The Drip, Drip Of Bad Publicity About 100LL


For the 40-odd years we’ve been trying to eliminate tetraethyl lead from avgas, general aviation has been a target of opportunity for dirty-little-secret headlines. The industry’s amazing persistence in preserving this problem has cost me at least several pairs of shoes trooping to press conferences where the various “stakeholders” offered progress reports we were all expected to believe revealed movement toward a solution. The latest of these is EAGLE, which now sets the goalpost at 2030, another at least seven years away.

Meanwhile, yet another poisoning-the-planet story appeared this week in Politico. It checks all the boxes, with most of the right sources and although it has some errors and assigns too much blame to ASTM’s sclerotic grind, it’s generally a fair story. It ignored how Santa Clara County withheld EPA findings about measured airborne lead levels around Reid-Hillview airport and that the Bay Area Air Quality agency stopped lead monitoring because levels were below EPA minimum standards. But a more recent study on blood lead level data showed that irrespective of airborne levels, BLL’s near Reid-Hillview were higher than might otherwise be expected. Read the full study here and decide for yourself. To me, this is compelling enough to merit further review.  

On the other hand, why? We’ve committed to eliminate TEL yet, at an industry level, we resist it kicking and scratching all the way. The safety argument and entreaties about the difficulty of transitioning are wearing thin. It’s a persistent bad look for the industry that only gives anti-airport forces a potent tool effective with an ill-informed public.

I really doubt that Reid-Hillview and other pressured airports in high-rent districts will survive until EAGLE’s aspirational goal of 2030. And California being California, there’s a statewide push to switch more rapidly to unleaded fuels than is realistic. It can’t be done in six months, but it shouldn’t take seven years, either.

You may have forgotten that what got General Aviation Modifications Inc. on the road to pushing G100UL across the finish line was George Braly’s belief that EPA’s lead health risk data would propel the agency to require its elimination before the industry had a ready replacement. That’s not the same as saying the health data represented a true risk, just that the EPA would use it as a cudgel. That’s in fact happening, but at a glacial pace. Many owners and pilots, rightly I think, are skeptical of the health risk claims so the ostensible argument to switch is that unleaded fuel is just better for engines. Eliminating TEL from the environment is a socially positive collateral.

I can’t prove this. No one can in anything like a long-term, large-scale study. Experience with unleaded autofuel is anecdotal and poorly documented and the Embry-Riddle durability test of G100UL in 2014 was only 150 hours. That’s not enough, in my view, to show large-scale benefits. I think it will take a year’s worth of highly controlled fleet trials over a lot of hours.

Promise was on the horizon when the University of North Dakota’s large training fleet was set to switch entirely to 94UL this year. This promised data from a large and consistently operated fleet that, in my view, would have yielded definitive answers on whether—or maybe if—unleaded fuels really do reduce maintenance costs to justify potentially higher costs, at least for 100-octane versions.

It didn’t happen. UND’s 100LL supplier made the school a price offer it couldn’t refuse and the school did what any of us would. It stuck with the status quo and is thus a beneficiary of oil companies doing what all companies do: Protecting a market with pricing power against a competitor that has less, if any, leverage. This sort of thing will continue to be a barrier to fielding unleaded fuel in both high and low octanes until the EPA finally publishes rules prohibiting TEL. And that will continue to complicate unleaded fuels gaining rapid market traction.

In the meantime, another thing will continue. The slow drip, drip, drip of news stories that paint aircraft owners as self-centered rich kids unconcerned about or unaccepting of their toxic emissions poisoning kids. While you and I may know this as not being true, if the defense of it is another four-letter FAA program that promises salvation in seven years on top of one that was already a $40 million failure, as an industry, we just look pathetic.  The best we can hope for at this point is for the FAA (and the alphabets and engine manufacturers) to get out of the way of GAMI trying to field G100UL through a whisper campaign that suggests it hasn’t been tested and we don’t know what’s in it. The FAA knows what’s in it. They oversaw its testing and so did Embry-Riddle.

