The hit and miss art of CTAF separation.

[Garfly]

I think we've discussed this particular (non-fatal) accident on here before. But seeing the video again, I'm reminded of just how under-prepared some of us are for the complex job of self-separation in busy circuits. It can demand high levels of comms skills - of the speaking and listening kind -  and heaps of mental spatial image processing; all this, when we're pretty busy anyway, just keeping our own craft under control through its lowest, slowest phases of flight.

If you happen to fly a lot from busy uncontrolled strips, or have done your training at one, you'll have gained competence and confidence as you go. But if you're a low time pilot, say, who's trained at a quiet strip - or, for that matter, at a towered airport - you could, though fully licensed, be quite unprepared for that challenge.  It's almost like this particular competence should be more formally taught and tested.

 

Anyway,  there's a useful discussion of the issue in the YT comments. 

 

An example:

 

 

MilkBoy17

10 months ago

Seems like people are reporting what THEY are doing without listening to what others around them are doing. People mention low wing vs high wing not being able to see each other but they both reported on final multiple times with nearly matching distances. If anyone had been listening instead of just speaking, they would have realized something was amiss.

Gnomish 8

Exactly. That last call would have made me extremely nervous (1 mile final, 0.8 mile final). 8VK pulled a "I'm first in line, I'm just gonna keep doing my thing" instead of recognizing, "Hey, they're pretty much right on top of us, the smart thing to do here is to re-enter the pattern, get visual, and space appropriately." Seriously, a .8 mile final call after someone's reporting a 1 mile final is nothing short of "I'm first in line." 540LK had all the info, too. They should have known they were incredibly close behind someone, and been checking the entire way. They knew they should have seen a plane on the ground in front of them, but instead of paying attention, they just decided to keep doing their own thing... 8VK totally was in the right legally -- they were #1 and had been reporting their position. But being legally correct isn't much solace after a midair... Being in a rush gets you killed. Taking an extra 5 minutes to re-enter the pattern and properly space would have prevented this entirely. I hope we're all able to look at this as a learning experience and make ourselves better because of it.

 

 

 

Edited August 24, 2021 by Garfly

[cscotthendry]

There is also this:
On a long trip with a group, I ended up in a situation where another aircraft was above me in close proximity. I could hear him transmit to me telling me that we were close together, but he couldn't hear me. My guess is that his antenna was on the top of his metal plane and the plane was blanking my transmissions. I'm not sure why I could hear him. Maybe it was the signal strength. That is, the attenuation from his metal airframe had more impact on his received signal than on his transmitted signal.

It was a scary situation because I knew he was close and I kept asking him what height he was at (about six times in the space of about 30 seconds) and he kept calling me to see if I'd heard him say we were close together.

[Thruster88]

I listened without watching the screen and tried to pin the position of each aircraft as they made calls. The kids game of pin the tail on the donkey is easier. Lots of non standard phrases, not enough early, mid or late positions, not saying type with each call, same aircraft using different call signs, it's a crap shoot. Give me adsb in and out please.

[walrus]

I have ADSB and my initial comment is that relying on it in a circuit is potentially suicidal for two reasons.

 

1. You do NOT want your head down looking at a screen and trying to make sense of positions - you don’t have enough time. You are just asking to lose situational awareness.  You need to be looking out because things happen fast. This is especially important if there is confusion about north up/track up, someone with a bad radio, poor english, verbal dihorea , wrong runway selection, etc.  or marginal flying skills like me.

 

2. Unless you can ensure that everyone has an operating ADSB out capability, you  cannot positively ensure your own separation. You can receive a false sense of security.

 

Where I currently value ADSB is:

 

(a) setting up my circuit entry where there are likely to be multiple players before I make my entry and first radio call. I might decide to do an orbit and wait for the RV rocket behind me to go first, or helimed or Vicpol or firebird. 

 

(b) away from the circuit, ensuring separation with the many aircraft I would never normally even see. 

 

It’s great to have it but be careful to confirm what you see on the screen.

[RossK]

I've had a couple of incidents where another plane has reported position exactly where I am 😲. It really gets the adrenalin going.

First was in the circuit when I was mid turn from crosswind to downwind, the local Jump plane called joining downwind 😬. A quick scan couldn't find him so I called him and reported my position. He replied that he was 500m off my left wing and slightly higher - got him, and he had me visual. He overtook me and turned base about 500m in front, those guys are always in a hurry.

