Circling at night - airmanship aspects

[Hudson]

In a Seminole the other night the pilot was doing a circling approach where the MDA was 1500 ft for sea level airport. It was very dark and although the runway was in sight from his position two miles wide on downwind, the vis was such that he could not see the terrain below or ahead in the dark. He commenced descent from the circling MDA at the upwind end of the runway and arrived abeam the landing end at 1000 ft (500 ft below the circling MDA). He proceeded downwind and started his base turn at 900 ft (600 ft below the MDA). He descended on base and on lining up was 600 ft when he intercepted the T-VASIS.

Apparently some pilots interpret CASA rules (AIP) to mean that an aircraft could descend below the circling MDA at any time to suit the descent profile, even if this meant starting the descent below the night circling MDA at the beginning of the downwind leg. Even if the position of the controlling obstacle was unknown to the pilot. What is the point of publishing a circling MDA in that case?

This sounds dodgy to me. It means that if you are circling at an unfamiliar airport at night where its as black as the inside of a cow - and the published MDA is inconveniently high, then even though you cannot see the ground below to guarantee 400 ft clearance above obstacles (but you can see the runway way out to one side), the "rules" allow you to descend at your discretion below the MDA on downwind and base in order to allow a three degree profile which you had to judge without glide slope guidance. Is this really true?

[halas]

Yes.

l understand where you are coming from, as it appears rather grey in some areas.

As long as you clear all known obstacles by the required height clearance for your catagory of aircraft you can start a desent to intercept a 3 degree slope for the runway from a position that does that in the circuit.

If you remain at circling altitude until on final, and remain within the circling area, particularly in the example you gave, then you would never get in using a reasonable desent profile/rate.

If the airport in question had a conveniently located DME, this makes working a profile out easy, and accurate as long as you have the runway in sight and keep good situational awareness.

halas

[The Stooge]

Isnt it a requirement for visual circling to be insight of ground or water. Sure there are other requirements as well but if you dont meet them all wouldnt you nik off out of there. I really dont see too much of a problem here as the MDA was 1500 and then you hold that till your circling area which for a PA44 I guess is 2.66 nm and then as the rules say you intercept a normal circuit profile that may be on base that may be on downwind. I think that the idea of the rule is that you cant decend below a normal profile ie: 3 to 1. If 1500 puts you to high why not join upwind and conform to a normal circuit and use the 30 20 30 second rule which will always keep you in your circling area and whats more flying a normal circuit pattern.

[Angle of Attack]

Yes it is quite a grey area at night but I think the general jist of descent below Mda at night is that you would maintain that 1500ft in this case to a point in the circuit where you could maintain a continuous 3 degree descent to the touchdown. In this case I suppose it would be around early/mid downwind position to commence the descent from 1500ft to the threshold, as long as you have continous visual contact with the approach end of the runway. As well as this with an airport that is unknown it is pretty much essential to study the topography around the field preflight so at least you know where the high terrain is in relation to the circuit.

[splatgothebugs]

It all sounds good, I think the key to a circling app @ night is to know the area you are going into before even attempting it.

The basic rules applied to circling minima are as follows.

Cat A min of 295ft obsticle clear and 1.68nm safety circl radius fm thr.
Cat B 295ft, 2.66nm
Cat C 394, 4.2nm

These are how the circ app is calculated when been designed. So if you come down to circ mins that is what you can expect to clear terrain by.

All that aside, your best bet is not to do a circ app by night unless you have done it @ that aerodrome by day and know where your terrain is. :ok:

[currawong]

Point is, the regs are open to interpretation/misinterpretation.

Black and white, clear and concise seems to be lacking.

If in doubt or you just plain don't like it, you can always apply for a dispensation(!!??!!)

Hope the regulator surfs here and lifts its game.

[Hudson]

Go North. ENR 1.5-7. Note 1 (a): For circling approaches, clear of cloud, in sight of the ground or water etc etc.

ENR 1.5-3 para 1.7.2 says that before commencing an instrument approach, pilots should familiarise with the location and altitude of obstacles in the circling area by studying an appropriate topographical map.

Must be an interesting exercise trying to study a topo in a 737 at night prior to doing an instrument approach followed by circling. More interesting single pilot IFR! Do the RPT high and low capacity operators supply their crews with topographical maps in case circling at night needed? I've never seen a 737 crew pull out a topo at any time prior to an instrument approach, have you?

The fatal Monarch Chieftain accident at Young was caused by the pilot trying to fly a 3 degree profile below the MDA. How does a pilot know when he is on a three degree profile if he is on the downwind or base leg with no glide slope guidance? The AIP ENR 1.5-3 advice on night circling approach technique seems downright lethal yet very few pilots seem to question it.