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  1. It’s time for you to write an article for the larger mass media educating the masses about how pilots are … CPB’s 🙂

  2. Has there been a study on blood lead levels for pilots, mechanics, refuelers? The exposure level would be vastly higher (1000x+ I would think) for a pilot who flies piston engines every day than for someone in a house near the airfield. I would be genuinely curious of the results.


      Not only could it measure toxicity to RECENT exposure, but also for LONG TERM EXPOSURE.

      Many pilots–like myself–have been exposed to aviation fuels for a LONG time. Even better, many FBOs (again, like myself) have been exposed to it EVERY DAY FOR DECADES (55 continuous years in the business, ON AN AIRPORT.)

      This cohort of people exposed for many years means that we can get this study done QUICKLY–not a study that takes DECADES.

      Let’s study the workers and tenants at Reid-Hillview (as well as those across the country!) –we should be able to prove/disprove this theory of “lead poisoning” once and for all–quickly–and at low cost.

      • I agree that this would be a good study topic. Hopefully someone will fund it and develop a sound process.

        As I understand it, lead levels in blood typically show short-term exposure. For adults, most of the lead in blood is gone after two weeks. But for children the lead remains in the blood for a lot longer. And in adults, lead can be ‘stored’ in the bones for 20-30 years, only to return later.

        Because children’s bodies store lead differently and, by definition, are growing, the effects of lead poisoning are more pronounced.

        So a study of lead levels in blood alone may not tell us enough. A study of lead-poisoning in airport denizens may need to look at other tests. But I don’t know enough to know. Hopefully some one with appropriate credentials can chime in.

        • I’ll volunteer for that study, started my logbook at 9 years old, worked side by side with dad on our family airplanes, flown my whole life, ready to retire from the airline and flying piston airplanes more and more… I’m probably a good candidate to check against a city kid with no drivers license to compare the lead differential.

  3. It’s time we move forward and eliminate TEL. Then we’ll figure it out from there. Some regions like Alaska have been using Auto Fuel forever because many communities do not have anything but a boat fuel stations. ⛽

    So many certified aircraft are over 50 years old. It’s time for change and if changing the fuel pushes the industry forward, let’s do it. 🛫

  4. Paul is right and no amount of studies or rationalization will change the trajectory of what’s happening here. We pilots and operators believe we have a right to fly, but the public does not agree with that idea here in the US or anywhere else.

    Most of the public are afraid of “little airplanes” and dislike the noise. They get actively angry when someone mentions lead and carbon. There are no rational excuses for aerosolizing lead into neighborhoods (or anywhere else), only lame excuses (it isn’t as bad as something worse).

    Let us also not forget the unpopularity of carbon emissions. Airlines are increasingly public about their CO2 emissions and there are no defenders of GA, whether piston or turbines.

    The only way that GA’s future can be positive is if the industry wholeheartedly moves into a “public good” model. No more lead in fuel. Noise abatement. Multiple uses at airports. Sustainable fuel, preferably electric (yes, electric). Real public engagement.

    The airports here in LA are rapidly shutting down. Santa Monica is in hospice. Whiteman and Van Nuys are both under attack from their owners (County and City of Los Angeles). Similar stories are happening in all cities everywhere, including NorCal. The story is significantly worse in other parts of the world where the concept of general aviation is universally regarded as inequitable and unsustainable.

    While aviation folks may react with some political point of view, the fact is that defenders of GA are outnumbered by many orders of magnitude by those afraid, concerned, envious, or oblivious. The Politico piece is a shot across the bow. Time to wake up.

    • We are not alone. The Marxist inspired hate of other people’s interests is EVERYWHERE. (This has nothing to do with communism and everything to do with the overall collection of ancient dirt Marx threw together in his writings).

