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....

Thanks

https://cimg5.ibsrv.net/gimg/pprune....941897616b.jpg
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!

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.

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.

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.

BoeingDriver99

May I ask what visibility you had set?

Suitable circling distance is somewhat dependent on the visibility available.

BoeingDriver99

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.

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

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...

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.

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

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

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

Miles Magister

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

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.

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.

Circling may be limited to VMC only or captain only.

We haven’t banned them yet but I can’t 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.

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.

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.

You have to remember that a circling approach is a part of an instrument approach where the final part can not be completed without maintaining visual reference with the runway.

No two circling approaches are the same.

Many variables are considered.
Runway layout
Final Approach Track
Wind speed and
Weather conditions

If you perform a circling approach and you do not stick to the obstacle area, you risk descending into an obstacle.

I dunno....have a look at the chart.
Also, what's the circling minima for Cat D?
That may elude to what's beyond 4.2

Huh… you make an interesting point Scratcher of Butts. If I elect to use a higher minima, using Caf D or Cat E, I’m higher up, need better visibility but my safe area just got a lot larger. So how can that mean using Cat C at 4.2 is safe and Cat D at 5.28 is also safe but a few hundred feet higher?

Hey Mongo,
I agree that circling approaches are just too risky in the real world BUT they are excellent sim training.
A plus is that, one day, you might to do one for real at some crappy ETOPS diversion port. How good would it be to have done one in the sim not too long ago?

Agree whole-heartedly.
Another thing. In marginal visibility such as heavy rain that obscures forward vision or at night, it is good airmanship to stay at or above the circling MDA and don't descend below the circling MDA until you you are aligned within the takeoff splay on final.

Aircraft have crashed into terrain because they have commenced descent on early base leg of the circling approach. Charts do not always show the position of the critical obstacle that determines the MDA.

The moment you start to descend below the published MDA whether early on base leg or early final, you are entirely responsible for your own terrain or obstacle clearance - especially at night where you cannot see the terrain below you. Daytime may be different because you can see the ground and judge your own legal terrain clearance.

The Pusan Air China crash photo illustrates why. A straight in approach is not possible in the 18 Runways. Fifteen knots tailwinds are acceptable at Pusan, but in the summer when the sea breeze picks up mid afternoon, the circling approach is needed. It's written to TERPS standards, which is what caught out Air China as they didn't appreciate the different circling radiai between TERPS and PANSOPS. Korea has now moved to PANSOPs - except Pusan. I haven't been there for about 3 years now and I understand there is a RNP(AR) approach for those cleared to do it, now which is far safer.

The Banjo

Why bother with DME Arc?
Why bother with VOR approach?
Why bother with NDB approach?

Dan Winterland

There isn't an RNP AR in the public database to either 18.

Centaurus

There's nothing like early descent/late descent or different in day or night. There is only one position for descent and pilot cannot play with it. If visibility is a problem then it should not be continued. Below from JAR OPS:
A descent below MDA/H should not be initiated until the threshold of the runway to be used has been identified and the aeroplane is in a position to continue with a normal rate of descent and land within the touchdown zone.

A320 Glider

I flew one of our 777s recently and it didn’t have ADF fitted at all, so NDB approaches were off the menu anyway.

RNP approaches are demonstrably safer and usually will have lower minima compared with traditional NPAs = better chance of success. Yes, VOR/NDB are a great skills and CRM exercise in the sim but as they get rarer and rarer on the line, you get to the point where it would be better to stop flying them and use the time available to train something more relevant. The incident/accident statistics on NPAs are not good and it’s getting close to the point we should be calling time on them, now we have a viable (and better) alternative.

mustafagander

I agree somewhat on the "practice" topic, but it is FAR from excellent. I would even call it negative training as doing circling training in a sim created many situations that in real life would demand a go-around, yet we continued because we knew it was related to the simulator visuals that were unusable. Visual procedures in a sim? Nah.

I’ll agree with BraceBrace that sims are wholly unsuited to the majority of visual manoeuvres.

Yes, that’s a good point. If you a) can’t realistically train circling close to limits in the sim (which I agree with as if you start to use electronic aids and/or prompting from the back as opposed to looking out of the window, the mission has failed) and b) there is very little to no exposure on the line, logically you should be calling the whole thing into question.