Second was on the VFR route from Kilmore to Sugarloaf. As I was abeam Yan Yean I reported that I was 2 miles abeam Yan Yean at 2500 tracking to sugarloaf. Within 10 seconds there was a call from a GA plane saying he was 2 miles abeam Yan Yean at 2500 tracking to sugarloaf. a quick scan found him about 1 mile further out and about 500ft higher. Not sure if he was trying to be annoying or not, as he was clearly not on the VFR route and in the 4500 class C step, or he just didn't really know where he was.

 

[Garfly]

4 hours ago, walrus said:

I have ADSB and my initial comment is that relying on it in a circuit is potentially suicidal for two reasons.

 

1. You do NOT want your head down looking at a screen and trying to make sense of positions - you don’t have enough time. You are just asking to lose situational awareness.  You need to be looking out because things happen fast. This is especially important if there is confusion about north up/track up, someone with a bad radio, poor english, verbal dihorea , wrong runway selection, etc.  or marginal flying skills like me.

 

2. Unless you can ensure that everyone has an operating ADSB out capability, you  cannot positively ensure your own separation. You can receive a false sense of security.

 

Where I currently value ADSB is:

 

(a) setting up my circuit entry where there are likely to be multiple players before I make my entry and first radio call. I might decide to do an orbit and wait for the RV rocket behind me to go first, or helimed or Vicpol or firebird. 

 

(b) away from the circuit, ensuring separation with the many aircraft I would never normally even see. 

 

It’s great to have it but be careful to confirm what you see on the screen.

 

True, most would agree that ADSB IN/OUT, as currently deployed in Oz, is more of an alerting tool for terminal areas than it is for the circuit, per se.  That being said, reliance on any method of separation in the circuit can be potentially suicidal. And that includes (as the video well shows) good old fashioned 'alerted see and avoid' (radio-on/eyes-out).

Whilst I agree that heads down in the circuit is not at all to be recommended (for the reasons Walrus lists) if, in the case of the video accident, ADSB had been working in both aircraft and set up for glancing at - as opposed to fixating on - the collision surely would have been avoided (a more feasible scenario in the US where ADSB IN/OUT is close to universal). The close and closing threats would have been obvious at a glance (whereas not, it seems, from peering outside into clear blue sky).

 

In fact, the mental load Walrus cites: 'trying to make sense of positions' is precisely what the device's visual display has already taken over for you.   It's 'making-sense' via the oral/aural route that's really mind-consuming: all that half-heard (mis-heard), stepped-upon, garbled, sometimes plain-wrong, info-babble.

 

So it's not smarter to have eyes outside searching sky-left when the threat is coming from sky-right (or, worse, sky-high or sky-low) because someone said (or we thought we heard) "east" when "south-east" was what was meant.  Or, more to the point, "cross-wind" when "mid-field, cross-wind" was what was meant.

 

I've said it before; when properly set up, an ADSB-IN display, can be compared to the mirrors we rely on (but not entirely!) while driving.  Staring into your mirrors trying to work out what the traffic behind is up to is not considered best practice anywhere, by anyone. On the other hand, integrating mirror glances into our driver's scan is expected practice on the road. Mirrors give us crucial info - and quickly - that no amount of full-frontal ever can.

 

But sure, I realise that it'd be a rare case when ADSB would, in practice, come in handy in the circuit if for no other reason that we probably wouldn't have it set up for that 'glimpse' mode.  (Unless we were expecting trouble, which we usually aren't because usually the system works well enough. Until ...)

 

But anyway, just hearing of the cases other posters mentioned makes me, like Thruster, look forward to the day when ADSB IN/OUT (whether the proper ones or our cheap-skate conspicuity devices, becomes more or less universal here in OZ.)

 

Just in recent weeks flying around the fairly busy Port Macquarie - Taree area I've had multiple occasions where my SkyEcho2 has come in useful in arranging safe separation around terminal areas (usually with commercial aircraft like Air Ambulances and choppers and RPTs who are always ADSB equipped.) 

 

Like others, I have been amazed at how often I fail to pick up with my eyes the very close targets that the display tells me (and the radio confirms) are right out there.