      Wouldn’t it be nice next time someone on stage or online made a snarky comment about how “No one needs a _____”, if the reaction from every pilot, fisherman, hunter, musician, motor cyclist, snow boarder, golfer, oenophile, car lover, SUV owner, camper, surfer, etc. was to object and leave?

      I think it would. And I think it would lead to some seriously good changes.

      • This comment, which is one of your many such comments, both a) misses the point and b) underlines why most people, regardless of politics, are unsympathetic. You want the right to trample, yet others desire not to be trampled.

  5. The fight is over and GA lost. The merits of the argument don’t matter anymore, it is imperative that we all get ahead of this.

    Everyone has to come together with a plan to transition to unleaded Avgas on a realistic timeline. Otherwise we seed the initiative to the anti GA folks who will force airport closures and and early chaotic outright ban on leaded Avgas.

    • I’ll forego the all caps, but I almost screamed out at your remark, “It will not stop because we change fuels!”

      • Yes, GA is always vulnerable to the “rich guys toys” argument, but fighting to keep leaded fuel is foolish.

        It is one issue that is easy to message to the average non aviation person; “GA is poisoning children ! “ and can be leveraged in multiple ways that will disadvantage GA.

        We have to get in front of this issue by proactively moving to unleaded fuels.

        • No, if you cave, they just come after you harder. What needs to be done is to fight for good terms. Take EVERYTHING the FAA and other government institutions have done that hurt GA and ram it down their throats while blaming THEM for the lead in our fuel.

          Job one is getting the FAA almost completely out of the certification business for GA. The issue isn’t the fuel, it’s the engines. We need new engines. It’s tort. We need new planes to not carry 100k each in embedded insurance overhead. It’s deleting every useful airport and thus destroying economy of scale.

          We know living next to a freeway is terrible for kids, but we still have freeways.

          You’d think with all their money AOPA would be heard from except for advertisements directed at pilots. Nope. They refuse to risk burning bridges by shaming the FAA.

    • It is not us pilots that are resisting and thwarting progress on unleaded fuel. Essentially any and all of us would switch to an appropriate UL avgas if it were available. It might be the various alphabet organizations who are trying to hold things up but it is not us so quit blaming us!

  6. Here’s a scary theory: For decades our entire population was exposed to copious amounts (as compared to aviation’s miniscule contribution) of lead from motor fuels dispensed by every service station. Lead, they say, causes mental problems. Today we are exposed to the thinking of our fellow humans as never before, and what conclusions must we draw from that?

    I rest my case.

    • You may not be far off. There is a strong correlation between leaded gasoline usage and crime. As leaded gasoline increased, there’s a corresponding increase in crime 20 years later. And as leaded gasoline was phased out, there was a similar drop in crime about 20 years later. The theory is the two-decade lag was due to children exposed to lead growing up to become criminals.

      You can read more details here:–crime_hypothesis

      • There’s a lot wrong with that though. First, there are other correlations. Second, the amounts of toxicity really matter a lot.

        There’s arsenic in your tap water.

    • 27 hours of piston engine flight training dump 1 pound of lead into the environment. Do the math. The cumulative effect is any one’s guess. Salt is an essential nutrient, yet the Dead Sea is called dead for a reason.

  7. Surprised that the current regime in office hasn’t just banned import of lead or lead based products into the country by executive action. That has been done in the past with certain kinds of firearms. With no 100LL, no flight school would be able to operate which could create a real “pilot shortage” for the airlines, until a substitute is distributed.

    • The Obama EPA shut down all lead mining in the US, and now if you can get it in any form -batteries, bullets, weights etc, it is totally from recycled sources and that is why Pb containing anything is 5 or 10 times more expensive than it used to be. Biden’s EPA could do the same with TEL just like they are now doing with gas stove appliances. Do not kid yourselves.

