More on huge circuits at Moorabbin/Point Cook
Guest
Posts: n/a
More on huge circuits at Moorabbin/Point Cook
May/June issue of Australian Flying Magazine has article on standard circuit patterns according to one particular MB flying school operator. The operator claims that its standard pattern is 1.8 miles wide in daytime.
At an industry/CASA meeting a few months back, this circuit recommendation was discussed, with a representive of the operator stating that at night the circuit was extended to two miles wide for safety reasons. ie Rate half turns. One contributor at the meeting claimed that the Boeing published recommended circuit width for the B737 was 1.5 miles.
If that statement is true, then why is the "standard" flying school circuit width flown at 110 knots that much wider than a 737 flown at 180 knots? Are some student pilots so incompetent nowadays that they need more airspace and time to think ahead? Deliberate wide circuits cost the students and those unfortunate pilots who are forced to follow them, a lot of extra money. No small wonder that flying schools are losing students.
At an industry/CASA meeting a few months back, this circuit recommendation was discussed, with a representive of the operator stating that at night the circuit was extended to two miles wide for safety reasons. ie Rate half turns. One contributor at the meeting claimed that the Boeing published recommended circuit width for the B737 was 1.5 miles.
If that statement is true, then why is the "standard" flying school circuit width flown at 110 knots that much wider than a 737 flown at 180 knots? Are some student pilots so incompetent nowadays that they need more airspace and time to think ahead? Deliberate wide circuits cost the students and those unfortunate pilots who are forced to follow them, a lot of extra money. No small wonder that flying schools are losing students.
1.8 miles? How can you justify that? I was under the impression that one of the ideas of flying a circuit as such was to be within easy gliding range of the runway for the longest possible time when close to the ground. I know that C210 (in all honesty, one of the most likely candidates for most brand new cpl students to move into when lucky enough to score their first job), uses somewhere around a mile of distance (nil wind) to descend around a thousand feet in a straight line. If it is heavy, the best glide speed goes up by up to ten knots. You don't need to be Einstien (spl) to work out that while a close circuit can be difficult for a student to manage in terms of speed and engine control, wouldn't it pose more of a challenge and the end result being a student "more on the ball" than the student who just drags it in from miles away (possibly citing the 3 deg ILS descent profile as the reason)? You want to teach that, then do it when the student does their CIR.
Bear the "recent" fuel starvation/exhaustion accidents (where a couple of charter a/c lost power in their respective circuits), in mind. At 1.8 miles you are having an off-airport landing in a single engine, no question. Can you afford that, mr instructor? You are, after all, the PIC!
You own the wreckage if you are proved neglegent (contributary), by not flying in such a way as to be able to avoid damage to the aircraft if avoidable.
Bear the "recent" fuel starvation/exhaustion accidents (where a couple of charter a/c lost power in their respective circuits), in mind. At 1.8 miles you are having an off-airport landing in a single engine, no question. Can you afford that, mr instructor? You are, after all, the PIC!
You own the wreckage if you are proved neglegent (contributary), by not flying in such a way as to be able to avoid damage to the aircraft if avoidable.
The circuit size certainly needs to be more standardised and this is demonstrated from the ASTB report from the accident at Moorabbin last July:
http://www.atsb.gov.au/aviation/occu...ail.cfm?ID=425
"Primary radar data was obtained from the radar site at Gellibrand Hill that was approximately 41 km north-west of Moorabbin airport. The Gellibrand Hill radar provided information on the aircraft that were operating in the Moorabbin MBZ down to an altitude of approximately 300 ft above ground level. Analysis of that radar data indicated that EUH conducted a wider circuit that took approximately 7 minutes to complete, whereas CNW conducted a circuit that took approximately 4.5 minutes to complete. Both circuits were within the range of circuit pattern sizes that were being conducted by other aircraft at the time. Some aircraft tracks were displaced almost twice as far from the runway on the downwind leg of their circuit as other aircraft"
http://www.atsb.gov.au/aviation/occu...ail.cfm?ID=425
"Primary radar data was obtained from the radar site at Gellibrand Hill that was approximately 41 km north-west of Moorabbin airport. The Gellibrand Hill radar provided information on the aircraft that were operating in the Moorabbin MBZ down to an altitude of approximately 300 ft above ground level. Analysis of that radar data indicated that EUH conducted a wider circuit that took approximately 7 minutes to complete, whereas CNW conducted a circuit that took approximately 4.5 minutes to complete. Both circuits were within the range of circuit pattern sizes that were being conducted by other aircraft at the time. Some aircraft tracks were displaced almost twice as far from the runway on the downwind leg of their circuit as other aircraft"
Join Date: Jun 2002
Location: Perth, WA
Posts: 215
Likes: 0
Received 0 Likes
on
0 Posts
I would go with the contention that the circuit should be of a size where you can do a glide approach and land on the runway.