With black night VMC in the circuit area it is doubtful if the immediate ground below the aircraft can be seen by the pilot in order to ensure minimum required obstacle clearance - so the pilot has no business descending below the circling MDA at night until established on an obstacle free final. The Mudgee circling approach is a case in point.

If this means the aircraft cannot descend safely without an excess rate of descent on final, then the obvious answer is that the pilot should divert somewhere else.

If pilots are seriously concerned that the AIP is misleading or erroneous re descent below the MDA at night on downwind and base, then I suggest writing a few CAIR reports on the subject might alert Air Services to the dangers. Maybe!

[slice]

That 1500 ft MDA for a sea level Aerodrome would, I assume, be necessary for an obstacle/group of obstacles in one particular area in the vicinity of the Aerodrome(eg hills to west). Generally I was under the impression that such 'stand out' obstacles are put on the Approach plate. As I understand it you are under no absolute obligation during visual circling to conduct a VFR type circuit (ENR 1.5 1.7.3d aside), thus you conduct the necessary circling manouvers anywhere away from the obstacles - say possibly a teardrop manouver from over the top to keep within cat circling distances(caveats about other obstacles not on the chart still apply of course).

Any opinions ?

[TAY 611]

After seeing townsville circling for 01 off the sector A arrival by day I agree with the comments about doing it by day first.

[RaTa]

Slice

"you conduct the necessary circling manouvers anywhere away from the obstacles- say possibly a teardrop manouver from over the top...."

My opinion is, since one of the requirements is to be able to maintain visual contact with the runway or approach lights, I doubt that this would be possible on a teardrop manouver.

Having said that, to go and do a circling approach at night, at an airfield with which you are not familiar and it has obstacle problems, then you would be foolish.

[splatgothebugs]

Foolish is a nice way of saying it.

There was an article in the NZ CAA Vector mag about a year ago on this very topic. It was bloody interesting with some solid facts on circling app by day and night, however it was also damming on those who attempt cir app by night with no prior knowledge of the area.

I will go have a look for it and post it when I find it, until then if anybody else knows where to find that article post it

splat

Here are two articles on circling, both are much the same.

Go to www.caa.govt.nz then go vector publication. the date to look in is Jan/Feb 2003

and apparently the flight safety Australia mag from Sept/Oct 2001 also has an article.

Sorry there are no hyperlinks but I have no idea how to do it. :)

[Captain Sand Dune]

Always a good topic to throw around the crew room! Here’s my 2 bobs worth.

Firstly, unless there was no other alternative, I wouldn’t do it!

If there is no other way, get every bit of information available about obstacles around the airfield BEFORE you get airborne (granted, not always possible) - DAPS, ERSA, topos, recent experience of the airfield during daytime, phone calls to local operators etc.

I would not descend below MDA at night until established on final. If the MDA puts me above normal circuit height (1,000 FT AGL for most types) I would fly a slightly wider pattern (although the 2NM spacing quoted in the first post seems excessive to me) to compensate. If I still can’t descend safely without an excess RoD on final then I wouldn’t go. The type of aircraft is a big factor to consider as well. In some types it is easy and safe to quickly lose excess height in order to establish on a normal glideslope.

[TIMMEEEE]

Just as a point of interest this is probably one of the highest workload areas and potentially dangerous phases of flight - conducting a circling approach at night after an instrument approach.

This is why RPT passenger services in the USA are prohibited in doing so and must conduct a runway approach rather than a circling approach.

[Winstun]

I find it astonishing that you still come across 402 GA wanabees like Slice lacking in basic aeronautical knowledge...(maybe thats why he's still a wanabee...:rolleyes: ) For the protection of your good pax, I offer you the following:
1. Never assume
2. A circling approach is not a VFR circuit nor a teardrop maneuver..:ooh:
3. If there are significant obstacles precluding a normal 3 degree descent to threshold from the MDA, a no circling area will be prescribed for that area.
4. Circling is a visual manuever and therefore clearly VERY dangerous in low visibility and at night, where vertical and lateral path perception is difficult.
This is risky business for the best of us. In short, if you are not sure, don't do it and live another day. :ok:

[splatgothebugs]

I don't know about the USA but some places here in NZ the only app avaliable is a circling app. Whangerai and Rotorua to name a couple. :uhoh:

[OzExpat]

I've never seen a 737 crew pull out a topo at any time prior to an instrument approach, have you?
No, but they DO have Company procedures with which they are required to be familiar. In most cases, the crews also have pretty extensive local knowledge due to the sheer number of times that they use any particular aerodrome.



The Mudgee circling approach is a case in point.
I spent many years, in one of my former lives, going in and out of Mudgee at night. I'd done a lot of flight training there, so was very familiar with the place. As a result, I never had a problem there.

The key is, however, to respect the hazards. Never assume that you've cleared the relevant bit of terra firma - find ways to double check that you're clear of it before descending.



