visual circling off an instrument approach
Originally Posted by Monopole
The conditions specified for circling are on the chart. In the case of Johnny_56 example it is x.x vis and 1600'. Just because you are allowed to decend to the OCA in day, does not mean you are allowed to do so and circle in conditions less then the circling minima. The circling minima is 1600' and the cloud base is 1350' in this example.
Originally Posted by Jepp Terminal 3.13.3
Note 2. The pilot should maintain the maximum practical obstacle clearance...
Despite the fact you are visual, clear of cloud and can see the runway, you're going to now conduct a missed approach and attempt the whole thing again?
The rest of us are going to circle, going as low as 300ft above obstacles (not comfortable, I know) and land on the runway we initially intended to.
The rest of us are going to circle, going as low as 300ft above obstacles (not comfortable, I know) and land on the runway we initially intended to.
What about airports like Kingaroy (only one that comes to mind, I'm sure there are plenty of others across the country)? The only approach (excluding RNAV) is the NDB rwy-16 (runway aligned). Based on some people's theories it might be impossible to use the airport if wind conditions did not allow a landing on 16.
There is a world of difference in (by day) being permitted to descend slightly below the cloud base, to ensure that you can remain visual while circling and maintaining visual obstacle clearance, and making up your own minimum cloud base based on a visual appreciation of 300 feet.
If this has failed to convince you - consider this: this only matters in two instances
- When you fail your IFR renewal by attempting to kill your examiner
- When you crash, survive, and the judge is examining what THEY think "equal to or better than those specified for circling" is!
Good luck in trying to convince the judge that the Black & White printed minima in front of him are NOT "those specified", and your made-up-on-the-day "I can see the ground" conditions are.
NB: In a jet, the question is moot, as the aircraft is configured in the landing configuration (ie landing flap) for a runway approach, and is thus not able to safely circle.
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This is a bit of a spurious question really, if you start the approach intending to ustilise a circling approach the you should NOT descend below the circling minima. Once you have tracked to the MAPT at the circling minima if you are not visual then a missed approach should be executed. If you are using a straight in runway aligned approach with a lower minima then you must be using this as conditions are suitable for a landing on that runway. In my opinion what you can't do is use the straight in minima purely as a basis to aloow descent below the circling minima knowing full well that you intend to circle.
Jepps state:
When daylight exists and obstacles can be seen, the pilot has the option of descending from MDA from any position within the circling area while maintaining an obstacle clearance not less that that require for the aircraft performance
In the case of CAT AB aircraft this is 300' (Jepp TERM 3.13.3).
So, if you are intending to circle then you must use the circling MDA and not below until you are visual, if you are then within the circling area and have to descend to maintain visual contact you MAY do so, but only during the day and maintaining the 300' clearance. If you use the straight in minima below the circling minima and consequently get visual and decide you can't land on that runway and then decide to circle using the above rule you could well find yourself with a bit of explaining to do if anything goes wrong. If this was truely a valid way of doing things then why have a circling minima during daylight operations anyway. Why not just use a minima 300' higher that the highest obstacle and be done with it. I suspect this was not the intention of this little note in JEPP's (to allow descent below the circling MDA before you are visual)
Jepps state:
When daylight exists and obstacles can be seen, the pilot has the option of descending from MDA from any position within the circling area while maintaining an obstacle clearance not less that that require for the aircraft performance
In the case of CAT AB aircraft this is 300' (Jepp TERM 3.13.3).
So, if you are intending to circle then you must use the circling MDA and not below until you are visual, if you are then within the circling area and have to descend to maintain visual contact you MAY do so, but only during the day and maintaining the 300' clearance. If you use the straight in minima below the circling minima and consequently get visual and decide you can't land on that runway and then decide to circle using the above rule you could well find yourself with a bit of explaining to do if anything goes wrong. If this was truely a valid way of doing things then why have a circling minima during daylight operations anyway. Why not just use a minima 300' higher that the highest obstacle and be done with it. I suspect this was not the intention of this little note in JEPP's (to allow descent below the circling MDA before you are visual)
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It's a tricky one.
Like a few 'regulations' out there it can be open to interpretation- obvious by the differing opinions here!
I can read the circling situation and understand both sides of the situation.
But I feel like I copped too much crap for stating what I thought could be done in another thread (unrelated) so I won't bother offering my opinion here! Too many people who know everything and what they say is the only way. (Good on ya Proon!)
