night circling

[MaxFL360]

Just hoping someone could clear this up. You are circling at night at an aerodrome with 2 perpendicular Rwys, only one of the Rwys us lit and the other is impossible to see. Does the size of the circling area change compared to day operations due to one of the thresholds not being in sight?

[Captain Nomad]

Circling areas are based on the physical characteristics of the airport, runway layout compared with turning radius and manoeuvring room required for aircraft of various performance speed categories. The terrain within those circling areas is then surveyed and minima calculated accordingly. The physical characteristics of the airport do not change just because it is night, nor do the position of the obstacles so I would say 'no,' the circling area does not change based on runway lighting.

[manymak]

Circling areas are based on threshold position from each USEABLE runway. So if the runway is unusable at night due lighting then you cannot use it for the sake circling area requirements.

From jepp terminal
NOTE 3: The circling area is determined by drawing an arc centered on the threshold of each
usable runway and joining these arcs by tangents. The radii are 1.68 NM (3111m) for Category A;
2.66 NM (4926m) for Category B; 4.2 NM (7778m) for Category C; 5.28 NM (9779m) for Category
D; and 6.94 NM (12,853m) for Category E. Runways less than 1000 meters long are not considered
usable for Categories C, D and E.

[Capt Fathom]

The Circling Minimas are published on the charts. If there is a Circling Restriction, it is stated on the chart.

I don't recall seeing any that are dependant on runway lighting!

[dodo whirlygig]

"The Circling Minimas are published on the charts. If there is a Circling Restriction, it is stated on the chart.
I don't recall seeing any that are dependant on runway lighting! "


He's talking about the circling area, not the circling minimas.


Manymak has nailed it.

[Derfred]

The usable runway interpretation makes sense, but why the question? Why would you want to widen your downwind leg beyond a circling area based on the thresholds of the runway in use?

Unless some hero checkie has come up with this question just to annoy people...

[Captain Nomad]

Given the first post, I think the question/concern is actually with a non-lit perpendicular runway which when used in calculating the circling area, would allow a greater distance from the lit runway when circling at night (when on downwind for example). Is this a problem? If you are maintaining the appropriate MDA, abiding by the appropriate Perf Cat speed limits and any 'no circling' restrictions there will be no problem as the obstacles and runways haven't moved just because there are no lights on the cross-runway!

The reference stating 'usable' runway for calculation is followed by a statement expressly stating that runways less than 1000m are not "considered usable" for Cat C,D & E. That should be a big hint as to what is being used to define 'usable' (ie. runway as appropriate to aircraft Perf Cat - no mention of runway lights).

[ravan]

Surely a circling area for an instrument approach would be based on an 'Instrument Runwy' as defined at AIP Gen 2.2.

Instrument Runway: One of the following types of runways intended for the operation of aircraft using instrument approach procedures:
a. Non-precision approach runway. An instrument runway served by visual aids and a non-visual aid providing at least directional guidance adequate for a straight-in approach.

For night the 'visual aid' should be the runway lighting shouldn't it? If the crossing runway is unlit at night then it doesn't qualify as an instrument runway.

[luckyluke]

I would have though the easiest way to answer the question would be to find such an airport, look at the circling minimas/restrictions and see if there is any difference from day to night?

[The Green Goblin]

The circling area is based on the runway threshold you intend to land on. So if you have the ability to draw a ring on your GPS or FMS, it's the simplest way to keep you safe.

Pretty simple.

PS who circles these days anyway? :P

[MakeItHappenCaptain]

So how do you see the end of a non-lit runway at night to judge if you are within the prescribed area?:confused:

+1 for MM. The AIP (besides, as already mentioned, specifying useable runway), also references visual contact on many occasions. How can you use a runway you can't see?!?

[MaxFL360]

Not saying you are going to use that particular rwy, in calculating the circling area you draw arcs from each threshold out to the prescribed distance for your category. Those arcs apply even to the thresholds of runways you do not intend to land on.

[MakeItHappenCaptain]

AIP ENR 1.5 Para 1.7
Note 3
The circling area is determined by drawing an arc centred on the threshold of each usable runway and joining these arcs by tangents.
Repeat of Manymak's quote, just with AIP ref.

Comes down to whether an unlit runway is useable at night.

No argument that the circling minimum covers the area of all runways, but again, if you are conducting a visual maneouvre (which circling is), how can you be visual with an unlit feature at night?

