night circling
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
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
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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.
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.
I've always based the circling area on the runway threshhold I am landing on. I'm still here.
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From CAAP 178-1(2) 8.3.4 "What is the circling area?"
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...
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
Category
KIAS
A
100
B
135
C
180
D
205
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...
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
Circling area dimentions dont change between day or night, provided the visibility is sufficient, and you can still see the landing runway environment
Compylot, thank you for your valuable contribution as always. 
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...
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...
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...
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Compylot, given you were confused by my last post I wasn't going to reply but I couldn't let this go by:
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...
unless we enter 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...
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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!!!
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, 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...
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...
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...
Last edited by Compylot; 12th Feb 2015 at 13:03.
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.
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).
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).