I have my mind made up on what I would be doing and I'm happy to back that up when and if challenged in a real situation.
desmo, I recall reading somewhere on the reasons behind the circling vis being less than the straight in... I should go find it, makes for good conversation.
Like a few 'regulations' out there it can be open to interpretation- obvious by the differing opinions here!
I can read the circling situation and understand both sides of the situation.
But I feel like I copped too much crap for stating what I thought could be done in another thread (unrelated) so I won't bother offering my opinion here! Too many people who know everything and what they say is the only way. (Good on ya Proon!)
I have my mind made up on what I would be doing and I'm happy to back that up when and if challenged in a real situation.
eg.. consider you are making straight in approach and at the straight in MDA with sufficient visibility to circle but not land straight in...
Last edited by MyNameIsIs; 30th Jun 2010 at 12:58.
Moderator
So WHERE does one find the critical obstruction information so that we can descend below the circling minima to the magical 300' above obstructions?
As I've done in the past for running RTOW/RLW tables, ask the guy who designed the procedure. Even then, some of the design assessments are not as precise as I might desire to go off swanning around at low level in poor visibility ... but, then again, I am a fairly conservative sort of chap.
As I've done in the past for running RTOW/RLW tables, ask the guy who designed the procedure. Even then, some of the design assessments are not as precise as I might desire to go off swanning around at low level in poor visibility ... but, then again, I am a fairly conservative sort of chap.
Thanks John, I think you have helped make my point. Many pilots seem to think that they can rely on the obstructions shown on the aerodrome chart and just add 300' to the highest one.
Jeppesen Advise: Some, but not all, terrain high points and man-made structures are depicted, along with their elevation above mean sea level. THIS INFORMATION DOES NOT ASSURE CLEARANCE ABOVE OR AROUND THE TERRAIN OR MAN-MADE STRUCTURES AND MUST NOT BE RELIED ON FOR DESCENT BELOW THE MINMUM ALTITUDES DICTATED BY THE APPROACH PROCEDURE. Generally, terrain high points and man-made structures less than 400 feet above airport elevation are not depicted.
Ref: Jepp Intro 107. Their capitalisation.
So where do you find the critical obstruction to add 300' to?
Unless like John above you have access to the airport survey documents you cannot know this information and therefore it is simply best guess to add 300' to the highest point shown on the chart.
Mmmmmmmmmmm
Jeppesen Advise: Some, but not all, terrain high points and man-made structures are depicted, along with their elevation above mean sea level. THIS INFORMATION DOES NOT ASSURE CLEARANCE ABOVE OR AROUND THE TERRAIN OR MAN-MADE STRUCTURES AND MUST NOT BE RELIED ON FOR DESCENT BELOW THE MINMUM ALTITUDES DICTATED BY THE APPROACH PROCEDURE. Generally, terrain high points and man-made structures less than 400 feet above airport elevation are not depicted.
Ref: Jepp Intro 107. Their capitalisation.
So where do you find the critical obstruction to add 300' to?
Unless like John above you have access to the airport survey documents you cannot know this information and therefore it is simply best guess to add 300' to the highest point shown on the chart.
Mmmmmmmmmmm
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It's called the professional responsibility of a pilot to obey the law. If you descended below the charted circling minima while still in cloud, became visual at a lower level, and then proceeded to circle with me as a passenger, I would have very strong words with you on the ground (should we make it) and file a report
A missed approach must be executed if:
Quote:
d. a landing cannot be effected from a runway approach, unless a circling approach can be conducted in weather conditions equal to or better than those specified for circling
Quote:
d. a landing cannot be effected from a runway approach, unless a circling approach can be conducted in weather conditions equal to or better than those specified for circling
I'm now below the cloud base due to flying the intended runway-aligned approach. Cloud is no longer an issue. I have more than the required visibility, which is usually around 2.4km (Cat B). As long as I now stay out of cloud, maintain visual contact with the runway environment, stay out of the circling area and maintain a minimum of 300feet about obstacles I can now circle to land.
If the cloud or viz did not allow me to maintain visual contact with the runway there is no way I'd be circling below the circling MDA.
Thanks John, I think you have helped make my point. Many pilots seem to think that they can rely on the obstructions shown on the aerodrome chart and just add 300' to the highest one.
Icarus,
Who says you have to be 300' above a critical obstacle if you are visual and dont fly over it?
Artificial horizon,
Nothing spurious about the question except your opinion. Opinions are like assholes.. everybody has one.. Quote a reference to support your opinion !!