    • Flight schools and the 1500 hour stupidity rule are the main reason for animosity toward the aviation community. Hundreds of “students” paying thousands of dollars for what? to repeatedly fly over neighborhoods in ascending and descending circles over and over and over again in 50 year old aircraft? If Republic, FedEx, UPS, American, Delta and Southwest need pilots they have the resources and expertise to train them. Don’t be surprised when freight planes are piloted remotely by kids living in their parent’s basements.

  8. Honestly I have doubts about Quality Control with these small batch new blends that use disparate base materials. If nothing else 100LL is a known stable commodity and I like that when it comes to safety.

    • And yet it’s likely that many, many low-compression airplanes could run on 93 octane E10 without modification. In fact, it’s done every day. I’ve seen people put pump gas in their Cessnas.

      • We need more numbers, not more division. It will be too late for you to see the foolishness of your scheme when the high performance planes are gone and the next shoe drops. I was in Europe at what was probably the low point of their piston GA hell, it was not pretty. Not at all.

      • Any fuel with ethanol in it is prohibited by both Cessna engine manufacturers.
        Also, ethanol is highly corrosive to aluminum, as in the fuel tanks, fuel lines, fuel selector.
        So, it’s a very bad idea to use any amount of ethanol in the fuel system.
        Then there is the vapor pressure problem if flying at higher altitudes.
        Cars can tolerate ethanol since the fuel tanks are steel as are the fuel lines…

  9. In Washington State, some legislative representatives have, of course, included eliminating “leaded aviation fuels” in a bill (Washington House Bill HB 1554) which was in committee discussion last week. This bill contained mandates such things as forcing airports to sell only “unleaded fuels” (relatively immediately), relocating run up areas to be distant from any nearby housing and, believe it or not, legislating limits on the length of time any aircraft engine can be run up on the ground.

    Of course, there was no harmonization with any national efforts or plans.

    Needless to say various local pilot groups are up in arms at this lunacy/ignorance with a lot of people submitting comments to the legislative committee involved and also subsequently emails to individual committee members urging them to vote the bill down. Of course, the committee has now revised the bill (some concessions) and watered it down a bit. However, it still is written without any reference to national programs/timescales that industry groups have been working with the FAA. The revision also pushes a lot of work onto airport owners/operators to now work with lead monitoring agencies and create plans that need to be implemented within 1 to 2 years to mitigate and monitor lead issues.

    To be clear, the original and revised bill ignores the general lack of supply for unleaded aviation fuel, the authority of the FAA over the operation of aircraft/airports, aircraft/engine certification/approval processes for fuels, the fact that aircraft routinely cross state borders so they would be “tanking” leaded fuel back into the state just through normal operations, the simple safety of flight issue that comes from having a pilot worried about a potential fine should he/she run up for too long instead of worrying about the aircraft/engine performance during run up, the cost of extra airport staff to enforce the bill’s airport requirements, etc. The bill is truly epic in its departure from any reasonableness.

    We all want to eliminate lead from our lives, and in our aviation fuel, but to do so in ways that sacrifice safety, process and which also potentially cost owners, pilots and airports more money, is nothing short of ridiculous. (Yes, the bill still proposes a $10K fine for violation of any of its points that are not “fixed” within 30 days of notification of the problem – either levied against airport owners/operators/staff and/or aircraft owners/operators/pilots).

    There are so many people we collectively need to educate to avoid this type lunacy springing up in a patchwork of “concerned” State Legislatures …

    • Collectively educating liberal democrats in blue states, would be like teaching a bowling ball how to swim. They don’t care, and won’t listen to reason. They would shut down all GA airports if they could.

      • And educating conservatives in red states is any less challenging? I’m sure they’re concerned about lead pollution too even if us pilots see it as less of a danger than the media makes it out to be.

        • At least there are still some small government conservatives who would realize we weren’t lying when we pointed out the realities. Also, they would likely be suspicious of the idea of forcing all the costs and work onto the airports.

          Personally, I’d be looking into who is funding the push, and what their agenda is. Likely it’s either lead testing companies, lawyers, or someone with a particular airport they want to close so they can get hold of the land.

