Circuit Issues at uncontrolled aerodromes

[skippydiesel]

1 hour ago, johnm said:

this is serious stuff where lives are at risk but I can't help thinking of vehicle roundabouts and the human interpretation of what is correct

 

roundabouts: Situational awarness is required - what lane - where not to cross - when to go and where  / / how to exit; (what direction - for some); etc

 

aircraft circuits:  Situational awarness is required but there are vertical and horizontal dimensions, and speeds, heights, conflicting directions, etc

 

Both require correct human interpretation - radios will help a great deal (joining pilots can understand the likely circuit being used and who is out there using a radio properly) - but I think the human interpretation of what is the correct way to join is the big one 

 

 

Your analogy is fair up to the point of pilot training and retraining (BFR's).

 

Understanding and adhering to the rules would even make car drivers safer (& more efficient) but there will always be the human factor & the unexpected - news to day stolen car involved in 3 car "pile up",  3 dead, Old. - likely the stolen car was being driven by an unlicensed person, possibly in an erratic manor.

[facthunter]

Isn't that where the "Munsters" live?  Nev

[IBob]

Brendan, I would say make sure you have a radio that works well in your aircraft, and learn to use it to give and receive clear communication. (We all like to think we do that, but some mumble and do not enunciate clearly, and some speak in a rapid monotone, presumably thinking that makes them sound cool and professional.) Test it by asking for radio checks: some owners fit handhelds, and while they may work okay in some airframes, it's clear that they don't work well in others.
If necessary, get whatever you can to improve your own hearing inflight: I have Lightspeed Zulus, which are a major improvement over passive headsets for me.
Learn to set and use the squelch on the radio: it's not a set and forget thing, if set too high may cause you to miss calls.
And get ADS-B. It won't necessarily be used much to locate you in circuit, but what it WILL do is alert others to the fact that you are there.
 

[old man emu]

Facthunter, I wish you would use the Quote facility in some of your poasts. Not doing so makes it hard to see what you are referring to.

 

2 hours ago, facthunter said:

Isn't that where the "Munsters" live?  Nev

1313 Mockingbird Lame, Mockingbird Heights. 

[facthunter]

Helps to keep the brain active. When there's multiple subjects being discussed at the same time it's NOT easy I acknowledge. Quotes are limited and often need context. One of my pet hates is when the quote loses  the "INTENDED" meaning when out of context.  Be better if the posts were numbered as they once where. Nev

[Garfly]

11 minutes ago, facthunter said:

... Quotes are limited and often need context. One of my pet hates is when the quote loses  the "INTENDED" meaning when out of context.  Be better if the posts were numbered as they once where. Nev

 

But the full context is readily available, Nev ... usually just a couple of posts north.   Sure, any quoter should avoid twisting the OP's intention, but, at the same time, it would lead to total incoherence if you included all original 'context' when what you're referencing is but one small part of it.

 

I agree with you though, on the numbering of posts.  But I've often wished you'd make friends with the 'Quote' button.

 

By the way, what did you mean by that Munster's question?  

 

Anyway, Google being Google, and OME being OME, we did end up with the correct answer.    LOL

 

https://www.youtube.com/watch?v=HS3WPRFZ6Es

 

 

[facthunter]

"Erratic Manor" would be a good name for where the Munster's live. A joke that takes a while to GET is the best..   Nev

[Garfly]

 

" "Erratic Manor" would be a good name for where the Munster's live."

 

Ha, ha  ... thanks.  That is funny.   

 

"A joke that takes a while to GET is the best..   Nev"

 

... and  by that measure VERY funny.   ;- )

 

 

(BTW, outside parts of the lawn bowls and sports flying communities, it'll take a LOT longer still for that joke to land.  )

 

 

Edited July 21, 2023 by Garfly

[turboplanner]

2 hours ago, facthunter said:

Helps to keep the brain active. When there's multiple subjects being discussed at the same time it's NOT easy I acknowledge. Quotes are limited and often need context. One of my pet hates is when the quote loses  the "INTENDED" meaning when out of context.  Be better if the posts were numbered as they once where. Nev

This is how simple it is to use the quote function so everyone knows who it is addressed to.