Checkboard,
Report what? Which law is being broken??
Which part of this do you guys not understand?
So where do you find the critical obstruction to add 300' to?
Artificial horizon,
This is a bit of a spurious question really, if you start the approach intending to ustilise a circling approach the you should NOT descend below the circling minima...In my opinion what you can't do is use the straight in minima purely as a basis to aloow descent below the circling minima knowing full well that you intend to circle.
Checkboard,
It's called the professional responsibility of a pilot to obey the law. If you descended below the charted circling minima while still in cloud, became visual at a lower level, and then proceeded to circle with me as a passenger, I would have very strong words with you on the ground (should we make it) and file a report.
When daylight exists and obstacles can be seen, the
pilot has the option of descending from MDA from any position within
the circling area while maintaining an obstacle clearance not
less than that required for the aircraft performance category.
pilot has the option of descending from MDA from any position within
the circling area while maintaining an obstacle clearance not
less than that required for the aircraft performance category.
1.7.3 During visual circling or during a NPA, descent below the MDA
may only occur when the pilot:
a. maintains the aircraft within the circling area; and
b. maintains a visibility, along the intended flight path, not less
than the minimum specified on the chart for the procedure; and
c. maintains visual contact with the landing runway environment
(ie, the runway threshold or approach lighting or other
markings identifiable with the runway);
and either
d. by night or day, while complying with a., b. and c. (at an altitude
not less than the MDA), intercepts a position on the downwind,
base or final leg of the landing traffic pattern, and, from this
position, can complete a continuous descent to the landing
threshold using rates of descent and flight manoeuvres which
are normal for the aircraft type and, during this descent, maintains
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;
or
e. in daylight only, while complying with a., b. and c., maintains visual
contact with obstacles along the intended flight path and
an obstacle clearance not less than the minimum for the aircraft
performance category until the aircraft is aligned with the landing
runway.
may only occur when the pilot:
a. maintains the aircraft within the circling area; and
b. maintains a visibility, along the intended flight path, not less
than the minimum specified on the chart for the procedure; and
c. maintains visual contact with the landing runway environment
(ie, the runway threshold or approach lighting or other
markings identifiable with the runway);
and either
d. by night or day, while complying with a., b. and c. (at an altitude
not less than the MDA), intercepts a position on the downwind,
base or final leg of the landing traffic pattern, and, from this
position, can complete a continuous descent to the landing
threshold using rates of descent and flight manoeuvres which
are normal for the aircraft type and, during this descent, maintains
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;
or
e. in daylight only, while complying with a., b. and c., maintains visual
contact with obstacles along the intended flight path and
an obstacle clearance not less than the minimum for the aircraft
performance category until the aircraft is aligned with the landing
runway.
Which part of this do you guys not understand?
Then why have a circling minima at all?
You could just fly the runway aligned approach down to its better minima, and if visual off that, circle in the day with your 300/400 feet. Are you telling me that I could fly an ILS down to visual @ 300 feet, then break off and circle (assuming 0 ground elevation and no obstacles)?
The regs in that section make a distinction between night and day for all other aspects of the visual approach and descent below the MDA. This particular reg doesn't however, strongly inferring that there isn't one. Whilst a CASA FOI certainly isn't the final authority on this, I asked this question yesterday and got the response I expected.
As the reg says, unless the landing can be affected from conditions equal to or better than the circling minima, a missed approach must be conducted. And by conditions, all conditions. Vis and cloud base. I understand that common sense suggests otherwise.
And for the love of god keep the self righteous abuse of others with a differing opinion to yourselves. I know we all like to think we are the final authority on everything aviation but its unnecessary.
You could just fly the runway aligned approach down to its better minima, and if visual off that, circle in the day with your 300/400 feet. Are you telling me that I could fly an ILS down to visual @ 300 feet, then break off and circle (assuming 0 ground elevation and no obstacles)?
The regs in that section make a distinction between night and day for all other aspects of the visual approach and descent below the MDA. This particular reg doesn't however, strongly inferring that there isn't one. Whilst a CASA FOI certainly isn't the final authority on this, I asked this question yesterday and got the response I expected.
As the reg says, unless the landing can be affected from conditions equal to or better than the circling minima, a missed approach must be conducted. And by conditions, all conditions. Vis and cloud base. I understand that common sense suggests otherwise.
And for the love of god keep the self righteous abuse of others with a differing opinion to yourselves. I know we all like to think we are the final authority on everything aviation but its unnecessary.
