The reason is that several civilian-owned lightweight propeller aircraft like those produced by Cessna have engines that are still designed to run on leaded gasoline and nothing else, because engine knock (mistimed fuel ignition in the cylinder, and the original reason for leaded gasoline) damages the engine and can cause it to fail mid-flight.
Most commercial and military aircraft used today run on jet fuel instead.
Which is the reason I assumed, but at the same time it doesn't answer the question of why those aircraft were exempted when we were able to ban leaded gas for every car.
there's also G100UL, an unleaded aviation fuel going through the certification procedures as a drop-in replacement of 100LL, the most common leaded fuel used in general aviation. ("LL" stands for low lead, and "UL" stands for unleaded. 100LL is already a major improvement compared to the avgas 100 those engines were built for.) like there are active efforts to eliminate lead use there too, it's just taking a while to do safely.
also, these aren't your private jets or something, these are small propeller aircraft people use for pilot training and recreation. they're an extremely important part of the food chain, but also nowhere large enough in volume to wreak havoc on the environment. banning lead for them would have been a massive blow to the health of general aviation as a whole for a minuscule environmental improvement.
Right, no, I already got that in vibes if not in facts and numbers, but...
Okay, full disclosure, my interest in this is rather personal and likely, I hope, very tinfoil hat thumbtacks and string theory-ish. My family is really big into aviation, have been since before WWII. Practically everyone on my dad's side either flies, or is immediately related to someone who does. That's also the side of the family that's the more conservative. Given that we've known for decades that any amount of lead exposure produces symptoms like increased aggression, decreased empathy, lowered cognitive function, etc. Which are also the hallmarks of conservatism to a degree...
Well, again, the tinfoil hat is currently firmly on my head, but it's frustrating to me that so many of my family's votes for someone who wants to strip my rights might have been influenced by something that is so ingrained in our lives simply because "it wasn't that important" to take care of and won't be until 2030.
I was in the "systemic lead poisoning is a conspiracy" boat, too.
Eventually, after taking some steps back, I've come to realize that a lot of what seems like conspiracy is really shortsighted decisions and a lot of kicking the can down the road for someone else to deal with.
Like, if there's one thing that legislators and upper management have in common, it's being too lazy to fix obvious problems because they aren't enough of a problem.
I may have worded that a bit too strongly, I don't think it's an actual conspiracy, but at the same time there seems to be a tantalizing correlation that makes it so damned frustrating to hear that something isn't "enough of a problem" to fix. Sorry a lot of this was just venting. I haven't had a terribly good week...
Again, short-sightedness and laziness. It's not enough of a problem for them if your family is lead-poisoned.
It's frustrating. The only way that they'll actually do anything is if enough people in the industry actually make it a big enough problem, which is what union strikes and class-action lawsuits are for.
Unfortunately, that requires that said people in the industry actually recognize that it's a problem.
i mean, on one hand, makes sense. but on the other hand, a lot of things in general aviation are just old because of a mindset of "if it ain't broke don't fix it" all the way from random mechanics to the head of the FAA. like people are straight up flying planes from the 50s and 60s and if you put a garmin in those you basically have an equivalent to a modern day cessna. there's literally more time between cessna 150 and present year than between the cessna 150 and the wright brothers.
you make a good point that the state of general aviation can be an influence towards regressive politics (unlike those planes, society is very much broken, and fixing it wouldn't cause a whole barrage of accidents until we figure out how to do things properly, like in aviation, but not everyone can make that distinction), and that lead exposure is dangerous and does make people stupid on its own right, but the reason i think aviation deserves the "necessary evil" treatment isn't because we have bigger fish to fry. it's because of other factors, like that it's a genuinely super difficult problem to fix it safely, or that the existing inventory of used aircraft props up the market to an anomalously high degree, which make strongarming aviation so much more difficult than something like cars which have much less rigorous safety requirements and significantly shorter vehicle lifespan.
that said, yes, leaded fuel in aviation is 100% a problem, and i'm not trying to argue against it being one. i'm just saying that it's much less of a problem than in other places where it was banned completely, and that strong policies against it would be much more harmful there than they have been in other places, specifically because of factors that are unique to aviation. but it still does need to be fixed, it's just not that big of an issue if we take a little longer to fix it the right way.
make no mistake, outlawing 100LL when G100UL is certified is absolutely going to cause damage. it's just going to be the acceptable kind of damage that doesn't result in lives lost to plane crashes, and while it will make things more expensive, it won't be prohibitive. once that line can be cleared, then yes, absolutely, go ham, and until then i think figuring out how to clear that line does deserve the maximum possible resource allocation. i'm not arguing against fixing the problem, or "just keeping it a little while longer because it's not that important", the point is just to not destroy general aviation in a process.
Because civilian propeller aircraft are not used in massive numbers like automobiles, therefore there is very little environmental push or financial incentive to convert the 80-year-old designs to new engines or retrofit new engines onto old planes.
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u/TransLunarTrekkie 1d ago
Friendly reminder that leaded gas is banned in the US EXCEPT, for some reason, in aviation use.
Use this information how you will.