This was demonstrated to me on Friday quite dramatically. I was out on a nav flight with my instructor and was down at YMUL doing some circuits. I lapsed a bit and went out on a rather wide circuit. My instructor pulled power and there was no way in heaven I could have reached the runway. On the next circuit I was tight enough to get in on a glide approach without any problems.
This was demonstrated to me on Friday quite dramatically. I was out on a nav flight with my instructor and was down at YMUL doing some circuits. I lapsed a bit and went out on a rather wide circuit. My instructor pulled power and there was no way in heaven I could have reached the runway. On the next circuit I was tight enough to get in on a glide approach without any problems.
I guess we lean towards what we learnt first; in my case, circuits with a continous turn from upwind to downwind leg using about 20 - 25 deg AOB, and same from downwind onto final, i.e. a 'racetrack' pattern circuit.
Some benefits of these are that most training-type aircraft will end up at roughly the same downwind spacing, and huge, time-consuming circuits are avoided.
Students arguably have to do more things at once with a racetrack circuit, but they aren't that hard, and they keep a bit of a lid on people drilling for miles on crosswind.
Extending downwind should be discouraged too; my 2 bob's worth.
Some benefits of these are that most training-type aircraft will end up at roughly the same downwind spacing, and huge, time-consuming circuits are avoided.
Students arguably have to do more things at once with a racetrack circuit, but they aren't that hard, and they keep a bit of a lid on people drilling for miles on crosswind.
Extending downwind should be discouraged too; my 2 bob's worth.
circuits with a continous turn from upwind to downwind leg using about 20 - 25 deg AOB
join left base for 12 which he did but about 3 miles past the TH!! This made me go even further past
One thing is certain - it is difficult for ab initio students to fit in efficiently with other traffic in a busy circuit while they are concentrating on just getting it back on the ground safely. "Arm out the Window" is right in that its the first leg of the circuit which sets the scene - spacing can be set before the turn to downwind then fly to maintain that spacing - reduce speed if necessary to avoid extending downwind.
I think one of the problems here that is yet to be identified, is the point where students are taught to turn downwind. I know of particular companies that teach not to turn downwind until reaching 1000' So a C150 and a C172/PA28 are all going to turn downwind at different points. This of course is then made a whole lot worse on the 30+ degree days and when the a/c is light say on a solo exercise.
If people were taught to turn at the same point then it wouldn't matter what you were flying.
GA driver
If people were taught to turn at the same point then it wouldn't matter what you were flying.
GA driver
Guest
Posts: n/a
GA Driver - point well made. If the aircraft is a poor performer due ambient temperatures, full fuel, overweight pilots and so on, then there is no reason why the aircraft (C150,172 etc) should not start its turn onto the downwind leg at 800 feet. In addition, the difference between the rate of climb using 15 degrees angle of bank and a medium turn at 30 degrees angle of bank is neglible for the short distance that the aircraft is actually turning - therefore it may be more advantagious to use the higher bank angle. This would keep the circuit neat and concise.