  10. With cars, the argument was that lead, either in the pump or from bottles was necessary for older cars with soft valves, which would not run on unleaded.
    Guess what — 20 years down the line, many, if not all, of these engines have been taken apart and harder valves, and if necessary, valve seats, have been installed, so they run on unleaded.
    The price of hardening a set of valves is not very high, €150, but the kicker is in the labour to take the motor apart. Even so most owners have made the change, for convenience
    and above all for resale value.
    I am sure a similar scenario would play out with aircraft, but only if unleaded fuel was made the norm, as it is with car fuel.

    • The argument that lead “cushioned” or “lubricated” the valves turned out under analysis to be incorrect. The theory came about because there was anecdotal evidence of an increase in valve-seat recession problems when leaded gasoline was phased out. The grass-roots theory was that lead somehow deposited on the valves and valve seat to prevent this.

      The reality is the problem was actually due to pinging due to low (but legal) octane levels. Leaded gasoline often had a higher octane that what was listed on the pump. Lead was cheap, it was easy to add a little extra to insure the gasoline met or exceeded the rated octane. When lead was banned it was now much harder to meet that value.

      As a result, the 87-octane gasoline coming out of the pump was now exactly 87.0 octane instead of being 88 or 89 octane. Cars that would normally run just fine on “87” octane (that was really higher) would now ping running on the ‘same’ gasoline. The light pinging over time would cause valve seat recession.

      With airplane engines, the problem is much more pronounced. Low octane gasoline in an engine designed for 100 octane can quickly self destruct from “knocking” or detonation, regardless of where there is lead in it or not.

      GAMI’s 100 octane unleaded fuel (“G100UL”) provides the high octane without lead, and without needing to modify any existing engines.

  11. Perhaps the whole issue is the engine, not the fuel. A lower compression, high rpm, automotive type engine with a reduction gear for propeller speeds may be the answer. Horsepower is a function of basically 2 factors – rotating mass and rotational speed.

    Our high compression lumbering dinosaurs using 1940’s technology should be scrapped. As engines reach TBO they can be slowly replaced with modern engines. Honda makes a 2.2 liter racing engine that revs to 12,000 rpm and produces 550-700 horsepower in a 250 pound package. Obviously there are less extreme alternatives.

    Reliability of automotive engines today is definitely ‘aircraft quality’. The only downside would be that our aircraft technicians are not ‘automotive quality’.

    • “Reliability of automotive engines today is definitely ‘aircraft quality’.”

      The statistics of the experimental segment does not bear out the statement that automotive engines are “aircraft quality”. The engine failure rate is significantly higher with automotive conversions than with traditional aircraft engines.

      • Amateur conversions cannot be compared with professionally engineered products. Automotive engines are reliable. To convert them for aircraft use the sensors, spark plugs, and computers all need to be duplicated. They are set up with airflow and density sensors so the computer adjusts for altitude. They would be single lever engines. Many have direct injection which prevents detonation with lower grade fuels. Reduction gears absorb propeller thrust so massive engine bearings are not needed. Most are water cooled so the cabin heater can be isolated from the exhaust system eliminating the carbon monoxide danger. There is little downside save stubborn grey beards.

        • What ended up happening to Mooney and their M20 that had a Porsche engine in it? Not many were built. It did not sell and most were converted back to aviation engines.

      • But in the main the automotive engines being used are 1940’s designed Corvair / VW type blocks – not MODERN automotive engines. You need to reformulate your numbers based on true MODERN block conversions and see where that gets you.

    • Yep, the engines need to change first. Attempts at diesels create balance issues in the existing fleet, but not in new designs.

      At any rate, there needs to be an end to selling new planes that require leaded fuel. When there’s money in it, and the FAA has a deadline, we will get new airplane models. The price will come down as volume goes up.

