Collision Avoidance

[shortstripper]

LOL! Sorry folks, I was about two glasses of a rather nice wine over my usual quota last night when I added my little rant Mind you, it's quite nice to vent the spleen now and then Hopefully this post won't turn into a rant also (I'm time limited so it can't really )

My rant was born of the frustration of seeing threads like this come up with monotonous regularity. The same old arguments over and over and what's worse, is that if I'm honest, it's an argument I seem to be loosing, and nobody likes to loose do they? The CAA would happily have seen everything unable to carry a transponder grounded. They lost a battle because of the PFA, BGA, BMAA ect, but I fear the war is far from over. I'm hopeful that sense has been seen, but so many pilots now seem to be blinkered into thinking that their experience of aviation is the basis for all. We could keep replacing bits from our light aircraft with "other" bits that make us more visible ... but where do we draw the line? Remove the heaviest bit (the pilot)? ............ It's OK, I am joking

I have nothing against modern technology, but until it's practical for all ... it's not really practical at all! It would be rather ironic for someone to go out and buy all the kit, only to fly smack bang into a sailplane in cloud because they assumed that all the non transponder stuff would be low down and of little risk I'm sure I heard the glider boys in Euroland had come up with a gps based avoidance system of some merit? Perhaps we're just looking at the wrong technology? Surely there must be a system that doesn't involve powerful radio transmitters, high power consumption, size and weight? I'm seriously looking at building a Thatcher CX4 as my next project. It has a much larger cockpit than my T31 and a lot more performance. I'd be quite keen to add some electrickery, but I'd prefer to use the space and weight limitations to add stuff that actually makes sense, rather than just false hope! I've had a couple of "gezzzus"! encounters before, so I'm no die hard "eye ball saves all" type, but what use is TAS, TCAS in a busy circuit where the risk is highest?

More to say, but coffee break is over

SS

[IO540]

There is no technological solution to the circuit problem, at a busy airfield. You just have to look out and hope others do the same. It's a risky place to be... Fortunately one can expect traffic to be in certain places so one can watch those. This is why I think the overhead join is stupid - several planes all head for the same spot at the same time - how clever is that?

[Rod1]

IO540,

Tolerance mode on//

“Rod, with the amount of time you have spent on here in the past telling everybody how easily you can do pilot maintenance on your permit machines, why not re-make some parts out of lighter materials, shave a few kg off the empty weight, and then you could fit a transponder.”

I have a transponder thank you! I choose to spend some of my time fighting the corner of the people who cannot fit one and trying to explain this to the CAA who listens and you lot who seem to find the concept inconvenient.

Yes I advocate regulatory systems which allow aircraft to be maintained by builder pilots. I spent 1800 hours building mine so I have a reasonable knowledge of how it fits together. There is a world of difference between building and maintaining an aircraft and designing one. My aircraft was designed by two of the best light aircraft designers in Europe. I would not even consider trying to mod it to save weight. In the whole build I registered one mod, a high intensity strobe in the tail.

soay

“So, please help me by explaining how I can improve my lookout in the situations I listed, while flying at 120 kts.”

If you really want to improve your lookout go fly gliders for a few years or get an ex member of the ROC to help you. Both would help more than trying to force 1000’s of people to fit kit which cannot be fitted to their aircraft so you can rely on electronics. You may be going at 120kn in the conditions you specify, my problem is I will be going at 138kn in the opposite direction…

Islander2

I do not think SS or I are anti tec. I have a state of the art carbon composite aircraft which is very close to my ideal flying machine. You are seeing frustration because SS could not fit a mode s transponder to his machine; it is just not technically possible to do it given current tec. I have spent 100’s of hours on the Mode s campaign along with many others. The CAA started out with “everyone must fit mode s” and finished up agreeing this was not technically possible. I realize that is inconvenient, as mandatory transponders and TCAS would be very convenient for you, but it is not going to happen. I say this not from the point of view of being anti tec, but from the point of view that the majority of flying machines cannot fit the devices.

I am genuinely astounded at the lack of knowledge of the lighter end of GA exhibited by some of the postings on this thread. It is a shame we cannot all get together at some suitable airfield. A good look round SS excellent machine would soon convince you we are not making the technical issues up, as would a look at the w&b of a Eurostar or CT.

Tolerance mode off//


Rod1

[soay]

[Tolerance of condescension mode on]

Originally Posted by Rod1

If you really want to improve your lookout go fly gliders for a few years or get an ex member of the ROC to help you.

That would not help much with the issues of blind spots and relative speeds that I'm concerned about.