On base - an angle of bank of 30 degrees is perfectly safe and from there on it is just a case of squaring off the base leg rather than attempting an oval circuit in that position. Of passing interest is the fact that when the RAAF operated Tiger Moths at Point Cook half a century ago, there were several of these aircraft in the circuit area at any one time with no radios and accent was on keeping your eyes swivelling. All approaches were glide approaches where a normal circuit width was flown (nice and concise and within gliding distance of the aerodrome) and the throttle closed on base leg when sure of reaching the runway.
On base - an angle of bank of 30 degrees is perfectly safe and from there on it is just a case of squaring off the base leg rather than attempting an oval circuit in that position. Of passing interest is the fact that when the RAAF operated Tiger Moths at Point Cook half a century ago, there were several of these aircraft in the circuit area at any one time with no radios and accent was on keeping your eyes swivelling. All approaches were glide approaches where a normal circuit width was flown (nice and concise and within gliding distance of the aerodrome) and the throttle closed on base leg when sure of reaching the runway.
I can think of a number of reasons for wide circuits. Some justified, some not. Remember the circuit area is often defined as 3nm.
* A brand new circuit student needs more time to do things & a large circuit can help. Self limiting since as the students skill develops then smaller ciruits can progressively be flown. Similarly when converting someone onto a much faster or more complex type. There's a learning period while the poor sod's brain changes gear...
* Extending the circuit because of a slower a/c. Speed adjustment is preferable but may not be an option. So, given the choice, which leg to extend? I suggest upwind.
* Students taught to turn D/wind at 1000'. This I think is wrong. Different a/c will reach 1000' at different points. Even the same a/c will experience a changing positions due WAT effects so using altitude can't provide consistancy to spacing.
* Students taught to turn d/wind at 45deg (from the threshold or over their shoulder. Again, this won't be consistant. Presuming the 1st turn is at 500' (in Oz anyway. Not necessarily a requirement elsewhere in the world) then a/c performance will change when the x/wind turn is commenced ie how far upwind before turning. A 45deg initiated turn will then result in a variable spacing since one arm of the equilateral triangle will be variable, causing the second arm to vary. If 45deg relative to the a/c is used then the position changes according to whatever the drift allowance is.
* Students taught to turn base when the approach threshold is 45deg 'over their shoulder'. This isn't consistant - even with a constant d/wind spacing - since it changes with drift allowance.
I reckon the best(?) option is to turn x/wind when the rules & judgement allows, fly to what is visually the correct spacing then turn d/wind irrespective of height or angle, then turn base at ~45 from the rwy threshold.
My two penneth.
* A brand new circuit student needs more time to do things & a large circuit can help. Self limiting since as the students skill develops then smaller ciruits can progressively be flown. Similarly when converting someone onto a much faster or more complex type. There's a learning period while the poor sod's brain changes gear...
* Extending the circuit because of a slower a/c. Speed adjustment is preferable but may not be an option. So, given the choice, which leg to extend? I suggest upwind.
* Students taught to turn D/wind at 1000'. This I think is wrong. Different a/c will reach 1000' at different points. Even the same a/c will experience a changing positions due WAT effects so using altitude can't provide consistancy to spacing.
* Students taught to turn d/wind at 45deg (from the threshold or over their shoulder. Again, this won't be consistant. Presuming the 1st turn is at 500' (in Oz anyway. Not necessarily a requirement elsewhere in the world) then a/c performance will change when the x/wind turn is commenced ie how far upwind before turning. A 45deg initiated turn will then result in a variable spacing since one arm of the equilateral triangle will be variable, causing the second arm to vary. If 45deg relative to the a/c is used then the position changes according to whatever the drift allowance is.
* Students taught to turn base when the approach threshold is 45deg 'over their shoulder'. This isn't consistant - even with a constant d/wind spacing - since it changes with drift allowance.
I reckon the best(?) option is to turn x/wind when the rules & judgement allows, fly to what is visually the correct spacing then turn d/wind irrespective of height or angle, then turn base at ~45 from the rwy threshold.
My two penneth.