[BrendAn]

7 hours ago, RFguy said:

ARO said : " The idea is to work out where other aircraft are before you try to be in the same place. "
love it. yes. so true. 

 

As for the Xair, I think you are over worried about any issue.  The Xair wont be any different from any other problem unless you are threading yourself into a circuits full of planes.  and then everybody is on their toes anyway.  If your circuits are tight 500 footers, and your timing is right, radio calling is good,  that should work just fine.   I would have thought in an Xair you wouldnt be spending hours in the circuit either.   The problem with congestion might occur if you fly too deep on downwind, or too wide etc.  But that also goes for aircraft flying 1000' circuits. The other thing, is, if uncomfortable ,  there a strip you can TO and fly to for bulk circuit work? like a croppers dirt  strip somewhere ? The Xair wont need much strip...

good points. once i have my certificate i will flying over farmland away from most air traffic. west sale and bairnsdale are pretty quiet most of the time . when i was doing lessons at latrobe valley it was very busy on some days.

[BrendAn]

5 hours ago, IBob said:

Brendan, I would say make sure you have a radio that works well in your aircraft, and learn to use it to give and receive clear communication. (We all like to think we do that, but some mumble and do not enunciate clearly, and some speak in a rapid monotone, presumably thinking that makes them sound cool and professional.) Test it by asking for radio checks: some owners fit handhelds, and while they may work okay in some airframes, it's clear that they don't work well in others.
If necessary, get whatever you can to improve your own hearing inflight: I have Lightspeed Zulus, which are a major improvement over passive headsets for me.
Learn to set and use the squelch on the radio: it's not a set and forget thing, if set too high may cause you to miss calls.
And get ADS-B. It won't necessarily be used much to locate you in circuit, but what it WILL do is alert others to the fact that you are there.
 

thanks ibob. the xair has a good icom radio and new headsets. definately need to get a sky echo i think.

[turboplanner]

20 hours ago, BrendAn said:

 flying 500ft circuits at 55knts. 

I have 55 kts cruise and 70 km/hr (38 kts) best climb speed with the 503 engine - that OK?

[kgwilson]

2 hours ago, turboplanner said:

This is how simple it is to use the quote function so everyone knows who it is addressed to.

You can also quote multiple posts by clicking the + sign. If you only want to quote part of a post you just delete the bits you don't want in the normal way (back button, select & delete button or delete & hold for forward delete).  Easiest on a PC.

[Garfly]

 

20 hours ago, BrendAn said:

just when i thought it was safe to fly i read all the near misses in this thread. its pretty sobering. what worries me is i have bought an xair because i decided i want to fly low and slow and land in paddocks so i got rid of the jabiru. now after reading this thread i wonder if i will be a sitting duck flying 500ft circuits at 55knts. i have radio but should i be getting a skyecho .  i am thinking of faster aircraft dropping in on me on final .

 

15 minutes ago, turboplanner said:

I have 55 kts cruise and 70 km/hr (38 kts) best climb speed with the 503 engine - that OK?

I didn't get the impression that BrendAn was unfamiliar with the specs of the aircraft he's already bought.  Maybe I missed something.

[BrendAn]

5 minutes ago, Garfly said:

 

 

I didn't get the impression that BrendAn was unfamiliar with the specs of the aircraft he's already bought.  Maybe I missed something.

582

[turboplanner]

16 minutes ago, Garfly said:

 

 

I didn't get the impression that BrendAn was unfamiliar with the specs of the aircraft he's already bought.  Maybe I missed something.

You did.

[turboplanner]

12 minutes ago, BrendAn said:

582

OK TKS - do you have a Best Climb Speed (kts or km/hr) for that?

Edited July 21, 2023 by turboplanner

[Garfly]

1 minute ago, turboplanner said:

You did.

Sorry.

[Ironpot]

CASA are holding a webinar today: maybe of interest?

Might be too late to register?

 

 

https://www.eventbrite.com.au/e/webinar-non-controlled-operations-the-rfds-experience-tickets-677098518897?keep_tld=1

[facthunter]

Don't know, but they would be a good idea.  Nev

[BrendAn]

On 21/07/2023 at 5:40 PM, turboplanner said:

OK TKS - do you have a Best Climb Speed (kts or km/hr) for that?

sorry, i missed this question.  best rate of climb  around 40 knots .

the figures you posted look pretty right. the book says 55 eco cruise and 65 fast cruise.

