the the assumed r values and protected area then you can circle out of visual range of the runway when weather is on or near minima.
Also be aware of the differences between PANSOPS and TERPS as the minima and obstacle clearances are significantly different. Check the approach chart to see which criteria have been used in the procedure design. If you have not done a simple course on the differences then do one.
Those of us who are lucky enough to have been trained in the olden days and flew QGH flame out controlled descents or radar PFLs where you broke cloud at around 500' over the airfield and then flew a glide approach to whichever runway appeared out of the gloom tend to be more comfortable circling. Low level visual flying and turning in bad weather is a very definite skill all of it's own which is just not trained any more, let alone practiced and it does require a high level of skill to do safely.

The Banjo 28th May 2021 12:13

Somehow I don't think society would tolerate the RAF accident rates of the 1950s-1980s jet ops in civil aviation.

FlyingStone 28th May 2021 12:46

Originally Posted by The Banjo (Post 11052976)
Why are you even bothering with circling approaches in this day and age? With straight in approaches published training time can be better utilised elsewhere.

I'd fully agree if all airports had straight-in approaches published to all runways. Sadly, that's not the case.

aterpster 28th May 2021 13:38

TERPs now has a greater area than 1.7 n.m. for CAT C. Larger, and increases with airport elevation.

Obama57 28th May 2021 22:48

Miles Magister

O.I.C. And maybe you could tell us how to fly the range. I’m on the edge of my seat.

BoeingDriver99 29th May 2021 03:27

TIL that outside the proscribed area there is no margin guaranteed at all.

In real life I reckon I would only ever circle to land if the weather was benign but for whatever reason ATC required a different IAP and circle to land. I can think of Palermo, Sicily a few years back when they were not allowing visual approaches across all of Italy and the navaids for 07/25 were being repaired. So we had to regularly fly an NPA for 02/20 and circle to land on 07 in CAVOK, slack winds.

TukwillaFlyboy 29th May 2021 05:20

The carrier I work for has banned circling approaches.
With RNP or GNSS approaches at both ends of every runway we operate into they are redundant and , quite frankly , archaic and dangerous.
Get rid of them.

Pugilistic Animus 29th May 2021 06:02

Circling may be limited to VMC only or captain only.

FullWings 29th May 2021 06:47

We havenít banned them yet but I canít remember the last time I had to fly one. Quite a few places we go to have switched to RNAV or RNAV Visual Approaches where you might have circled in the old days.

I agree with previous posters that the risk/reward ratio is all wrong and, collectively, there has been definite skill atrophy in this area.

Nick 1 29th May 2021 09:32

This is a very informative series of presentations regarding the circling , he explain in a geometrical and a mathematical way how , if you need to meet the regulator limitation ( 25 * of bank , stabilized at 300 ft , speed according to Icao ) is impossible to remain with the runway in sight during a circling with 2400 mt of visibility .

Not in english but slides are quite clear to give an idea.

CaptainMongo 29th May 2021 14:29

Originally Posted by FullWings (Post 11053387)
We haven’t banned them yet but I can’t remember the last time I had to fly one.

Our carrier hasn’t banned them either. I’m coming to the opinion however that they should be banned. Not because circling is inherently dangerous, but because we NEVER practice the maneuver prior to the real world event.

We don’t practice them in the sim for fun or as a training requirement. The closest our pilots get to circling before actually flying a circling approach is on the ground - reading flight manual sections describing circling, classroom instruction and line operational experience briefings. That would not be allowed in any other aspect of aviation.

Our circling minimums are 1000-3 or published, whichever is higher. I know that’s not rooting around in the weeds. I also know there will be some who say that pilots should be able to fly a circle with no simulator training and maybe a pilot should be able to do that. But the reality is I don’t have confidence every one of our pilots could do that with the circling training we presently get.

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