PCAS collision avoidance
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PCAS collision avoidance
I heard yesterday about the tragic collision between two RAF Tutors, killing two instructors and two young air cadets. I recall hearing about one or more midairs last year as well.
A large number of aircraft are now fitted with transponder equipment. Because of the number of ground stations and commercial air traffic, this equipment will be interrogated regularly. PCAS units (passive collision avoidance) would therefore function well if used sensibly by pilots.
Both the Tutors were fitted with thousands of pounds worth of transponding equipment, which was useless to them because they did not have a 300-pound gizmo fitted.
I would like to hazard a guess that in most airproxes between 2+ seat aircraft, at least 1 aircraft has a transponder. Therefore, the collision could be avoided with a simple, comparatively cheap unit which every pilot could carry - it runs on AA batteries.
The accepted position of GA on any cost related issue is to put its fingers in its ears and dig its heels in. Why, this time, don't we be proactive and invest in the technology which could have saved two young lives, and those of their pilots? Even, dare I say it, pressure the CAA in to making it mandatory, so if your aircraft has a transponder, then you know that everyone else will see you?
A large number of aircraft are now fitted with transponder equipment. Because of the number of ground stations and commercial air traffic, this equipment will be interrogated regularly. PCAS units (passive collision avoidance) would therefore function well if used sensibly by pilots.
Both the Tutors were fitted with thousands of pounds worth of transponding equipment, which was useless to them because they did not have a 300-pound gizmo fitted.
I would like to hazard a guess that in most airproxes between 2+ seat aircraft, at least 1 aircraft has a transponder. Therefore, the collision could be avoided with a simple, comparatively cheap unit which every pilot could carry - it runs on AA batteries.
The accepted position of GA on any cost related issue is to put its fingers in its ears and dig its heels in. Why, this time, don't we be proactive and invest in the technology which could have saved two young lives, and those of their pilots? Even, dare I say it, pressure the CAA in to making it mandatory, so if your aircraft has a transponder, then you know that everyone else will see you?
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The problem with the £300 one is that it doesn't tell you the azimuth (heading) of the conflicting traffic.
To get the one which gives you some idea, it is the £1000 one.
But all these are - for paperwork / regulation reasons - portable cigar-lighter-plug type things which IMHO put a lot of people off because you end up with the power lead strung across messily the instrument panel.
If one could fit the £1000 one somewhere neatly, that would be something else, but there is no legal way to do it because it is not certified for a permanent installation (not in a G-reg, for sure).
A proper installed system starts at around £10k, but is rendered much less than useful by the number of planes whose pilots are exercising their free citizen's privileges and flying with transponders turned off.
To get the one which gives you some idea, it is the £1000 one.
But all these are - for paperwork / regulation reasons - portable cigar-lighter-plug type things which IMHO put a lot of people off because you end up with the power lead strung across messily the instrument panel.
If one could fit the £1000 one somewhere neatly, that would be something else, but there is no legal way to do it because it is not certified for a permanent installation (not in a G-reg, for sure).
A proper installed system starts at around £10k, but is rendered much less than useful by the number of planes whose pilots are exercising their free citizen's privileges and flying with transponders turned off.
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It brings it home to you how inadequate see and avoid is, when it fails so tragically for two experienced RAF pilots. I'd support any proposal to make mode C mandatory in all powered aircraft with electrical systems. That should encourage the take up of collision avoidance systems, and so reduce their prices.
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... but the problem remains PCAS only detects transponding aircraft. You may end up coming into conflict with a Luscombe (see AAIB Feb report) or Jodel without a power source for a Tx and PCAS - both power-hungry.
I tried the £300 one coming out of the PFA Rally some years ago. The sky was black with departing aircraft but not a squeak from the PCAS, which burned through the batteries in very short order.
When aircraft are outside CAS there is no requirement to be on radio or they might even have been talking to different operators. The Luscombe incident makes it clear that even if they had asked for a LARS service, it wasn't available.
Lookout isn't perfect by any manner of means, but often it's all we have.
I tried the £300 one coming out of the PFA Rally some years ago. The sky was black with departing aircraft but not a squeak from the PCAS, which burned through the batteries in very short order.
When aircraft are outside CAS there is no requirement to be on radio or they might even have been talking to different operators. The Luscombe incident makes it clear that even if they had asked for a LARS service, it wasn't available.
Lookout isn't perfect by any manner of means, but often it's all we have.