We don’t circle in the USA due Ops Spec but can elsewhere, with 1,000’/minima. I used to do quite a bit when flying shorthaul in low-tech aircraft but now with an FMC/iPad full of RNP approaches, I haven’t needed to for a very long time. The guys I fly with are very likely in the same position, so if it was at all marginal, somewhere else with ILS/RNP would be looking much more attractive...

In the end it all comes down to risks vs benefits assessments. Is it worth for an operator to legally allow circling approaches when its pilots never have the chance to fly the maneuver in the sim or on the line considering the network structure ?
Some might argue it is better to leave an extra open option considering the fact that nobody would end up flying a circling approach if better options are available... but in that case some form of consistent training is required at least in the sim. It is not acceptable in my opinion to allow such a basic flight maneuver (in the end that's what a circling is - it becomes tricky only on a large transport airplane) with no recurrent training whatsoever.

BraceBrace

I was in the sim a month ago (A320) with an instructor operating the sim and another in the right seat. I wanted to video the PFD and ND during a circling approach. I prepared a simulated circling dialogue [PF, PM, ATC) to a field our company most likely would circle at. (KBZN) The dialogue consisted of flying the approach, commencing the circle, being required to go missed on short final (due to AC off runway) and flying published missed.

It is true, the visual did not allow for a good visually flown offset nor an appropriate descent to the runway. However setting the box up, flying the maneuver, and most importantly going missed was good training. It was an illuminating experience for the three of us.

Simulator training may not be appropriate but what we’re doing now, which is nothing, is wrong. A circle is treated as a normal maneuver, more normal than an engine failure on takeoff, yet a pilot, at least at our company, may not circle in his or her entire career. The company and ATC want to keep a circle as an option to be used as a last resort to get into an airfield.

Fine, then pilots should demand appropriate, effective, and recurrent circling training.

Never a truer word. In Australia there are airline pilots who are have difficulty conducting a normal circuit in perfect conditions. Judging the base and turn on to final when hand flying is apparently a tricky situation to them. In order to be stable by definition they prefer to always be radar vectored (if available) to final.

Not only that but some operators in OZ require their pilots to have landing flap selected late on the downwind leg where a circuit is being carried out, because the pilots are so apprehensive of being unstable on final that the company SOP now requires them to be stable for landing before turning base with all landing checks complete. Any fuel savings made in the cruise are shot. Vref plus additives downwind means the aircraft is being flown slower than some general aviation aircraft.

One cannot blame the pilots since by regulation they are required to follow company SOP. Presumably there must have been a few QAR reports of last minute unstable approaches from circuits so the chiefs fix that by making it SOP to be stable for landing while on late downwind. A bird strike in an engine at that point (landing flap down in level flight) would require some fancy footwork. Bet that is not practiced in the simulator..
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A company like Ryanair effectively adds circling training on regular basis as far as I know (maybe Ryanair pilots can confirm). When I was on an intercontinental network, we did circling training as some of our alternates had nothing but circling to get in. Even though we were flying ETOPS flights (Kangerlussuaq comes to my mind) it's wasn't a result of solely ETOPS alternates. We did a full emergency circle to land into Tabriz in the simulator and that worked out fine... with all the technology the aircraft provided us. And that's the goal of training I guess.

And I think that to me is the most important question: do we need it? On the network I fly currently on, I don't see the need for circling. From a "threat" perspective I think the idea of "it's a threat" is more safe than training hard and making pilots believe it becomes another standard thing. Because it is not the same safety level, it is pretty old school - based on visual clues. There are other issues to tackle in training. The goal of our job is to fly from A to B in the safest/economical best possible way.

So if operations need it, yes, train, give pilots the opportunity on a regular basis. If operations don't need it... I would avoid the simulator hassle. Because it could be very enlightning yes, but also leading to a lot of avoidable confusion and discussions.

When I was at Ryanair a circling approach was required as part of every LPC/OPC. In some bases, especially in Italy, circling approaches were a regular event and we were very swept up at flying them.

They were generally flown in VMC and ceilings well above circling minima, Though Pisa is the one I recall being most often flown at night and in crappy weather. By contrast my current employer has a minima of 1000’ aal for all circling approaches that overrides whatever is on the plate if lower. Different route networks, different policy development processes and choices.

If not current or confident, in A320 you can sequence the plan to RW threshold and the yoyo will become your glide slope.