Originally Posted by Rod1

The CAA started out with “everyone must fit mode s” and finished up agreeing this was not technically possible. I realize that is inconvenient, as mandatory transponders and TCAS would be very convenient for you, but it is not going to happen. I say this not from the point of view of being anti tec, but from the point of view that the majority of flying machines cannot fit the devices.

Could a remote mount transponder be a technological solution to the problem in the lightest powered aircraft? There should be space for an on/off switch on any panel, which would suffice if the unit only squawked a fixed code. That code should be reserved for such devices, so that ATC would know their limitations. The market for such a transponder must be larger than that for the GTX330, so it shouldn't be too hard to persuade a manufacturer to make them, and the extra simplicity should reduce cost and weight.

[Tolerance of condescension mode off]

[ShyTorque]

I certainly don't agree with anyone being grounded because their aircraft is incapable of carrying certain new equipment; I don't personally think the CAA would succeed in making that happen, nor should they try.

On the other hand, as a flyer, I have a moral and legal responsibility to keep safe both my passengers and do my utmost to minimise the risk to those flying in the same airspace as myself. I use an ATC service wherever possible, I also use my TAS as effectively as I can to enhance my lookout scan. Those folk with a transponder fitted get a much better chance of me being aware of their presence in advance (often 10 miles or more) and my avoiding them by a good margin. Those without a transponder don't get that extra protection factor; both myself and the other pilot have to rely on the Mk1 eyeball, with all it's limitations, it's as simple as that.

My eyesight is good enough to see a light aircraft about 4 or five miles away in good average conditions, unfortunately that is about the limit of human visual acuity, Beyond that the "target" is simply too small - our eyes weren't designed to do any more than that. Possibly when we evolved as "hunter gatherers" an animal further away than that was too far away to chase - we'd be cream crackered by the time we got to it.

It's not too uncommon for my TAS and/or ATC tells me an aircraft is very close by but try as hard as I can, I just can't see the damned thing, often because it's a very small aircraft with insufficient colour or brightness contrast to the background. In these cases, I put on all four landing lights and hope the other pilot sees me . This possibly irritates some pilots, but at least he's seen me if he's irritated .

Since I began flying TCAS/TAS equipped aircraft nine years ago (28 years prior to that without the benefit), I have become aware just how busy our lower airspace is becoming; far more busy than when I began flying gliders some years ago. Just like our roads are so much busier and more dangerous these days. Back in the early 1970s I also protested against the mandatory wearing of a helmet whilst riding a motorcycle (even though I already chose to wear one myself and knew it made good sense).

I do think that transponders and TCAS / TAS are very good bits of kit to have, much better than seat belts in cars or crash hats on motorcycles because they can, in many cases, help to prevent an accident, rather than try to minimise the after-effects to the individuals involved!

SS, I can't really agree with your example of the unseen sailplane in cloud as an argument against the fitting conspicuity equipment, surely it is an argument FOR fitting it to all aircraft that operate in IMC? Actually, this was the basis of another discussion here some time ago (which went on for ages)! At least one glider pilot voiced the opinion that everyone should fly around on "his" glider frequency whilst in IMC, even to the detriment of obtaining an ATC service elsewhere, just in case he might be gliding in cloud, which he rarely did, on his day off.

[vee-tail-1]

Dear oh dear! been away for a bit and this thread has become vitriolic.
Everyone agrees lookout is vital but not 100% (or even 50%) effective.
Surely strobes, lights, LEDs, could make a significant difference in the most dangerous situations.... weekends, haze, low level, lots of non transponding a/c etc?
I have been looking at the lights available, and there seems no way of comparing them. Aircraft Spruce sometimes quote "candles", or say "gives high intensity flash". Other manufacturers quote "very bright" or "best on the market". Some suggest that "alternating dual flashing white strobes" are the way to be seen.
Back to basics, and a simple a/c with an alternator giving say 2 to 3 amps of 12 volt DC power... What system could be fitted to give the maximum visibility and enhanced safety?

[BackPacker]

Could a remote mount transponder be a technological solution to the problem in the lightest powered aircraft? There should be space for an on/off switch on any panel, which would suffice if the unit only squawked a fixed code. That code should be reserved for such devices, so that ATC would know their limitations. The market for such a transponder must be larger than that for the GTX330, so it shouldn't be too hard to persuade a manufacturer to make them, and the extra simplicity should reduce cost and weight.

My guesstimate is that the problem is not in the physical size of the unit, but in the power consumption and hence the size of the battery in a non-electric aircraft.

Is there anybody who has more knowledge of electronics than me, who can do a few calculations based on power output, transmission losses etc. and come up with the size of a battery that can support a mode S transponder for a reasonable flight time (say eight hours - I understand that for a Silver C in gliding you have to do a five-hour flight)

[Whirlygig]

I'd have thought the solution was simple; make it mandatory for all aircraft to wear a hi-vis vest!