Last edited by Tinstaafl; 30th Apr 2003 at 20:02.
They will never learn. 
Join Date: Dec 1999
Location: I prefer to remain north of a direct line BNE-ADL
Age: 49
Posts: 1,286
Likes: 0
Received 33 Likes
on
10 Posts
Yeah now if I go to Morrabin I make sure I have my WAC chart and protracter when doing circuits. 1 in 60's come in handy sometimes on downwind. Thats of course if I dont have the IFR rated GPS to work out my position turning so called base. So now I just log cross country VFR NAv time when following some aircraft in the circuit. Next time when in the circuit, and I dont have that chart or GPS, Im going to declare a PAN PAN for uncertain of position. Hopefully Ill still be in radar coverage when it happens!
Join Date: Nov 2000
Location: Hong Kong
Posts: 96
Likes: 0
Received 0 Likes
on
0 Posts
As I right this reply I note that the ATSB Interim Factual report has just been posted on the ATSB Website.
It is interesting to read both that and the article in the latest issue of Australian Flying magazine.
One could believe that the one sided article in AF, the bulk of which appears to have come from the CFI at the subject flying school, is a spin job prior to the no doubt pending Coroners Inquest.
A few points to note.
1) The accident should not have happened as there were 6 aircraft in circuit. The solo aircraft was apparently the last to take off.
The ERSA states that only 5 aircraft should be in the circuit for MBZ operations at night.
The ATSB report has not mentioned this although it does refer to the AIP and what calls are required for MBZ operations.
In this respect the ATSB report is lacking.
2) The AF article points out/spins the line that the solo pilot had not been trained by the said flying school. Fine, so she was not used to the wide circuits that the school uses as its standard. Therefore one has to take the view that she had not been properly checked out and standardised by the school.
3) Do we take the view that her circuit was normal by the standard used by other schools and that the second aircraft was running a wide circuit at some 7 minutes.
4) The ATSB report puts a lot of words into discussion on the tower being closed and that aircraft were left to their own devices for circuit separation. There is an inference that all circuit traffic must be tower controlled to be safe.
If this were to be the case then any airport that has 5-6 aircraft in circuit should have a tower. How do CTAFs and Fly-ins operate without having multiple mid-airs ?
5) The ATSB report talks of the operator bringing in a requirement that the schools aircraft advise their position in the circuit by a number sequence, eg, 'number one' 'number two' etc.
This would be fine if only the aircraft of that school were in the air at that time. This is not the case.
The subject school has not advised any other school of its number sequence requirements and in any case the subject school does not write the air regulations.
6) There are continued wide circuits, excessivly wide circuits, day and night, by aircraft of the subject school.
Aircraft of the subject school continue to be involved in air and ground events that smack of lack of airmanship and lack of consideration for other users of the sky.
It is interesting to read both that and the article in the latest issue of Australian Flying magazine.
One could believe that the one sided article in AF, the bulk of which appears to have come from the CFI at the subject flying school, is a spin job prior to the no doubt pending Coroners Inquest.
A few points to note.
1) The accident should not have happened as there were 6 aircraft in circuit. The solo aircraft was apparently the last to take off.
The ERSA states that only 5 aircraft should be in the circuit for MBZ operations at night.
The ATSB report has not mentioned this although it does refer to the AIP and what calls are required for MBZ operations.
In this respect the ATSB report is lacking.
2) The AF article points out/spins the line that the solo pilot had not been trained by the said flying school. Fine, so she was not used to the wide circuits that the school uses as its standard. Therefore one has to take the view that she had not been properly checked out and standardised by the school.
3) Do we take the view that her circuit was normal by the standard used by other schools and that the second aircraft was running a wide circuit at some 7 minutes.
4) The ATSB report puts a lot of words into discussion on the tower being closed and that aircraft were left to their own devices for circuit separation. There is an inference that all circuit traffic must be tower controlled to be safe.
If this were to be the case then any airport that has 5-6 aircraft in circuit should have a tower. How do CTAFs and Fly-ins operate without having multiple mid-airs ?