 

 

 

 

 

 

 

 

 

Edited August 25, 2021 by Garfly

[cscotthendry]

17 hours ago, Garfly said:

 

True, most would agree that ADSB IN/OUT, as currently deployed in Oz, is more of an alerting tool for terminal areas than it is for the circuit, per se.  That being said, reliance on any method of separation in the circuit can be potentially suicidal. And that includes (as the video well shows) good old fashioned 'alerted see and avoid' (radio-on/eyes-out).

Whilst I agree that heads down in the circuit is not at all to be recommended (for the reasons Walrus lists) if, in the case of the video accident, ADSB had been working in both aircraft and set up for glancing at - as opposed to fixating on - the collision surely would have been avoided (a more feasible scenario in the US where ADSB IN/OUT is close to universal). The close and closing threats would have been obvious at a glance (whereas not, it seems, from peering outside into clear blue sky).

 

In fact, the mental load Walrus cites: 'trying to make sense of positions' is precisely what the device's visual display has already taken over for you.   It's 'making-sense' via the oral/aural route that's really mind-consuming: all that half-heard (mis-heard), stepped-upon, garbled, sometimes plain-wrong, info-babble.

 

So it's not smarter to have eyes outside searching sky-left when the threat is coming from sky-right (or, worse, sky-high or sky-low) because someone said (or we thought we heard) "east" when "south-east" was what was meant.  Or, more to the point, "cross-wind" when "mid-field, cross-wind" was what was meant.

 

I've said it before; when properly set up, an ADSB-IN display, can be compared to the mirrors we rely on (but not entirely!) while driving.  Staring into your mirrors trying to work out what the traffic behind is up to is not considered best practice anywhere, by anyone. On the other hand, integrating mirror glances into our driver's scan is expected practice on the road. Mirrors give us crucial info - and quickly - that no amount of full-frontal ever can.

 

But sure, I realise that it'd be a rare case when ADSB would, in practice, come in handy in the circuit if for no other reason that we probably wouldn't have it set up for that 'glimpse' mode.  (Unless we were expecting trouble, which we usually aren't because usually the system works well enough. Until ...)

 

But anyway, just hearing of the cases other posters mentioned makes me, like Thruster, look forward to the day when ADSB IN/OUT (whether the proper ones or our cheap-skate conspicuity devices, becomes more or less universal here in OZ.)

 

Just in recent weeks flying around the fairly busy Port Macquarie - Taree area I've had multiple occasions where my SkyEcho2 has come in useful in arranging safe separation around terminal areas (usually with commercial aircraft like Air Ambulances and choppers and RPTs who are always ADSB equipped.) 

 

Like others, I have been amazed at how often I fail to pick up with my eyes the very close targets that the display tells me (and the radio confirms) are right out there.

 

 

 

 

 

 

 

 

 

All this discussion and the fact that other airplanes are hard to spot even at relatively short distances, brings to mind the discussions past about radios in planes.

I remember some comments from people with very simple aircraft that they”didn't need a radio” because they could “see and avoid” and that this was superior to having a radio anyway.

But then, even having a radio is not the be-all end-all either.

I remember a situation at Gympie where I joined the circuit on crosswind with a radio call announcing such. I turned and tracked downwind and at the point where my finger was descending on the PTT to announce my turn to baseon 14  I heard “Gympie traffic Jabiru ???? Is turning base 14” WHISKEY TANGO FOXTROT!!! Where did HE come from? I heard no radio calls from him prior to that, neither did my pax, a very experienced pilot. I held my breath waiting for the hit and extended downwind and saw the Jabiru shoot out directly underneath me.

Since then and after a number of other circumstances with crap Jabiru radios, I have no faith in whatever radios Jabiru put in their planes at all.

[Thruster88]

The scary part is that you would have been tracking close to the other aircraft for a minute or so. Considering aircraft fly in three dimensions they have a lot of blind spots. 

[RossK]

1 hour ago, cscotthendry said:

Since then and after a number of other circumstances with crap Jabiru radios, I have no faith in whatever radios Jabiru put in their planes at all.

Fuel pump off helps with radio transmission apparently.

 

Technically, turning base is the only call you're required to make, so if he was doing circuits that's all he would be making. But yes, he should have heard your joining call and either spotted you and made room, or called you and let you know where he was, so you could make room.

 

I am aware of some pilots that think that as they are in the circuit, they have right of way, so the only call they need to make is turning base and the onus is on the joining pilots to see and avoid - similar to some guys I sail with who won't call starboard as the the onus is on the port tacker to see and avoid them.

Neither is great when the give way person doesn't see them and a collision occurs.