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Does anyone else have experience of how well the units work?
On the point of it not providing bearing info - I would hope that if a unit told you that there was traffic nearby then you would find it visually, regardless of what info it gave - and that range and altitude would be sufficient for this. If it is out of line of sight behind the aircraft, then odds on it won't be a threat in most cases, at it will either see you ahead, or have insufficient speed to catch up.
I have seen euipment on sale for installing in a panel and hooking up to the electrical supply for the 300-pound set.
In the case of the two Tutors yesterday, they would very probably have been in range of a ground station interrogating their transponders, and therefore the equipment would probably have prevented this tragic accident from happening.
On the point of it not providing bearing info - I would hope that if a unit told you that there was traffic nearby then you would find it visually, regardless of what info it gave - and that range and altitude would be sufficient for this. If it is out of line of sight behind the aircraft, then odds on it won't be a threat in most cases, at it will either see you ahead, or have insufficient speed to catch up.
I have seen euipment on sale for installing in a panel and hooking up to the electrical supply for the 300-pound set.
In the case of the two Tutors yesterday, they would very probably have been in range of a ground station interrogating their transponders, and therefore the equipment would probably have prevented this tragic accident from happening.
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Flarm would also have almost certainly helped avoid this, but GA is apparently largely in ignorance of it or resolutely against fitting it, even though many GA pilots continually complain about gliders being a collision hazard, and UK gliders are getting Flarm in increasing numbers.
(Unlike PCAS, Flarm alerts when a collision is likely i.e. converging tracks, not just another unit in the vicinity which may not be a threat; and it shows the direction of the threat. It does not alert nearby but not converging track units.)
Same arguments as PCAS re wires etc., however – it would for most people be a portable piece of equipment, needing a battery supply or lead to a lighter socket or something.
As I have posted several times before, GA power/power collisions are more frequent than GA/CAT (civil air transport - thankfully none yet in the UK) or unrelated power/glider (only about 4 in the last 30 years).
Regarding wider use of FLARM, my personal opinion is that for the UK, use by gliders will increase slowly from a few per cent to a significant proportion, when the critical mass will be perceived as being large enough to encourage most glider pilots to use it. Unless something better comes along for powered GA, I think it quite possible that the same thing would happen, with the timing a few years later. I suspect that the middle phase, rapid increase in use once a critical mass is reached, will happen because those without will be shown how many more aircraft they can’t see that are in fact detectable. Just my opinion.
see Flarm - Homepage
(No commercial relationship with Flarm, just a customer).
Chris N.
(Unlike PCAS, Flarm alerts when a collision is likely i.e. converging tracks, not just another unit in the vicinity which may not be a threat; and it shows the direction of the threat. It does not alert nearby but not converging track units.)
Same arguments as PCAS re wires etc., however – it would for most people be a portable piece of equipment, needing a battery supply or lead to a lighter socket or something.
As I have posted several times before, GA power/power collisions are more frequent than GA/CAT (civil air transport - thankfully none yet in the UK) or unrelated power/glider (only about 4 in the last 30 years).
Regarding wider use of FLARM, my personal opinion is that for the UK, use by gliders will increase slowly from a few per cent to a significant proportion, when the critical mass will be perceived as being large enough to encourage most glider pilots to use it. Unless something better comes along for powered GA, I think it quite possible that the same thing would happen, with the timing a few years later. I suspect that the middle phase, rapid increase in use once a critical mass is reached, will happen because those without will be shown how many more aircraft they can’t see that are in fact detectable. Just my opinion.
see Flarm - Homepage
(No commercial relationship with Flarm, just a customer).
Chris N.
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I do not know what the cause of the RAF Tutors accident was, but there is a possibility they were formation flying so PCAS would have been irrelevant.
If you take the recent AAIB report on the Staffordshire mid air (See separate thread) then you get an interesting picture. The vintage aircraft spotted the Micro, took avoiding action and was collected by a turboprop. The vintage machine and the micro had no transponder and there was no radar service available in the area. If the turboprop had had PCAS it would have failed to see either of the other aircraft, but see and avoid avoided the potential conflict between the vintage machine and the micro.
I fly from the same strip and the vintage machine and about 80% of locally based flying machines are not transponder equipped. It if far more likely that I will fit FLARM than PCAS.