Generally I was under the impression that such 'stand out' obstacles are put on the Approach plate
Nobody is ever going to give you a guarantee on that. There is no substitute for a thorough pre-flight study of a topo chart, to find out where all the obstacles are. If you don't have a company-approved procedure, using a topo chart is a must.

Armed with that information, I see no difficulty in working out a method for safe descent below MDA. The proof of this is that I'm still alive after many years of doing that. Of course, this is more of a practicality than a legality - I'm sure that we all know places that are pitch black at night, with little hope of discerning any ground features at all.

There's a lot of them around and, if you don't know the place at all, it's a good idea to assume it's one of those "pitch black" places. In the absense of a company procedure, or a good topo chart, or local knowledge, night circling isn't a clever idea.

Stay alive out there!

[BKnut]

I see a few references to ENR 1.5.7, so I presume we are talking about Australia. Go to ENR 1.5.6. It’s perfectly clear to me what that means. If you can do NGT VFR circuits there without ‘buying the farm’ then you should have no problem with a night circling approach. Being inside your circling area at 1500’ on final would make for an interesting arrival. Without knowing where the pilot (in the first post) was, the only thing I can see wrong is. The PA 44 falls naturally into category 1 with a circling area of 1.68 nm and s/he was at 900’ turning base.

[TopperHarley]

Sometimes using the cat C or D circling area and associated MDA can help.

[slice]

Winstun - suggest you take a look at the Australian AIP ENR 1.5 -

1. When I assumed it was only in relation to the initial question posed as the nature of the obstacle was not specified. If I am wrong I stand to be corrected - that is why I assumed.

2 ENR 1.5 When I stated a 'VFR type circuit' I was articulating a shorthand for the standard traffic pattern as detailed by ENR 1.5 - 1.7.3(Note 1) with downwind/base/final legs. It most certainly is a VFR manouver if you have VFR traffic in the pattern - this occurs ocasionally with higher minima approaches (eg a C206 sliding in under the ceiling). Depending on where the NDB/VOR is in relation to the field a teardrop shaped circuit or similar manouver is vital occasionally to stay within the circling area (cat B 2.66)

3 ENR 1.5 - 1.8.1 'the sector in which the obstacles are located may be eliminated from the visual circling area. Sectors which have been eliminated from the circling are annotated No Circling'. There are some approaches that have significant obstacles that do not have no circling areas

4 In an ad-hoc charter company there are no route checking requirements outside of base checks and rating renewals. I don't have a choice (not if I wanted to keep my job anyway) about going to places at night that I have never been to before and as splatgothebugs said many places have circling approaches only. As it is an ad-hoc charter a brief overview of the terrain from a 1:1000000 WAC is all we have time to do. As a mere 'wannabe' the company I worked for previously would not brook any 'I don't want to go there tonight - I have never been there and the ceiling is quite low this evening'. I think many pilots know exactly what I am talking about. The margin of safety is greatly reduced but it is not illegal so you are expected by the company do it. No one has crashed yet so in the Owner's mind it is safe.

So in short Winnie, I think it is your aeronautical knowlege that is lacking - at least in the sense of Australian regulations and remote area flying. :}

[Winstun]

If you want a brief overview of terrain in a circling area, will let you in on a little secret...a 1:1000000 WAC ain't gonna do it for you..:rolleyes: For that matter, studying any topographical map ain't gonna help you with circling....if you plan on being that low, you have no business being there with good pax.:hmm: The dangers of a legal circling approach is not "an obstacle" per se, but the difficulty for the pilot to achieve the correct lateral and vertical profile to the runway in low visibility and/or darkness with very limited visual or instrument guidance, and associated visual perception illusions. In other words, driving it into the ground...:(

[reynoldsno1]

There are a number of circling procedures in OZ that are restricted by distance limits from the runway, including some with no DME. These seem to be designed to catch the unwary, I would have thought. So how do you judge distance from a runway at night?

[Cougar]

Hudson,
In reply to your first page post, yes we do study topos before conducting a night circling approach as discussed. Of course this is done prior to departure, NOT in the air. It is mandatory for us to carry topos for the destination and divert fields for this exact reason.

[splatgothebugs]

Slice, Winstun.

Reguardless of the Kiwi's, Ozzies or Yanks rules, circling @ night as we all know can be very dangerous. At the end of the day it comes down to common sense and plenty of pre flight planning if you are unsure.

As far as single pilot RPT's go, if you don't like it tell the ops man that your not going. If they threaten your job, tell them to fire you because when it all comes out in the wash for unfair dismissal, them, not you will come out with the bad rep.