[The Green Goblin]

The non lit runway has nothing to do with it. The circling area is based on the runway threshhold you intend to land on. IE the one with the lights :)

[as fragged]

Is this not being overthought?
The circling area is designed to give a minimum terrain clearance, so making it bigger by including a day only runway will only, potentially make the circling height higher than if was excluded (at night).
So, I reckon any usable runway (even unlit) defines the area. Simply, there is only one mda and one area and it has to cater for the most limiting scenario, which would be circling to that day only runway.
The fact you don't use the 'extra' circling area at night just means the circling area that you do use is just slightly higher than it would be otherwise.
Af

[Capn Bloggs]

How can you use a runway you can't see?!?
Look at your aerodrome chart, if the unlit runway pokes out 1/2nm in the direction of your downwind, the circling area by that amount away from the lit runway.

Is this not being overthought?
Yes... err no :)

[Compylot]

Gentlemen... may I once again congratulate you all for your robust discussions regarding the circling area dimensions of an impossible to see, unusable, unlit runway at night.

When I was but a student pilot, wearing my crisp white epaulette shirt (which I had meticulously ironed the week before but sans the one bar I so desperately craved), I was often tasked (and extremely honored!) with providing my instructor with his instant coffee before we commenced our preflight briefing.

Winding my way through the back passages of my flying school, past the rows of pictures depicting aircraft like the mighty Spitfire emerging from a stormy cloud, a shiny P51 Mustang or a B-17 about to touch down on only two wheels all battered and bruised from the intense flack over wartime Germany, I would burst into the tea room and often surprise a group of instructors huddled together, conversing in hushed tones as they clutched their coffee cups, no doubt debating in animated terms some aspect of their lives as professional aviators.

I've often wondered in the years to come, what it was these gods of aviation pondered amongst themselves.

Thank you gentlemen, now I know.

[Captain Nomad]

Compylot, thank you for your valuable contribution as always. :rolleyes:

The day you stop learning in this game is the day you die.

One only has to look at accident investigations to see that often the biggest of consequences start with the smallest of things...

“For want of a nail, the shoe was lost.
For want of a shoe, the horse was lost.
For want of a horse, the rider was lost.
For want of a rider, the battle was lost.
For want of a battle, the kingdom was lost,
And all for the want of a horseshoe nail.”

If you don't appreciate that you can find another forum to frequent and share your insights... :ugh:

[ivan ellerbai]

The non lit runway has nothing to do with it. The circling area is based on the runway threshhold you intend to land on.

Err, don't think so Goblin!!!!

Refer to MIHC's post.

[Tinstaafl]

Does the approach chart show different circling MDA for day & night?

If not, I'd suggest the circling area under consideration is the same (but still the issue of how to keep within the area if you can't see the unlit runway). If different then I'd be very careful about staying with the lit runways' arcs & tangents.

[alphacentauri]

Some things to consider...

1. Circling areas are constructed for each category depending on what useable runway you have and runway lighting is not considered.

2. The resulting area would always be more conservative, then if you only considered the runways you could use at night.

So if you get to an airfield and one of the runways has no lighting, then you circle based on the runway you can use. The circling area you end up with is contained inside the one you have been protected for (the all runways scenario).

So, to answer the question. The instrument procedure circling area has not changed. The area you can use has changed...because as many rightly pointed out how do you circle to a runway you cannot see.

Alpha

[The Green Goblin]

Yes ivan, that is correct. However if the unlit runway doesn't have an instrument approach or any lighting for that matter, it is an unusable runway and doesn't exist for your intended operation.

If you're 4.2nm North of say runway 18 at 400 agl when 27 is your intended runway and is the only runway lit at night.....you're pretty bloody stupid.

I've always based the circling area on the runway threshhold I am landing on. I'm still here.

[mcgrath50]

I've always based the circling area on the runway threshhold I am landing on. I'm still here.

Nailed the difference between what is legal and what is sensible and practical.

[Captain Nomad]

From CAAP 178-1(2) 8.3.4 "What is the circling area?"

The circling area is an area bounded by arcs drawn from the runway ends within which obstacle protection at the circling MDA of not less than 300FT for Category A/B and 400FT for Category C/D is provided. The size of the circling area is based on the maximum circling IAS permitted for each aircraft Category. In order to maintain obstacle protection the aircraft must be maintained within the circling area by visual reference to the runway. The maximum circling speeds are published in PANS-OPS and reproduced in the Australian AIP in AIP ENR 1.5, Section 1.16 Table 1.1

Category
KIAS
A
100
B
135
C
180
D
205


The question being asked was: "Does the size of the circling area change compared to day operations" - the answer is clearly 'no'

However, in practical application the only way to ensure that you are within the circling area by night is to reference lit runways. The above reference clearly combines the description of theoretical calculation of circling areas with the practical application of how to fly it.