Rod1
If you take the recent AAIB report on the Staffordshire mid air (See separate thread) then you get an interesting picture. The vintage aircraft spotted the Micro, took avoiding action and was collected by a turboprop. The vintage machine and the micro had no transponder and there was no radar service available in the area. If the turboprop had had PCAS it would have failed to see either of the other aircraft, but see and avoid avoided the potential conflict between the vintage machine and the micro.
I fly from the same strip and the vintage machine and about 80% of locally based flying machines are not transponder equipped. It if far more likely that I will fit FLARM than PCAS.
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soay:
I presume like everyone else you don't actually know (a) what these aircraft were doing when they collided, (b) whether they knew of each other's presence, (c) whether the pilots were RAF (not all AEF pilots are) and (d) how experienced they were. So I think drawing conclusions about the efficacy of see and avoid may be a tad premature.
NS
It brings it home to you how inadequate see and avoid is, when it fails so tragically for two experienced RAF pilots
NS
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I do not know what the cause of the RAF Tutors accident was, but there is a possibility they were formation flying so PCAS would have been irrelevant.
Flarm is basically a 576 Euro TCAS box for us little guys.
Two bureaucratic obstacles to Flarm:
Sure beats putting Mode S in everything that flies when radars and transponders are on their way to being superceded by ADSB
Two bureaucratic obstacles to Flarm:
- Not Invented Here as far as ICAO is concerned -- TCAS will have to be pried out of their dead fingers
- The manufacturer refuses to sell in North America because of product liability issues
Sure beats putting Mode S in everything that flies when radars and transponders are on their way to being superceded by ADSB
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As to whether the Tutors were flying in formation, I would say almost certainly no - formation flying in AEF, due to the presence of civillians on board, is usually an absolute no-no.
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PCAS works fine
I have had one of the £1,000 units (Zaon) for around 18 months and found it works very well. It gives approx range., approx heading and altitude w/altitude trend, plus an audible alert 'Traffic' in the headset if something is near.
It is a minor pain having to put it in the rental aircraft with wires each time, but there have been enough times it has alerted me to close traffic - which I have not seen before the alert - that I would not want to fly without it.
Of course, you look out as best you can but you are bound to not see some other aircraft.
Obviously it does not pick up everything - only those with transponder on - but I would rather be alerted to at least some of the other aircraft than none of those that my Mk1 eyeball has not spotted.
It is a minor pain having to put it in the rental aircraft with wires each time, but there have been enough times it has alerted me to close traffic - which I have not seen before the alert - that I would not want to fly without it.
Of course, you look out as best you can but you are bound to not see some other aircraft.
Obviously it does not pick up everything - only those with transponder on - but I would rather be alerted to at least some of the other aircraft than none of those that my Mk1 eyeball has not spotted.
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http://www.aaib.gov.uk/cms_resources...AY%2002-09.pdf
from the AAIB report into the mid air collision in December 2007
"Following the accident to G-AKUI and ZK-KAY, AAIB investigators discussed mid-air collisions involving recreational aircraft, and electronic conspicuity, with staff at the CAA’s Directorate of Airspace Policy. The Directorate staff explained that, although they perceived a widespread concern about mid-air collisions amongst participants in recreational aviation, they were also aware of strong opposition from aircraft owners to mandatory requirements to fit transponders, on the grounds of complexity, cost, and weight. For these reasons, proposals to mandate widespread carriage of Mode S transponders had been withdrawn, and more limited proposals had been put forward for consultation. These proposals did not amount to an effort to reduce the collision risk between recreational aircraft, but only to protect aircraft operating inside controlled airspace from collision with recreational aircraft."
Whilst this is the mentality, there will always be collisions between recreational aircraft.
The human eyeball is simply not enough for collision avoidence
from the AAIB report into the mid air collision in December 2007
"Following the accident to G-AKUI and ZK-KAY, AAIB investigators discussed mid-air collisions involving recreational aircraft, and electronic conspicuity, with staff at the CAA’s Directorate of Airspace Policy. The Directorate staff explained that, although they perceived a widespread concern about mid-air collisions amongst participants in recreational aviation, they were also aware of strong opposition from aircraft owners to mandatory requirements to fit transponders, on the grounds of complexity, cost, and weight. For these reasons, proposals to mandate widespread carriage of Mode S transponders had been withdrawn, and more limited proposals had been put forward for consultation. These proposals did not amount to an effort to reduce the collision risk between recreational aircraft, but only to protect aircraft operating inside controlled airspace from collision with recreational aircraft."
Whilst this is the mentality, there will always be collisions between recreational aircraft.
