Besides, the numbers are wrong. 20M is not 20 times more than 22M.
Just to make note of it, the presentation of the data is confusing but the numbers are only wrong by about 5%. The stated UK average is about 1 million hours per year. The US average is about 21 million hours per year. The ratio is therefore about 21 not 20.
The point about relative land areas is a good one, but I think what matters is the traffic density in areas where people fly, not in the countries as a whole. The US and UK are comparable in that they have a lot of traffic in specific areas and not so much in others but I’d guess that the average GA plane in the US is more often in close proximity to other planes – because although the US has 21 times the traffic in 40 times the land area, it also has a very large proportion of land with very few people and therefore little activity.
Googled it, and according to statistical mechanics, the number of collisions (of molecular particles) is proportional to the number of particles per unit volume. It’s reasonable to assume that aircraft who don’t know or see each other behaves in a random fashion, like particles, with regard to each other.
Considering the flight is done on average at equal AGL for the US and the UK, it is therefore reasonable to conclude that the number of collisions is directly proportional to the aircraft density, or flight hours per area. And this is what the number shows. The “discrepancy” of 1.24 vs 1.0 can simply be prescribed to the average flight level is higher in the US, by a factor 1.24. Or a whole bunch of other factors, including statistical error.
The 1/4 MAC rate in the US versus UK is purely a fact of nature. There’s nothing more to it. Exchange all the aircraft with flying elephants, and we will see the exact same result 
Silvaire wrote:
Just to make note of it, the presentation of the data is confusing
Yes, fooled me. This whole (grossly bogus) thing is obviously made by someone for a particular purpose, like “further studies”, not only in the UK but “other European countries”
LeSving wrote:
Googled it, and according to statistical mechanics, the number of collisions (of molecular particles) is proportional to the number of particles per unit volume. It’s reasonable to assume that aircraft who don’t know or see each other behaves in a random fashion, like particles, with regard to each other.
This can’t be right. Let’s assume you had N particles and each particle on average collided with A particles per second, so total number of collisions was N*A per second. If you multiplied the number of particles by 10 it would be 10N particles and each would collide with 10A particles per second, so total number of collisions goes up by a factor of 100. So, it’s a quadratic relation, not linear.
Statistics aside, the US doesn’t have the ‘standard overhead join’, which seems designed to promote mid-air collisions.
Other than that, I think the land area is largely irrelevant. Most GA traffic in the US occurs in relatively few places, such as SoCal, Florida and the NY area. ADS-B really has been a game changer, it can actually be quite scary to see all the targets! Not sure if you can with a European sub, but zoom in on the LA area in ForeFlight and enable the traffic layer.
In the US versus UK comparison there are 21 times as many flight hours in 40 times the land area. The flight hours per unit land area is therefore 1.9 times as high in the UK, but the collision rate per hour is apparently about 4 times higher. So on that basis the airborne collision problem is about twice as bad in the UK.
Note that the US land area includes e.g. Alaska and states like Wyoming, areas with almost nobody there is doing anything near other people, including flying. Flying hours are in reality concentrated in places like Florida and California. The UK also has areas with concentrated flying but I don’t believe with the same level of geographic concentration as exists in the US.
YakovD wrote:
This can’t be right. Let’s assume you had N particles and each particle on average collided with A particles per second, so total number of collisions was N*A per second. If you multiplied the number of particles by 10 it would be 10N particles and each would collide with 10A particles per second, so total number of collisions goes up by a factor of 100. So, it’s a quadratic relation, not linear.
You are 100% right. My fault, didn’t read it all this.
In that case, considering the aircraft density of UK vs US, one should expect the MAC rate in the UK to be 21 times higher than the US. In reality it’s only 4. The UK is doing well, the US not so much. That’s the only conclusion. If we consider the UK to be OK, than the US is insanely high. It’s certainly not the other way around.
Most GA traffic in the US occurs in relatively few places, such as SoCal, Florida and the NY area. ADS-B really has been a game changer, it can actually be quite scary to see all the targets! Not sure if you can with a European sub, but zoom in on the LA area in ForeFlight and enable the traffic layer
This was a moment ago, and it’s a cloudy morning in Los Angeles.
Aircrafts don’t fly at random, so the model of random collisions is not a good model for aircraft collisions. Furthermore, most MACs are very much not in cruise, but in places where aircraft paths are even less random than in cruise, such as landing circuits.
ADS-B is the best thing to reduce collisions that has ever happened
Presumably this would be borne out by a statistically meaningful reduction in collisions? Has this been shown? The CAA correctly suggests that the technology will only provide timely target warning for less than 50% of collision risk targets. The usual suspects apply: no electronic conspicuity (less of an issue in USA as all aircraft radiate), masking of the signal (probably less in due course, when antenna diversity regulation kicks in), and not using Mark 1 eyeball lookout.
I tend to treat the information as not unhelpful, but with a heavy risk of placebo effect.