I think we are starting to overthink it... :bored:

[noclue]

d. by night or day, while complying with a., b. and c. and from a position within the circling area on the downwind, base or final leg of the landing traffic pattern at an altitude not less than the MDA, can complete a continuous descent to the landing threshold using rates of descent and flight maneuvers which are normal for the aircraft type and, during this descent, main-tains 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

Circling area dimentions dont change between day or night, provided the visibility is sufficient, and you can still see the landing runway environment

[Compylot]

Compylot, thank you for your valuable contribution as always. :rolleyes:

The day you stop learning in this game is the day you die.

One only has to look at accident investigations to see that often the biggest of consequences start with the smallest of things...

“For want of a nail, the shoe was lost.
For want of a shoe, the horse was lost.
For want of a horse, the rider was lost.
For want of a rider, the battle was lost.
For want of a battle, the kingdom was lost,
And all for the want of a horseshoe nail.”

If you don't appreciate that you can find another forum to frequent and share your insights... :ugh:

Thank you Captain for your quotes about nails, horses, kingdoms and shoes and riders in battle, :confused:

What about runway behind and fuel on board etc?

It's easy to pretend that you are smarter than the middling intelligence you project by hiding behind fluffy quotes and threats of crashing and burning unless we enter useless debate.

My favorite quote, and you said it..

I think we are starting to overthink it... :bored:

:rolleyes:

[Captain Nomad]

Compylot, given you were confused by my last post I wasn't going to reply but I couldn't let this go by:

unless we enter useless debate.


If you understand what has been discussed I think you will find that it wasn't a useless debate.

My last advice to you is that there is no such thing as a silly question. Ridicule as a response to what you perceive to be such only shows immaturity and a lack of appreciation of the gravity of small things in aviation...

[ivan ellerbai]

No, Goblin, you've got it wrong.


The circling area, in the case of a single runway, is based on two thresholds ("bounded by arcs drawn from the runway ends within which ....... ") not just one as you state - i.e "the circling area is based on the runway threshold you intend to land on. "


Nothing wrong with your practise, conservatism is a healthy attribute in aviation, but the circling area is not based on a single threshold in the case of a single runway. Unless you're suggesting, as per your example, that Rwy27 is usable but Rwy 09 isn't!!!

[Compylot]

Compylot, given you were confused by my last post I wasn't going to reply but I couldn't let this go by:

Quote:
unless we enter useless debate.
If you understand what has been discussed I think you will find that it wasn't a useless debate.

My last advice to you is that there is no such thing as a silly question. Ridicule as a response to what you perceive to be such only shows immaturity and a lack of appreciation of the gravity of small things in aviation...

That's just wonderful advice, and yes, I am still confused by your last post..

Please explain to me again about riders and horses and the want of a horseshoe nail?

I'm still calling bull**** on your righteous quotes, and just because I ridicule your response doesn't mean I'll end up a smoking hole in the ground...

[Mach E Avelli]

:*Compylot, those "gods of aviation" huddled together in the instructor room were probably conversing in such hushed tones to avoid being overheard about how they would love to strangle certain smart arse students who reckoned to know more than their instructor. Also they would have been pondering questions likely to be asked by the only true gods in aviation, i.e. the airline selection committee.
Questions such as posed here.
Answered admirably by some contributors who I suspect know more than either you or I about the particular subject.

Also, any pilot who does not periodically contemplate the potential to end up a smoking hole in the ground is great bait for old mate fate.

[swh]

Usable runway refers to a runway suitable for that type, the example ICAO use is an airport with crossing runways, one only suitable (usable) by Cat A, and a longer usable for Cat E. The Cat E circling area is only based upon the long runway, however due to the size of the arcs, it is actually larger than the Cat A which is based upon all runways. They do not change day or night, any runway I guess could have portable lighting.

From PAN OPS

The circling approach contains the visual phase of flight after completing an instrument approach, to bring an aircraft into position for landing on a runway that for operational reasons is not suitably located for straight-in approach. In addition, when the final approach track alignment or the descent gradient does not meet the criteria for a straight-in landing, only a circling approach shall be authorized and the track alignment should ideally be made to the centre of the landing area. When necessary, the final approach track may be aligned to pass over some portion of the usable landing surface. In exceptional cases, it may be aligned beyond the aerodrome boundary, but in no case beyond 1.9 km (1.0 NM) from the usable landing surface (see Figure I-4-5-2).