Both water and air are very unforgiving environments to have that attitude.

[pmccarthy]

When unsure of nearby traffic, there is a lot to be said for weaving about a bit and looking all around. The weaving makes you easier to see too. as long as you stay in the pattern.

[kiwiaviator]

I recently attended a breakfast flyin in NZ which hosted 54 aircraft. This meant a lot of different aircraft in the circuit area in a short amount of time with no major issues. I guess everyone was a lot more aware. I made the decision to do a overhead rejoin at 500' above the normal altitude. This gave me a better assessment of incoming traffic. Another tool in the box.

[facthunter]

Try to be where the others aren't.. It's a policy i've tried to  apply in principle where possible all my flying life. IF you are flying in a group or in a circuit with say 5 in it ,You MUST know where everyone is unless you are working positive separation by radio by a fool proof  method. (altitude). If people tell you they are somewhere they are not. (common) THAT makes things really difficult. Nev

[cscotthendry]

5 hours ago, RossK said:

Fuel pump off helps with radio transmission apparently.

 

Technically, turning base is the only call you're required to make, so if he was doing circuits that's all he would be making. But yes, he should have heard your joining call and either spotted you and made room, or called you and let you know where he was, so you could make room.

 

I am aware of some pilots that think that as they are in the circuit, they have right of way, so the only call they need to make is turning base and the onus is on the joining pilots to see and avoid - similar to some guys I sail with who won't call starboard as the the onus is on the port tacker to see and avoid them.

Neither is great when the give way person doesn't see them and a collision occurs.

Both water and air are very unforgiving environments to have that attitude.

Yes, I've encountered people like that, on the water and in the air and on the road. And they might be dead right one day. Like the guy who jumps out infront of an oncoming truck and is certain he has the right of way, but still gets squashed by the truck.

[facthunter]

Development of situational awareness is the key.  Cover the situation you are in allowing for the possibility some others aren't good at it.. Don't just trust to luck. Nev

[Thruster88]

These two aircraft would have been in each other's blind spot before and after the collision. No serious injury but six people could have died, $900 for a SkyEcho is cheap insurance, not the total answer but there is no downside. 

 

Edited August 26, 2021 by Thruster88

[pmccarthy]

The outcome of that mating would be a Cessna 190 or 195.

[Thruster88]

22 minutes ago, pmccarthy said:

The outcome of that mating would be a Cessna 190 or 195.

Since it is a straight tail 182 that could be converted to a 180 that is possible. But more than likely the pups would have a nosewheel😥.  

[Garfly]

And close calls such as this one, 5 years ago, would be obviated by universal (even basic) ADSB gear.

 

 

https://www.atsb.gov.au/media/5770910/ao-2016-017-final.pdf

 

 

ATSB comment

 

This serious incident highlights the issues with different performance aircraft operating in the vicinity of non-controlled airports. Although the crew in all three aircraft were making all the required broadcasts, in this occurrence, the broadcasts were being made within seconds of each other on different frequencies. This meant that the crew of both RZP and MYI had missed the opportunity to gain a full appreciation of the other’s position, resulting in a near collision.

 

In the last five years, the ATSB has received almost 100 reports of near collisions, where the pilots have reported that they were in the vicinity of a non-controlled airport. The ATSB is currently working on an update of the research report into safety in the vicinity of non-controlled aerodromes (previously published in 2010). A revised iteration is expected to be released in the 2016/17 financial year. The ATSB is also compiling a special aviation short investigation bulletin involving several recent near collisions in the vicinity of non-controlled aerodromes. Much of the information the ATSB has gathered through the reporting process and through related investigations points to a lack of understanding between pilots of different operation types operating to and from non-controlled aerodromes.

 

Although broadcasting and reporting on the radio often occurs, the situational appreciation of the other aircraft’s performance and positions has not occurred. Situational awareness around high traffic routes in Class G airspace and non-controlled airports remains the responsibility of the pilot in command. The ATSB encourages pilots to consider other operations in a shared facility such as non-controlled aerodromes. The use of all available resources to confirm the intent of other aircraft by questioning transmissions which had not been fully heard or understood, as in this case, may avert a serious incident such as this.

 

[ADS-B, or automatic dependent surveillance – broadcast, automatically broadcasts the precise location of the aircraft via a digital data link. The data can be used by other aircraft and ATC to show the aircraft’s position and altitude on display screens without the need for radar.]