5) The ATSB report talks of the operator bringing in a requirement that the schools aircraft advise their position in the circuit by a number sequence, eg, 'number one' 'number two' etc.
This would be fine if only the aircraft of that school were in the air at that time. This is not the case.
The subject school has not advised any other school of its number sequence requirements and in any case the subject school does not write the air regulations.
6) There are continued wide circuits, excessivly wide circuits, day and night, by aircraft of the subject school.
Aircraft of the subject school continue to be involved in air and ground events that smack of lack of airmanship and lack of consideration for other users of the sky.
Join Date: Feb 2003
Location: Melbourne
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
Hi All
Have spent some time reading over the posts in this forum. It seems asthough a lot of people have forgotten just how daunting it is for a wet behind the ears first timer to conduct a circuit.
The workload of a circuit lesson is far greater than any other Ab sequence in the GFPT syllabus. Whilst i find it frustrating to fly circuits on a WAC chart sometimes i try to think about how it was for me when i first started training those years ago. It is quite unreasonable to expect a tightly flown circuit from a student that has all of five hours in an aircraft.
I tend to agree with some of the points in the previous posts, some not all. However, remember these two aerodromes discussed in the forum are TRAINING aerodromes, where people come to learn to fly a circuit, they were'nt born with the judgement required to fly a pattern as close as we would all like, that is why we are instructors, we are there to teach them how to better their flying and once they gain competency in how to handle an aircraft it is then we should push for the fine tuning of the circuit.
Just in conclusion the comment in the first post regarding 737's and the recommended circuit distance is a little silly considering the performance distances between a 737 and a C150.
Have spent some time reading over the posts in this forum. It seems asthough a lot of people have forgotten just how daunting it is for a wet behind the ears first timer to conduct a circuit.
The workload of a circuit lesson is far greater than any other Ab sequence in the GFPT syllabus. Whilst i find it frustrating to fly circuits on a WAC chart sometimes i try to think about how it was for me when i first started training those years ago. It is quite unreasonable to expect a tightly flown circuit from a student that has all of five hours in an aircraft.
I tend to agree with some of the points in the previous posts, some not all. However, remember these two aerodromes discussed in the forum are TRAINING aerodromes, where people come to learn to fly a circuit, they were'nt born with the judgement required to fly a pattern as close as we would all like, that is why we are instructors, we are there to teach them how to better their flying and once they gain competency in how to handle an aircraft it is then we should push for the fine tuning of the circuit.
Just in conclusion the comment in the first post regarding 737's and the recommended circuit distance is a little silly considering the performance distances between a 737 and a C150.
I am quite surprised at this procedure from the current issue of "Australian Flying"
I have always been taught to base turning points for the circuit on my position in relation to the runway. Not some arbitrary time when an altitude is reached that varies with OAT and aircraft.
The article gives a nice diagram with a bunch of dimensions for the circuit as described above but surely these will change between the two hefty blokes in the 152 vs. the 1 light fellow in the new 172.
And to pick up on the 1.8nm distance between the downwind leg and the runway that is given in the article… I refer you to the visual circuit procedure for a 737
http://www.smartcockpit.com/b737/B73...al_profile.PDF
We then look at about 0.8nm to climb from 700' to level off at 1000' on the crosswind leg. We teach the student not to conduct a climbing turn onto the downwind leg but before the downwind turn to configure the aircraft into the cruise with correct attitude, speed, power and trim and then to conduct a medium level turn onto downwind at about a 110kt cruise, which gives you about an 0.3nm radius of turn.
The article gives a nice diagram with a bunch of dimensions for the circuit as described above but surely these will change between the two hefty blokes in the 152 vs. the 1 light fellow in the new 172.
And to pick up on the 1.8nm distance between the downwind leg and the runway that is given in the article… I refer you to the visual circuit procedure for a 737
http://www.smartcockpit.com/b737/B73...al_profile.PDF
Last edited by Wing Root; 29th Oct 2006 at 05:58.