Edited July 28, 2023 by BrendAn

[turboplanner]

6 hours ago, BrendAn said:

sorry, i missed this question.  best rate of climb  around 40 knots .

the figures you posted look pretty right. the book says 55 eco cruise and 65 fast cruise.

I'm just working on a couple of others and then I'll post it in the pattern with various other aircraft based on their perfromance, then we can look at what we could see from the left seat of each aircraft at each step of the circuit.

 

I found the best climb speed (Vy) for the X-Air/582 at 45 kts compared to a Cherokee Warrior of 79 kts, but it punches well above its class with a Rate of climb of 1000 feet/minute vs the Warrior's 649 ft/minute.

[turboplanner]

I've limited the comments here to See and be Seen, not implying anything about electrinic separation or radio - this was already longer than I expected.

 

 

BACKGROUND:        Visual Flight Rules Guide (CASA VFRG VER.7.2

https://www.casa.gov.au/sites/default/files/2022-02/visual-flight-rules-guide.pdf

 

Reading the VFRG or [in brackets] short cut to jump to a page

P241 = page number of the CASA PDF printed document

[253] = page number of the Interactive version from the above link.

 

To get around quickly:

(Click the link above > where you see 1/556 at the top (1 of 556 pages), overtype the “1” with “253” then overtype the 253 with the next page you want.

 

Circuit Procedures

P241 [253]      Circuit Procedures at non-controlled aerodromes.

 

P242 [254]       “You must land and take-off into wind.” This becomes the Duty Runway.

 

P243 [255]       Standard traffic pattern = turns to left.

 

P244 [256]       Maintain take-off track until 500’

                        (Each aircraft will be turning based on its climb rate and speed to 500’)

 

P245 [257]       Note that at non-controlled aerodromes there are three circuit levels for:

 

·       Low Performance  (70 kt, Drifters, Thrusters, Trikes etc)

·       Medium Performance (Aircraft around 90 – 120 kt cruise)

·       High Performance (High speed, RPT, Charter etc)

 

REFER to Circuit diagramme WX00232.jpg modified from the VFRG.

 

P247 [259]       Arrivals, Departures, Transits.

 

Circuit Procedure

Apart from the three different performance groups, aircraft with different performance will be flying a rectangular circuit on different tracks because some reach 500’, 1000’ points faster than others.

 

·       Slower aircraft will always be a nuisance because they will be out wide and can come in without warning. You have to give way to those slower aircraft on your right if there’s a chance of collision.

 

·       Faster aircraft will always be a nuisance because they will be pushing up from behind where you can’t see them.

Reading the circuit on approach is a skill. 

You’ve come in from a cross-country flight, sometimes stressed, sometimes tired and you can’t stop at a stop sign and take a breath; you have to keep going and jump on a merry go round travelling at a relatively high speed.

And you can’t all see each other all the time.

 

Probably the best vista to size it all up is an entry mid downwind because you are close to the centre of all the circulating aircraft – it’s about the same distance to crosswind and base, and you have the long length or the rectangle to decide just where you are going to jump onto downwind. If you enter at 1000’ +- 20’ the ones coming up from behind at 1000’ only have to turn their heads slightly left or right, and you’re not hidden against the ground colours.

 

Probably the worst entry is a straight in approach.

This is usually where you will find the person who is way behind on recency and isn’t really sure what to do in the circuit and will come in regardless of anyone circulating because he’s at maximum stress and in a panic. He might give a radio call but he might not.

 

Let’s say you are not that person, and it’s you coming in; it gives you the longest distances to see active aircraft and the poorest view to assess their positions. The benefit of the rectangle is that it gives you common judgement steps.

 

VFRG (Visual Flight Rules Guide) Disclaimer

I’m just focusing on a few interesting items here, not giving you anywhere near the full version; for full regulations go to the VFRG and CASA website.

 

Rules for Prevention of Collision (VFRG P054 [66])

 

Basic Rule P054 [66]

During a flight, a flight crew member must maintain vigilance, so far as weather conditions permit, to see and avoid other aircraft (AC91-14 information on and the limitations of see and avoid).

