night circling
Thread Starter
Join Date: Aug 2014
Location: Australia
Age: 34
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
night circling
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?
Join Date: Jun 2001
Location: Enroute from Dagobah to Tatooine...!
Posts: 791
Likes: 0
Received 1 Like
on
1 Post
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.
Join Date: Dec 2008
Location: Australia
Posts: 120
Likes: 0
Received 0 Likes
on
0 Posts
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
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.
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.
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!
I don't recall seeing any that are dependant on runway lighting!
Join Date: May 2010
Location: world capital of the world
Posts: 95
Likes: 0
Received 0 Likes
on
0 Posts
"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.
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.
Join Date: Jun 2006
Location: Brisbane
Posts: 265
Likes: 0
Received 0 Likes
on
0 Posts
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...
Unless some hero checkie has come up with this question just to annoy people...
Join Date: Jun 2001
Location: Enroute from Dagobah to Tatooine...!
Posts: 791
Likes: 0
Received 1 Like
on
1 Post
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).
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).
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.
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.
Join Date: Dec 2007
Location: nz
Age: 38
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
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 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
Pretty simple.
PS who circles these days anyway? :P
So how do you see the end of a non-lit runway at night to judge if you are within the prescribed area?
+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?!?
+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?!?
Thread Starter
Join Date: Aug 2014
Location: Australia
Age: 34
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
night circling
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.
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.
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.
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?
Join Date: Sep 2011
Location: Oz
Age: 49
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
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
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
Last edited by as fragged; 10th Feb 2015 at 09:44.
How can you use a runway you can't see?!?
Is this not being overthought?
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.
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.
Join Date: Jun 2001
Location: Enroute from Dagobah to Tatooine...!
Posts: 791
Likes: 0
Received 1 Like
on
1 Post
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...
Join Date: Jul 2007
Location: Australia
Age: 73
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
The non lit runway has nothing to do with it. The circling area is based on the runway threshhold you intend to land on.
Refer to MIHC's post.
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.
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.