The human eyeball is simply not enough for collision avoidence
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From the above aaib report
Electronic conspicuity and collision prevention
Electronic conspicuity involves the carriage and operation of devices such as transponders and ‘FLARM’ (a device developed initially for gliders). These devices make aircraft ‘electronically conspicuous’ to other aircraft which are equipped with the means of detection of, or interaction with, the equipment on the subject aircraft. These systems require electric power and the fitting of wiring and antennae, which demand spare capacity from the aircraft’s power sources; they also add weight to the aircraft.
Aircraft owners may fit equipment such as TCAS, transponder proximity receivers, and FLARM, which assist their pilots in gaining awareness of other aircraft around them, and, in the case of TCAS, provide guidance to assist in avoiding collisions. Some lightweight devices are available, including some which carry their own battery power supplies.
TCAS is in very limited use in recreational aircraft, transponder proximity receivers are used by a small number of pilots, and FLARM, although gaining popularity amongst glider pilots, is finding less widespread acceptance outside gliding. It is widely accepted that the introduction of TCAS in commercial air transport aircraft has markedly reduced the probability of collision involving a TCAS-equipped aircraft and another transponding aircraft
Electronic conspicuity involves the carriage and operation of devices such as transponders and ‘FLARM’ (a device developed initially for gliders). These devices make aircraft ‘electronically conspicuous’ to other aircraft which are equipped with the means of detection of, or interaction with, the equipment on the subject aircraft. These systems require electric power and the fitting of wiring and antennae, which demand spare capacity from the aircraft’s power sources; they also add weight to the aircraft.
Aircraft owners may fit equipment such as TCAS, transponder proximity receivers, and FLARM, which assist their pilots in gaining awareness of other aircraft around them, and, in the case of TCAS, provide guidance to assist in avoiding collisions. Some lightweight devices are available, including some which carry their own battery power supplies.
TCAS is in very limited use in recreational aircraft, transponder proximity receivers are used by a small number of pilots, and FLARM, although gaining popularity amongst glider pilots, is finding less widespread acceptance outside gliding. It is widely accepted that the introduction of TCAS in commercial air transport aircraft has markedly reduced the probability of collision involving a TCAS-equipped aircraft and another transponding aircraft
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from the AAIB report into the mid air collision in December 2007
"Following the accident to G-AKUI and ZK-KAY, AAIB investigators discussed mid-air collisions involving recreational aircraft, and electronic conspicuity, with staff at the CAA’s Directorate of Airspace Policy. The Directorate staff explained that, although they perceived a widespread concern about mid-air collisions amongst participants in recreational aviation, they were also aware of strong opposition from aircraft owners to mandatory requirements to fit transponders, on the grounds of complexity, cost, and weight. For these reasons, proposals to mandate widespread carriage of Mode S transponders had been withdrawn, and more limited proposals had been put forward for consultation. These proposals did not amount to an effort to reduce the collision risk between recreational aircraft, but only to protect aircraft operating inside controlled airspace from collision with recreational aircraft."
Whilst this is the mentality, there will always be collisions between recreational aircraft.
"Following the accident to G-AKUI and ZK-KAY, AAIB investigators discussed mid-air collisions involving recreational aircraft, and electronic conspicuity, with staff at the CAA’s Directorate of Airspace Policy. The Directorate staff explained that, although they perceived a widespread concern about mid-air collisions amongst participants in recreational aviation, they were also aware of strong opposition from aircraft owners to mandatory requirements to fit transponders, on the grounds of complexity, cost, and weight. For these reasons, proposals to mandate widespread carriage of Mode S transponders had been withdrawn, and more limited proposals had been put forward for consultation. These proposals did not amount to an effort to reduce the collision risk between recreational aircraft, but only to protect aircraft operating inside controlled airspace from collision with recreational aircraft."
Whilst this is the mentality, there will always be collisions between recreational aircraft.
These include cost (up to £5k to fit a Mode S when the aircraft might be worth less than that) and practicality (no power source or battery life less than the length of a day's flying. There is little gain in safety except for the very short period when a commercial aircraft flies in areas where GA is prevalent - Class G. GA gets very little from that.
We were promised by the CAA a low-cost, low-powered Tx but this is years away. Add to that the cost of a PCAS and and that would wreck any idea of low-end aviation.
Don't ever think that we are hostile to appropriate use of technology - in the case of the Luscombe fatality, the pilot died, while the bigger aircraft landed successfully. It is likely to be the smaller aircraft that will come off worse.