 

Radio Communication Procedures P349 [361]

 

            Initial Call P357 [369]

            Non Controlled airspace/aerodromes P358 [370)

            Radio Broadcasts in CTAF P363 [375] Note “MUSTS”, “RECOMMENDED”

 

 

Circuit Procedures at non controlled aerodromes. P241 [253]

 

            Low Performance Aircraft on 500’ circuit

“You must not commence take off until a preceding departing aircraft using the same runway:

·       Has crossed the upwind end of the runway

·       Has commenced a turn   (plus further dot points)

 

Maintain same track after take-off until 500’ AGL (P244 [256]

 

 

Right of Way

CASR Part 91 General Operating & Flight Rules Ver 3.1, June 2023

https://www.casa.gov.au/sites/default/files/2021-08/plain-english-guide-part-91-new-flight-operations-regulations-interactive-version.pdf

 

P48 [50]           Right of way rules 91.330

P49 [51]           Additional Right of way rules 91.335

P50 [52]           Right of way for take-off and landing 91.34

 

P116 [118]       Straight in approaches at non-controlled aerodromes (91.395)

                        “Before commencing a straight-in approach you must determine the wind direction and runways in use at the aerodrome.

                       

(and more – available in the CASR document link above)

 

 

Modelled Circuit Tracks – File WX00243

Following some near misses recently where people commented that they wanted to avoid a repeat, I did some research and modelling (which is not related to those cases).

 

Disclaimer:

None of the modelling below or notes in this post are for flying use. I haven’t included the helix turns in the circuit, which will push the tracks outwards, the scale is based on Google Earth measurements to landmarks based on aircraft performance, and the aircraft performance proved very difficult to get because not many manufacturers/pilots seem to be doing the exercise I did. There are airfields that don’t follow this practice, and there are plenty of pilots who will just fly out of their track and form a single line behind the aircraft in front. I didn’t factor winds in.  So these notes and drawings should only be used as thoughts.

 

 

Practical

Instead of teaching students how to judge the turning points in a circuit to comply with the correct turning points, some instructors show them landmarks, e.g. “You turn onto Crosswind at the highway, Downwind at the big dam, Base at the two-story house and Final at the football ground.

 

Possibly they think it makes it easier for a new student and easier for them to look up and see what their students are doing, but that’s not in the VFRG and people flying in, often with much faster aircraft and often tired from a long trip will not be flying that rectangle, so you have a chance of a collision.

 

Worse, If they don’t step you up to correct circuit procedure then when you go to another airport, (a) you’ll find no highway, no dam, no two-story house and no football ground; inventing something else on the spot is introducing a collision risk.

 

The VFRG diagramme shows one of each distinctly different performance aircraft, Low Power (Drifter, Thruster, X-Air etc) on the 500’ circuit level, Medium Power (Jabiru, Piper Cessna Beechcraft etc.) on the 1000’ circuit level, and High Power (Qlink etc) on the 1500’ level. Many recreational pilots flying may not have regularly encountered these levels because there is no regular Commercial service into their airport, but there’s nothing to stop a Charter coming in one day when you’re all relaxed on circuit. And in some cases low power operators on this site have boasted that they fly the 1000’ circuit because they can….until a Beech Baron turns the corner behind them and cuts their tail feathers off.

 

And there is nothing to get the blood pressure up more than a radio call from a Heavy Passenger Helicopter that he’s on straight in on runway “shsh” and you have to figure it out.

 

One day you may fly to an airport which regularly has all three power ranges mixing, so I’d recommend spending some time on the VFRG to see what your obligations are.

 

If we look closely at the VFRG diagramme (WX00232) we see shadows on the ground showing their tracks.

We can see that on crosswind, where they turn crosswind at 500’ and where the medium and high performance turn downwind they each have their tracks, and turning Base at 45 degrees past the runway end they are still running three wide, but all resume a common track for Final.

 

Knowing this gives us a better understanding of where we will be looking in each part of the circuit for all but the mavericks.

 

And knowing this sharpens your focus on threat areas. Hunters know that looking for the sharp edge of an ear in long grass gives them a far better return than looking for the complete furry body of a rabbit, even though they may be scanning a complete paddock.