Remember it's our job to get the pax (and ourselves) safely to the destination. If you don't think you can do it safely don't go. :ok:

[ITCZ]

Agree with splat -- winstun, dont get stuck into slice, one of the biggest problems a GA pilot has these days is lack of support from experienced, old hands. Slice, dont bite with winstun. So far the topic is interesting and helpful, lets keep it that way:ok:

My 2c worth....

1. Careful when you throw in comments like "3 degree slope" and "VFR circuit" when talking about night visual circling. They can be misleading. That is not the requirement. It also might not be the best plan.

The requirement is 'complete a continuous descent to the landing threshold using rates of descent and flight manouevres which are normal for the aircraft type.'

By normal the AIP writers dont mean 'exactly the same as a CAVOK day', I think they mean normal as in not abnormal, no diving for the runway, no steep turns just to get in!

Example:
An SOP VFR circuit in our outfit (Cat C) is basically:
Join downwind clean, level at 1500 agl
Select first stage flap when level approaching abeam downwind threshold
Start timing abeam touchdown point
Time+10s, gear down
Gear down and locked, select second stage flap
Time+40s, turn base (25deg AoB), commence descent
Established on final, select landing flap, stabilised on 3 deg slope before 500 agl etc.

Contrast this with the SOP visual circling (aka 'bad weather circuit').... same aircraft:
Configured gear down and second stage flap BEFORE reaching MDA.
Much tighter spacing for the same altitude
Slower speed and time abeam +30s for base turn has us much closer to the runway for the base turn.
THIRD stage of flap for the base turn, and use AoB of 30 (not 25) degreees. Do not exceed AoB of 30 and descent rate not >1000 fpm. Mid to late base, select landing flap.

The big difference is that you are turning base 1.5 to 2 nm from the threshold, instead of almost 4nm (big difference!), cat C needing 2.66 or less.

Still NORMAL for the type, but not the CAVOK manouevres. Still flying a downwind, base and final, but tighter spacing. The considerations are different.

Standard VFR circuits are to help set you up for a nice approach and landing, don't upset the pax, and be in a predictable point in space and time for other aircraft to see you and slot into the landing pattern, see and avoid, all that stuff.

If you are night visual circling there should be nobody near you, they should all be in the holding pattern or at the hold point. Your main concern should be how best to configure and position yourself to make a successful approach.

More flap means slower, which means tighter circuit, less track miles, better turn performance. Gear down means no embarrasing moments. But it all depends on what you are trying to achieve.

Which leads to point number 2

2. Like everything else, night visual circling should be A PLANNED MANOUEVRE. Not a bush-GA style one-size-fits-all-get-out-and-get-the-job-done-make-it-up-as-you-go-along effort. Planned. Taking into account all factors.

The cirling approach plan that works best at Canberra in a C402 will be different from a Metro attempting to circle at Dili. That is why the AIP gives you some latitude as to how to go about it. Neither would look like a VFR circuit.

Splat is right. Presumably a good C402 pilot would not leave for the job without having done a fuel plan. Why the hell would you then not have a proper plan as to how you were going to get in once you arrived there? Its the same as leaving overloaded, underfuelled or not enough IFR instruments working. Bad.

Just because an aerodrome has a circling approach, doesn't mean that everyone should do one.

You should be familiar with the location. Like, been there at least once!
You might have compared the obstacles on the charts to the obstacles you spotted when you arrived and departed on CAVOK days.
You might have formulated a plan as to how you, knowing YOUR personal abilities and your aircraft, would attempt a circling approach for all runways at that location, should it ever be necessary.
You would consider aircraft config, company requirements, AFM limitations, all that stuff.
You might have chatted about your thoughts with other, preferably more experienced, pilots.
You might have had a practice go at your plan the next time you flew there on a nice day and the time pressure allowed.
Or even tried it on your pirated copy of MS FS2004 with a C172/Kingair/downloaded C402 on your home computer to see how it looked.


Like I said, my 2c worth

[slice]

ITCZ & splatbugs - don't get me wrong, a careful plan with common sense is vital - it is just that the company didn't provide anything other than WACS - fairly useless. The whole organization ran on a 'penny-wise - pound foolish' mentality providing the bare minimum of resources to pilots. Common in Oz GA.:oh:

[OZBUSDRIVER]

For information of anyone who is interested. Geoscience Australia produce a 2 CD set of the entire series of NATMAP 1:250000 topo for the complete continent and near islands of OZ. Cost is $99.00 plus a little for postage. Comes with a useful search engine for either place name lat-long grid co-ords or map sheet.
Maps can be printed from the software resulting in a small 10 nm grid or using screen capture and a paint program an accurate A4 size map can be produced in 1:250000 scale. Very handy on office PC or laptop. I use it for my PPL nav flights, like having a VTC for YOLA .

Hope this link works

http://www.ga.gov.au/nmd/products/maps/raster250k/

Regards

Mark