But given that the ATSOCAS services are variable, carrying expensive kit will not give much in the way of safety. Look at the proposal for Jersey Zone, for example. In future when you ask for a Traffic Service it will be downgraded to a Basic Service - ie non-radar derived information.
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Look at the proposal for Jersey Zone, for example. In future when you ask for a Traffic Service it will be downgraded to a Basic Service - ie non-radar derived information.
Is the proposal to downgrade the class A?
I totally missed whatever it is you're refering to. A link would be much appreciated
dp
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Originally Posted by NorthSouth
Originally Posted by soay
It brings it home to you how inadequate see and avoid is, when it fails so tragically for two experienced RAF pilots
Flying Officer Hylton Price was a retired wing commander who was part of the RAF voluntary reserves and an experienced instructor. He was a former Tornado and Phantom jet pilot.
Flt Lt Andy Marsh, who had "excellent flying skills", was only promoted last week and was waiting to start advanced fast jet training at Raf Valley.
Gp Capt Andy Naismith said that there were "very strict rules" to ensure planes did not fly too close together.
Seems likely that they were better pilots than most of us, but still did not see each other.
This would not surprise anyone who's flown with TCAS, or a radar information service, because of the number of times you're warned of aircraft that you can't see - even though you've been informed where to look.
Avoid imitations
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This would not surprise anyone who's flown with TCAS, or a radar information service, because of the number of times you're warned of aircraft that you can't see - even though you've been informed where to look.
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I am surprised given past discussion on this issue some of the misconception here.
Zaon Pcas units are the ones we talk about. There are two versions. The difference is the more expensive one indicates the compass quarter in which to look.
Having used both units alongside Skyforce CAS I can report that their accuracy is outstanding.
Both units give a range and altitude difference. This means it is relatively easy to determine if traffic is getting closer and is at the same height. There maybe sound theoretical grounds for not reacting to traffic you cant see, however if the traffic is getting closer and is the same height adjusting to ensure vertical seperation has in my experience always avoided a conflict whether or not I could see the traffic.
It is interesting to note on how many occasions you never see the traffic or when you do just how close it is. Knowing the quarter in which to look to spot the traffic is a benefit but I am not convinced the benefit is as significant as you might believe.
The cheaper PCAS unit is self contained. It runs on two AA batteries for at least four hours. There are no trailing wires. It is easy to stick to almost anything. The more expensive unit does require an external power source but it is easy to connect a small battery pack.
All these systems rely on the other aircraft transponding. I am constantly surprised by how many are, particularly the higher you are and the worse the weather. You are inevitably most at risk low level on a sunny day!
In my view these systems significantly reduce the risk of a mid air. They are not a substiute for maintaining a good look out nor do they detract in any way from doing so.
Zaon Pcas units are the ones we talk about. There are two versions. The difference is the more expensive one indicates the compass quarter in which to look.
Having used both units alongside Skyforce CAS I can report that their accuracy is outstanding.
Both units give a range and altitude difference. This means it is relatively easy to determine if traffic is getting closer and is at the same height. There maybe sound theoretical grounds for not reacting to traffic you cant see, however if the traffic is getting closer and is the same height adjusting to ensure vertical seperation has in my experience always avoided a conflict whether or not I could see the traffic.
It is interesting to note on how many occasions you never see the traffic or when you do just how close it is. Knowing the quarter in which to look to spot the traffic is a benefit but I am not convinced the benefit is as significant as you might believe.
The cheaper PCAS unit is self contained. It runs on two AA batteries for at least four hours. There are no trailing wires. It is easy to stick to almost anything. The more expensive unit does require an external power source but it is easy to connect a small battery pack.
All these systems rely on the other aircraft transponding. I am constantly surprised by how many are, particularly the higher you are and the worse the weather. You are inevitably most at risk low level on a sunny day!
In my view these systems significantly reduce the risk of a mid air. They are not a substiute for maintaining a good look out nor do they detract in any way from doing so.
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Until flarm stop having anticompetitive, locking-in, unethical business practices they can sell their stuff to themselves.
They have at least on death, a friend of mine, on their shoulders. Don't ask me for details, but if they weren't such a bunch of bastards, there is a chance he would be still alive.
...
They have at least on death, a friend of mine, on their shoulders. Don't ask me for details, but if they weren't such a bunch of bastards, there is a chance he would be still alive.
...