 

If our circuit tracks are based on our aircraft performance then what can we expect to see in a busy circuit of 10 to 12 aircraft?

 

To show this I’ve picked Cunnamulla Airport, away from the town and with pretty much no features at all.

 

The pilot in command has picked a Cherokee Arrow, flying out of Melbourne a good half hour after first light, planned a fuel stop at Hillston NSW, and should be in Cunnamulla, Qld for lunch, arriving around 11:30.

 

He has a wife and two small children on board.

 

The Hillston fuel stop takes an hour because he forgot to book.

 

Approaching Bourke he is transitioning from the Southern Meteorological system to the Northern system and notices storm cells in the distance ahead.

 

After passing Bourke he sees a huge storm cell looming up ahead, and at Ford’s Bridge he amends his flight plan to divert to Thargomindah and assess the storm cell from there.

 

He checks his fuel burn and realises he won’t make Cunnamulla with the diversion, so plans a refuel at Thargomindah. The aircraft starts to bounce and one of the kids throws up all over his shoulders; he feels it dribbling down his back.

 

At Thargomindah they fuel up and clean up. The sky has cleared all the way to Cunnamulla.

 

They’ve missed lunch and the pilot by now is feeling some fatigue and stress. The last thing he needs is more surprises.

 

The first thing he notices is that there is no highway, no big dam, no two-story house, no football ground, but he can handle that because he has been trained to fly the performance circuit.

 

The second thing he notices is that it’s the Annual Cunnamulla Circuit Flying Championship and there are nine aircraft in the circuit. As much as he is stressed by the delays, diversion and throw up, this isn’t a problem because he took the time for a few flights at an airfield where 10 to 12 in the circuit was a regular event.

 

He comes in towards mid-downwind, and surveys them all rotating. The Baron is the one he has to be careful of because he can’t go any faster, but he can slow down with flaps, attitude and throttle if he gets a slow one, so he fits in behind the Baron, adjusts his spacing and makes an uneventful landing.

 

The circuit he was looking at is attachment WX00243.jpg

 

Circuit Track Summary (WX00243.jpg)

Following recent posts on Airproxes with the pilots saying they don’t ever want to experience it again, I’ve spent a lot of time on this because I had an aircraft fin slide from left to right across the windscreen, followed it up and pretty much go an official Sh!t happens response.

 

Radio Separation

Postwar into the 1960s and 70s we relied on Radio calls for separation. 12 aircraft in a circuit all flying under tower supervision, all calling “XXX Base” works albeit if there’s a lot of congestion around the base turn one or two will have to turn first and call asap. However, since whoever calls first gets to Final first, it wasn’t unusual for someone to call base and cut the corner or call base before they got there and others to forget their call and others to call base on downwind etc. So in some respects its understandable that handing liability over to pilots happened, but we lost that circuit time stamp.

 

 

 

Electronic Separation

If you want to rely on electronic separation, the equipment reliability has to be up to TSO standard, and it has to see every aircraft. You carry the liability, so miss one and you’re gone legally because the industry benchmark is see and be seen.

 

See and be seen

I consider this a lot less safer than radio, but this is the benchmark we have to work to, so I tried to replicate a circuit full of aircraft with different performance in an effort to find out how many we can see in different parts of the circuit.

 

Bear in mind:

·       I’ve drawn the tracks from the best aircraft data I could get, so there’ll be some variance there.

·       Some pilots will only know fixed landmarks, and at places like Cunnamulla could be anywhere.

·       Some pilots will be flying diagonally to form a line behind the aircraft in front as early as Crosswind.

·       Some pilots will be shortening a leg to get ahead of another aircraft.

·       Some pilots will be extending a leg to build some landing space on Final.

 

We’ll just start with where they would be based on the VFRG performance basis.

 

When we calculate Best Climb Speed (Vy) and Best Climb Speed from 0’ to 500’ on the take- off leg, and 500’ to 1000’ on Crosswind we find:

 

·       The total spread for all tracks is 1.2 Km from inner to outer.

·       The main concentration of aircraft (6 out of 11) is within 300 metres spread.

·       Four Aircraft, (Jabiru, Arrow, Cessna 150, Cessna 210 are within 66 metres spread.