Cheers

Whirls

[shortstripper]

SS, I can't really agree with your example of the unseen sailplane in cloud as an argument against the fitting conspicuity equipment, surely it is an argument FOR fitting it to all aircraft that operate in IMC? Actually, this was the basis of another discussion here some time ago (which went on for ages)! At least one glider pilot voiced the opinion that everyone should fly around on "his" glider frequency whilst in IMC, even to the detriment of obtaining an ATC service elsewhere, just in case he might be gliding in cloud, which he rarely did, on his day off.

ST

I wasn't using that example as an argument against anything. It was to illustrate the danger of assuming that non transponding aircraft are likely to be low and slow and in VMC.

I'm still amazed that nothing small and lightweight can't be thought of. What BackPacker suggests would be fine ... BUT NOBODY HAS INVENTED ONE! When they do, or they develope a better system, I'll sign up straight away. I'm not so stupid as to gamble with my own life just to make a point. I'd love a foolproof avoidance system that I could fit. As it stands, no such system exists

SS

[Rod1]

VT1

Your best bet is to visit a few busy airfields and look at the strobes in use. I fitted a high intensity strobe to the tail of my machine. This was on the basis that I stood a chance of seeing stuff coming at me from the front but people overtaking me from the rear was the big problem. The strobe uses solid state tec and consumes a max of 2a. It is very bright on the ground, but has proved to be of very little use in the air.

The number of mid air collisions in the UK is very small. This thread has, to some extent, made it seem that we all bump into each other every day. I have had a number of close encounters, but most have been in the circuit.

Rod1

[mm_flynn]

Originally Posted by BackPacker

My guesstimate is that the problem is not in the physical size of the unit, but in the power consumption and hence the size of the battery in a non-electric aircraft.

Is there anybody who has more knowledge of electronics than me, who can do a few calculations based on power output, transmission losses etc. and come up with the size of a battery that can support a mode S transponder for a reasonable flight time (say eight hours - I understand that for a Silver C in gliding you have to do a five-hour flight)

The Trig mode-S seems to draw 6w (about .5 amp in a 14v aircraft), so if you wanted to have a 10 hour capacity you would need 60Whr of battery, A Lithium Ion battery would need to be about 0.4kg of battery (or about 10 digital camera batteries).

I am sure IO has also measured power consumption on his 330 and come up with a number not dissimilar.

[BackPacker]

The Trig mode-S seems to draw 6w (about .5 amp in a 14v aircraft), so if you wanted to have a 10 hour capacity you would need 60Whr of battery, A Lithium Ion battery would need to be about 0.4kg of battery (or about 10 digital camera batteries).

That is actually much better than I suspected. For reference, the car battery in my VW diesel is 70 Ah. Theoretically that would supply enough juice for 140 hours of operation.

Although I am a bit suspicious: The Trig brochure claims 240 watt nominal power output at the antenna connector. That power has to come from somewhere and with losses and everything suggests a power draw of 300-400W. Obviously that's burst power in response to an interrogation but it does mean that the busier the area is, radar-wise, the more responses are required (selective interrogation helps a lot here, obviously) and the more the power draw goes up. And I believe TCAS does active interrogation as well, don't they? Instead of relying on scatter from transponders in a radar environment?

It would be nice to hear what the impact of being in a busy radar environment is on power consumption. Nevertheless, I'm impressed with the numbers and I've got the feeling that power consumption therefore should not be an issue in creating a portable/rechargeable transponder of a size not much larger than, let's say, a milk carton, batteries and everything included. Make it robust enough and you could even argue that parachutists should be taking one with them.

[mm_flynn]

Re - Parachutists and plastic planes - you still have the problem of a ground plane for the antenna and the fried nadgers issue.

I think you will find that the 250W reply transmitter is on for about 1.6% of time the transponder is actually being interrogated. Assuming the SSR beam width is 3-4 degrees, a given ground station will illuminate a transponder for about 1% of the time. Therefore the 250W output is only needed for about 0.016% of the time, and is therefore a vanishingly small amount of the power requirement.

[BackPacker]

Re - Parachutists and plastic planes - you still have the problem of a ground plane for the antenna and the fried nadgers issue.

I thought parachutists were required to have balls of steel?

[shortstripper]

I thought parachutists were required to have balls of steel?

Great for pulling power! Balls of steel and induced magnetism thrown in for free!

SS

[IO540]

It would be easy enough to run say a GTX328/330 from a laptop-style LIPO battery.