 

 

 

[aro]

1 hour ago, Thruster88 said:

These two aircraft would have been in each other's blind spot before and after the collision. No serious injury but six people could have died, $900 for a SkyEcho is cheap insurance, not the total answer but there is no downside.

What is the delay between the ADSB transmission and the aircraft appearing on the screen? If it's 15 seconds, the aircraft will have moved 1/4-1/2 mile or more from the displayed position. That makes it little use in the circuit. You are better off spending the time identifying the traffic out the window.

 

There is a reason ATC have large minimum separation standards when they are separating aircraft using radar returns on a screen.

[kiwiaviator]

16 minutes ago, aro said:

What is the delay between the ADSB transmission and the aircraft appearing on the screen? If it's 15 seconds, the aircraft will have moved 1/4-1/2 mile or more from the displayed position. That makes it little use in the circuit. You are better off spending the time identifying the traffic out the window.

 

There is a reason ATC have large minimum separation standards when they are separating aircraft using radar returns on a screen.

Not sure what the latency is with a typical ADSB packet however I believe there is some compensation occurring in the system. I use my Skyecho info to assess the big picture eg. sequencing into a non controlled aerodrome with RPT and other traffic which is common here in Newman. I don't use it in lieu of looking out the window.

[Thruster88]

50 minutes ago, aro said:

What is the delay between the ADSB transmission and the aircraft appearing on the screen? If it's 15 seconds, the aircraft will have moved 1/4-1/2 mile or more from the displayed position. That makes it little use in the circuit. You are better off spending the time identifying the traffic out the window.

 

There is a reason ATC have large minimum separation standards when they are separating aircraft using radar returns on a screen.

I could be wrong, however for the SkyEcho2 there would be no latency.  It is receiving and sending the signal directly to from other airborne ADS-b transponders or SkyEcho's or similar devices, there is no third party involved. Perhaps RFguy could say for sure.

Edited August 26, 2021 by Thruster88

[Garfly]

 

52 minutes ago, aro said:

What is the delay between the ADSB transmission and the aircraft appearing on the screen? If it's 15 seconds, the aircraft will have moved 1/4-1/2 mile or more from the displayed position. That makes it little use in the circuit. You are better off spending the time identifying the traffic out the window.

 

Well, we all agree that separation in the circuit is not its main purpose.  I'm not sure of the exact figures regarding latency (though in aircraft to aircraft transmission it shouldn't be much) but I can report that the Air Ambulance that crossed our path the other day 1000' below was exactly where and when the SkyEcho2/iPad said it would be. Otherwise we'd not have spotted it.   But for that matter, even OzRunways traffic - where you'd expect latency seems to be pretty accurate in my experience.

Edited August 26, 2021 by Garfly

[Garfly]

Anyway, as Airservices tells it :FAQ_ADS-B_DEC16.pdf

 

"Australia has adopted a single system that allows aircraft with ADS-B IN equipment to receive ADS-B OUT from all equipped aircraft without the need for ground based translator (or “rebroadcast”) stations. In our huge country, translator stations, which are necessary to make a dual system work, would be extremely expensive. Further, translator stations on the ground add another point of failure in the relaying of air traffic data."

 

And ....

 

" What use would ADS-B in a VFR aircraft be to me?

ADS-B out is a little like having taillights on your car. They are used by “the other guy”. In an environment when most aircraft have ADS-B OUT, aircraft with ADS-B IN will have the ability to “see” other aircraft that are nearby. An ADS-B IN system far exceeds the capabilities of the human eye to detect aircraft and alert you to other aircraft that are a risk. The availability of surveillance information and Flight Following services by ATC for VFR aircraft, and the availability of accurate information for SAR purposes are significant advantages too."

[Bosi72]

I've never seen/heard someone doing 360 on the base to make a separation?! Slow down or extend leg in worst case..

 

I have been in a situation when turning xwind whilst another aircraft joining xwind. Quick radio call clarified situation but it wasn't pleasant situation to be in..

 

Glad to hear no fatalities..

 

adsb is not much relevant in the circuits imo..

[Thruster88]

I dont understand the negativity toward using traffic alerts via a screen in the circuit area. It only takes a quick glance at this screen shot to see there is an aircraft turning base for runway 15. We can see where it is, where it is heading and its height relative to us. Situational awareness enhanced. Yes we need to us the radio correctly and look out but why not use every tool available.