So although the aircraft seem to be all over the place most are within reasonable sighting distance throughout the circuit.

 

However, an aircraft which is making a straight-in approach will be letting down approximately 4km (2.2 Nm) out from the end of the strip, and 3.5 km (1.9 Nm) out from an X-Air on base, so the straight-in aircraft has a much more difficult task seeing the downwind traffic which will reach their Final turn at roughly the same time as he reaches that point, and the people in the circuit will usually not be expecting someone making a straight in.

 

In addition, if it’s a Baron, C210 or Arrow coming in there’s going to be a question of whether the pilot is ahead of the aircraft or behind it as he/she does the pre-landing management, so the stress level of the existing circuit pilots goes up, and  it’s likely that those three are going to figure in a who got to Final first and who has to go round competition.

 

The calculations which produced the circuit tracks on WX00243.jpg combine both climb in ft/min and climb speed.

 

The X-Air with 582 engine has the second best climb rate at 1000ft/min, (but it also has the slowest forward climb speed at 45 kts); it will get to 500’ in a shorter distance than the bigger and faster aircraft, but will a faster aircraft with an impatient pilot take off too soon and intercept its path?

 

Something to remember if you are following one because you have to give way to it. Bullying smaller aircraft out of the way is not included in the rules and often, where a pilot of a recreational aircraft does an unorthodox quick departure from the circuit he/she becomes a bullseye target for a legitimate pilot following the correct circuit procedure further out. Plenty of RA pilots over the years have posted that they do that on a regular basis; good Airprox fodder.

 

Next best climber is the Baron, turning a little further out, but it’s climbing at 105 kts, 2.3 times the speed of the X-Air and faster than most of the others.

 

Then the Morgan

 

Then the Jab 230-D and a batch of long-time GA training aircraft which will usually be visible as a single line of aircraft and will attract other lost mavericks to come in or out, usually as quickly as they can, so there’s a side visibility issue.

 

The Warrior, with its high lift wing takes longest to make 500 feet but is a lot faster than the X-Air in the climb which is why it takes the longest distance to turn crosswind at 500 feet.

 

Since Crosswind is just another 500 foot climb to 1000 feet all repeat the same pattern for Downwind, where they all should be exactly on 1000 feet, so at least all you have to do is look out sideways………but they’re not are they, some are 100 feet above you, some below, particularly those who’ve come in to join the line, sometimes straight in front of your nose.

 

The Base turn is where the field can break up.

If they all look over their left shoulder and sight the wingtip at 45 degrees out from the runway centreline, they’ll all replicate the same pattern of turns they did in the Downwind turn, and all replicate the same spacing apart on Base – even a places like Cunnamulla.

 

This is where the people trained to turn at a fixed point like the two-story house can really stuff up a busy circuit because they could jump the queue or fall behind without any notice, so this is a danger point.

 

I mentioned earlier that although the aircraft are all running in different tracks, the tracks are reasonably close together so from about the start of Downwind an attentive pilot will be speeding up if he is ahead of a faster aircraft or slowing down if he is behind a slower aircraft, so that by Final they have all built even distances between themselves which allows the first aircraft to vacate the runway before the second one touches down etc.

 

Since they all turn on to Final on the extended centreline of the runway some shuffling on Final may be required along with some go rounds.

 

In this case with the green line of the X-Air activating the low power circuit, we will be looking across to the left on Base to see where he is and when he might be joining Final where we will need to allow a much greater space for his slow speed.

 

All of the above is based on a Left Hand Circuit and “he” includes “she”.

 

How could you practically make use of the circuit diagramme?

 

Try the pen/pencil/toothpick etc. pointer, pick an aircraft with performance similar to yours, rest the peg on the thin blue line across the runway above the “30” and visualise what you would see in that view.

 

A white Jabiru against a grey sky can be hard to see from behind, but when it banks into a turn the wings become very obvious, so looking up the strip to the 500 foot turn points you’ll see who you’re going to be following.

 

Rest the pointer bit by bit along the circuit to try to figure out where you will get the best views.

 

Try it out a bit at a time when flying and keep the things that give you a better view than you’re getting now.

 

You’re still scouring the whole paddock, but like the hunter, you can look for the ears.

 

 

Edited August 18, 2023 by turboplanner