As mm_flynn explains, the transmission duty cycle is miniscule and this also deals with the much advertised health hazard; this isn't a mobile phone which - in a poor signal area - can be radiating as much as 0.4W 100% of the time, and be doing it right up against the side of your head.

Rod1 - how is the empty weight of your homebuilt made up? % due to engine, airframe, avionics, etc. It should be trivial to save 5-10kg by replacing certain non-structural items. I realise you carry a transponder but you gave this example as representing huge numbers of pilots.

On the topic of not understanding homebuilt capabilities, I do know full well that just about anything with an IC engine can reach at least 10,000ft. The question is: how often is this used? The issue in all "mid-air" debates is the statistical likelihood of an encounter, and my experience (~ 900hrs) firmly confirms that large chunks of GA do fly very low. To a large degree, the 0-1000ft AGL band is a fair game (full of various flying lawn-mowers, helicopters, towers, etc, and with ineffective radar service due to terrain) and if you fly there you should accept the greatly reduced safety (albeit still a very low mid-air probability). It is above that which I am not happy with.

[scooter boy]

"the overhead join is stupid - several planes all head for the same spot at the same time - how clever is that?"

How right you are!
Ban the overhead join I say.

SB

[BackPacker]

It would be easy enough to run say a GTX328/330 from a laptop-style LIPO battery.

The other issue is certification of course. Does the CAA/JAA/ICAO allow a solution where, say, you have a plumbed-in antenna but possibly a removable transponder and definitely a removable, rechargeable battery? Because that would seem like the obvious solution in a glider or other non-electric airplane.

I can see a few things where this might be a problem:
- Source of static pressure needs to be calibrated and you need to extend your current static pressure plumbing to fit a quick-connect to which to connect the transponder. Simply taking cabin air as static pressure won't always work. Although I don't know the required accuracy of the FL encoding in the transponder signal. It might be so that the variation between cabin pressure and static pressure is less than the accuracy required for the transponder signal.
- Quick connectors in various places may corrode, particularly to the plumbed-in antenna, leading to degradation of the signal. And what I understand is that devices like Zaon makes, derive part of their solution from the power output from the transponder so even a minor signal loss might lead to solutions that are way off.
- It would make sense to have an indication of battery charge somewhere, and a warning when battery voltage drops below a certain critical threshold. The current breed of transponders, intended for aircraft with an electric circuit, don't incorporate these.
- The transponder itself might end up in the wrong airplane - think a gliding school with dozens of planes and dozens of transponders to recharge every day. Something is bound to go wrong, leading to wrong flight IDs and ICAO IDs to be transmitted.

[Fuji Abound]

I have a few comments having caught up on this thread.

See and avoid.

It is a nice idea. However, there have been a number of studies that suggest at best it works poorly. I have posted before the times we typically have to spot another - they are quite sobering, particularly if you factor in our reaction time (which we usually forget about).

The truth is the majority of the time collision avoidance is down to "good luck".

I am sure we can all recall on a busy days when we have been receiving traffic how little of the reported traffic we actually see.

Avoidance.

There are a number of good strategies to reduce the risk of collision. The usual suspects are to fly as high as possible (there is far less traffic), to think about choke points caused by CAS, navigation or terrain, and, best of all, leave the landing light on in conditions of poor visibility.

PCAS.

I am pretty much convinced the system works well most of the time. The more basic of the units is still very useful even though it does not give you the direction of the traffic. The key here is that it will warn you if traffic enters a "protected bubble" around your aircraft. It displays the vertical separation. If traffic enters this bubble you climb or descend to ensure a vertical separation is maintained.

The systems provides an audible warning so there is no need alter your head out of the cockpit time.

All in all, keeping a good look out can do no harm, with luck you might avoid an aircraft by doing so, PCAS adds, for a very small cost, an additional (and in my opinion significant) margin of safety which combined with defensive flying and receiving a RIS whenever possible all help to reduce the risk of a collision significantly.

Should all aircraft carry a transponders?

I was for many years opposed. It is important to protect our rights and to recognise the problems fitting a transponder to some aircraft and gliders. As the cost of these units has fallen I find it more difficult to justify exempting some aircraft, whilst appreciating that in some cases cost is not the only factor.

I would guess that if there was a market a portable transponder that only squawks 7000 would be cheap to produce and could be made so it was both portable and could be powered by a self contained NiCad. If the purpose of a transponder in the more "basic" aircraft is only to enable the transponder to be interrogated for collision avoidance and the pilot has no intention of operating within CAS this would seem a very simple solution.

[ChampChump]

Well, how about everyone calms down and fits a nice big high visibility jacket to their aircraft? Yes the cloak of invincibility....

I'd have thought the solution was simple; make it mandatory for all aircraft to wear a hi-vis vest!

I guess great minds think alike...