To throw another cat amongst the pigeons:
Think about that. If you've become visual @ the straight-in MDA (which is below the circling MDA) and decide to circle, then you technically have busted 1.7.3 as you descended below the circling MDA before becoming visual (and subsequently before meeting the requirements of the rest of the paragraph) and commencing the circling approach itself.
But if after becoming visual at the S-I MDA, I see no practical reason why you shouldn't be able to circle for another runway if you meet the rest of the requirements, afterall you are visual.
Technicalities
1.7.3 During visual circling or during a NPA, descent below the MDA may only occur when the pilot:
But if after becoming visual at the S-I MDA, I see no practical reason why you shouldn't be able to circle for another runway if you meet the rest of the requirements, afterall you are visual.
Technicalities
I'm with Ando in regards to maintaining the 300ft. If you don't have and IFR GPS ir DME then you have to eyeball a circling area...
I had about half a page written here, but I doubt it will change anyone's mind who is convinced to the opposite.
One thing I am sure of though. If any other pilot was to approach me and tell me that I was breaking the rules or to have 'words' with me would get several 'words' in return.
I had about half a page written here, but I doubt it will change anyone's mind who is convinced to the opposite.
One thing I am sure of though. If any other pilot was to approach me and tell me that I was breaking the rules or to have 'words' with me would get several 'words' in return.
Moderator
Many pilots seem to think that they can rely on the obstructions shown on the aerodrome chart and just add 300' to the highest one.
Brave (and, I think, a little foolish) pilots, indeed -
(a) not ALL relevant heights will be shown on such charts, necessarily. I can recall one or two celebrated examples where an aid box detail then overlaid the critical obstacle so it disappeared from the chart .. go figure.
(b) do consider the accuracy of any heights so identified .. if you are relying on such heights to be accurate to a foot or two, you might be in for a surprise
(c) terrain spot heights are just that and don't include surrounding vegetation .. some of those trees can be both tall and solid ... they'll win out every time over an aircraft ..
(d) if the chart design gets it right for cultural obstructions, well and good .. but the number of obstacle detail screwups we've seen in Australian charts over the years is a concern
(e) the guys who run up the designs start with available data and end up doing a series of flight checks at the relevant procedure heights. The terrain data nominated may not be a guarantee but, if you stay at circling height within the radii prescribed, you have a VERY good chance of NOT hitting anything hard, midairs notwithstanding.
(f) me, come below circling height ? Not on your Nellie... but, that's just my view. Getting in just isn't that important .. we can always come back for another looksee a bit later on. Accidents at Young come the mind ?
(g) if someone wants to use 300ft, fine, but do your OWN homework on the REAL obstacles as a due diligence exercise.
Unless like John above you have access to the airport survey documents
Getting copies of published data is not a difficult exercise and is open to any operator to do so. What I did, when considered necessary or appropriate, was actually speak with the specific procedure designer to find out what obstacle details he/she used in the design of the chart.
Brave (and, I think, a little foolish) pilots, indeed -
(a) not ALL relevant heights will be shown on such charts, necessarily. I can recall one or two celebrated examples where an aid box detail then overlaid the critical obstacle so it disappeared from the chart .. go figure.
(b) do consider the accuracy of any heights so identified .. if you are relying on such heights to be accurate to a foot or two, you might be in for a surprise
(c) terrain spot heights are just that and don't include surrounding vegetation .. some of those trees can be both tall and solid ... they'll win out every time over an aircraft ..
(d) if the chart design gets it right for cultural obstructions, well and good .. but the number of obstacle detail screwups we've seen in Australian charts over the years is a concern
(e) the guys who run up the designs start with available data and end up doing a series of flight checks at the relevant procedure heights. The terrain data nominated may not be a guarantee but, if you stay at circling height within the radii prescribed, you have a VERY good chance of NOT hitting anything hard, midairs notwithstanding.
(f) me, come below circling height ? Not on your Nellie... but, that's just my view. Getting in just isn't that important .. we can always come back for another looksee a bit later on. Accidents at Young come the mind ?
(g) if someone wants to use 300ft, fine, but do your OWN homework on the REAL obstacles as a due diligence exercise.
Unless like John above you have access to the airport survey documents
Getting copies of published data is not a difficult exercise and is open to any operator to do so. What I did, when considered necessary or appropriate, was actually speak with the specific procedure designer to find out what obstacle details he/she used in the design of the chart.
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There are rules and there’s common sense. Both don’t always line up.
In my opinion the rules give you the option to do what j3 (I’m not really a fighter pilot mate!) and Ando suggest – but would you always want to?!
AIP specifically states that the spot heights on the IALs do not necessarily indicate what’s out there. This is where research and local knowledge come in. There are three airfields into which I fly nearly every day. I reckon I know those airfields and their surrounds very well. Therefore I would be comfortable descending to 300FT above obstacles by day if I had to.
If I was operating into an unfamiliar airfield I would do some research as suggested by JT, but do you always have the time and/or the access to the information? Probably not. Therefore unless the conditions were quite clear below the cloud deck thus allowing me to see any potential obstacles in good time, I wouldn’t descend below circling MDA even by day.
In terms of the original scenario my decision would depend on my familiarity with the said airfield and whether it was day or night.
Day, and familiar with the airfield: Provided I am happy that I can meet the visibility and obstacle clearance requirements, I would continue for a circling approach.
Night, and familiar with the airfield: I can’t descend below circling MDA until on final at night, and I’m already below circling MDA. In this case I would fly the missed approach. (The Young prang is what precipitated the change in the rules for circling at night.)
Day or night and unfamiliar with the airfield: Missed approach.
And if you haven’t considered fuel for an alternate given those conditions regardless what the rules say - good luck to you!
In my opinion the rules give you the option to do what j3 (I’m not really a fighter pilot mate!) and Ando suggest – but would you always want to?!
AIP specifically states that the spot heights on the IALs do not necessarily indicate what’s out there. This is where research and local knowledge come in. There are three airfields into which I fly nearly every day. I reckon I know those airfields and their surrounds very well. Therefore I would be comfortable descending to 300FT above obstacles by day if I had to.
If I was operating into an unfamiliar airfield I would do some research as suggested by JT, but do you always have the time and/or the access to the information? Probably not. Therefore unless the conditions were quite clear below the cloud deck thus allowing me to see any potential obstacles in good time, I wouldn’t descend below circling MDA even by day.
In terms of the original scenario my decision would depend on my familiarity with the said airfield and whether it was day or night.
Day, and familiar with the airfield: Provided I am happy that I can meet the visibility and obstacle clearance requirements, I would continue for a circling approach.
Night, and familiar with the airfield: I can’t descend below circling MDA until on final at night, and I’m already below circling MDA. In this case I would fly the missed approach. (The Young prang is what precipitated the change in the rules for circling at night.)
Day or night and unfamiliar with the airfield: Missed approach.
And if you haven’t considered fuel for an alternate given those conditions regardless what the rules say - good luck to you!
Capt S D, I disagree with your statement that you can't descent below MDA at night until on final. The rules specify that at night the MDA must be maintained until the normal approach profile is intercepted. Depending on MDA that intercept can also occur on base or even downwind.
W.r.t the situation of reaching the Straight In MDA and deciding to circle instead of making a missed, I'm of the opinion that both vis & cloud must meet the circling minima for that approach to use the circling procedure - not the SI minima. If it's daytime and I can maintain at least 300' and the weather meets circling minima then I'd circle. I would also climb as much as conditions allow.
If it was at night then I'd commence the missed approach. During the missed if the circling requirements re Wx minima, MDA *and* still in sight of the approach end of the runway then I'd consider circling. Depends on why I couldn't complete the straight in approach. Was I a bit late descending so too high on final to continue or was the runway still occupied or similar?
Both cases presume there isn't a 'no circling' limitation that gets in the way. I always brief the circling procedure if I have any doubt about the approach, even for a straight in. Part of that includes considering how to change from straight in to a circling approach.
W.r.t the situation of reaching the Straight In MDA and deciding to circle instead of making a missed, I'm of the opinion that both vis & cloud must meet the circling minima for that approach to use the circling procedure - not the SI minima. If it's daytime and I can maintain at least 300' and the weather meets circling minima then I'd circle. I would also climb as much as conditions allow.
If it was at night then I'd commence the missed approach. During the missed if the circling requirements re Wx minima, MDA *and* still in sight of the approach end of the runway then I'd consider circling. Depends on why I couldn't complete the straight in approach. Was I a bit late descending so too high on final to continue or was the runway still occupied or similar?
Both cases presume there isn't a 'no circling' limitation that gets in the way. I always brief the circling procedure if I have any doubt about the approach, even for a straight in. Part of that includes considering how to change from straight in to a circling approach.
Last edited by Tinstaafl; 1st Jul 2010 at 06:29.