    • Every so often on one of these threads I add this same comment to remind everyone of the facts. Most airplane engines – especially those “old” ones from the 1940’s and 1950’s – were designed to run on lower octane fuels and have never needed 100LL. My Skyhawk runs on 91 octane unleaded Avgas just fine – and so does every other stock Skyhawk, C150, Piper Cub, whatever you want. We only burn polluting oil-fouling 100LL because it’s the only thing they sell at the FBO. Statistically, the vast majority of airplanes in the fleet would NOT be grounded by an instant ban on 100LL tomorrow. There is no requirement for some sort of massive fleet-wide re-engine program. Flight schools would not suddenly stop. The world would keep turning. Some POHs would need updated, and some stickers issued, but that’s all.

      But – and it is a big “but” – there are also engines and aircraft out there that DO need 100LL. These range from high-performance Cirrus types through to big old twins, and they can’t get by on 91 or 94 octane fuel. Since I can run on anything from 91/94 to 100 octane (even though I don’t like the lead) but they need 100LL – that’s why the FBO sells 100LL.

      The simplest way for an airport to reduce the lead footprint in the vicinity would be to add a second pump for unleaded Avgas, and all the smaller engines would immediately switch. It’s better for the engine, better for the wallet, better for the environment. You might think it is a no-brainer.

      Unfortunately I am also aware of the ironic reason why they don’t. The environmental paperwork and rules to put in a fuel facility are so onerous that an FBO is very unlikely to go through it all a second time for a second fuel stream which is simply going to split the fuel flow without actually generating any more revenue.

      Oh well…

      • Great point. The objective is to reduce the lead footprint. The EPA and the FAA are clueless.

  12. I wonder if there have been any studies of lead toxicity around gun ranges – which have large air extract systems to protect the users from lead dust from bullet impacts?

    I wonder how many gun ranges are situated near airports?

    • I will postulate that me consuming 10,000 milligrams of lead chunks and powder would have less effect than a like amount of tetraethyl lead.
      I’ve been a circuit builder for more than half a century, and I don’t use lead-free solder. I’m also a reloader, and used to shoot many thousands of rounds per year. I had one lead test done, it was within range. Haven’t had one since, no need.

    • There have been on some clay pigeon ranges and some long established ones were so contaminated in the area where shot came down they were shut down.
      Some were able to lift the top layer and sift out the pellets, others not.
      That I why most clay pigeon ranges now insist on steel shot.

    • If I remember correctly there have been studies related to lead shot in water affecting wildlife reproduction. Lead persists in the environment for a long time. Lead bullets with lead oxide patina are still being uncovered 150 years after the Civil War.

  13. We don’t need unleaded avgas on any real, genuine health grounds. The lead measurable in the atmosphere is as is correctly put, so small as to be a non-issue even near the most heavily used airports. Globally most GA airports have so few movements that the lead levels would be below detection limits of any of the available test methods. I’ve been in the aviation fuels and GA aircraft commercial operation and ownership circus for around 40 years professionally and am qualified (highly) as a chemist in the aviation fuels and lubricants business, a commercial pilot with a hell of a lot of experience, and have an enormous number of air-cooled engine overhauls under my belt. There are currently NO AVAILABLE UNLEADED FUELS GLOBALLY that I’d even consider running at all in any aircraft engine I have owned. They are just NOT necessary, and are in fact harmful to some in certain operational circumstances in certain engine types/installations combinations. There are IMO, a hell of a lot of people globally with a hell of a lot of self-congratulation going on, but who are still so far from properly understanding the FULL impact of all of the current offerings on a significant proportion of the fleet, that it’s extremely important that programs like the ‘wound-up’ PAFI and the new EAGLE program are allowed to INDEPENDENTLY cover all of the issues without any personal interests involved. I could go on for many hours about some really serious operational issues of using any of the existing (and defunct) unleaded avgas offerings, but that’s not going to happen in any public forum… The delays have been IMO absolutely justified and should continue until all of the relevant issues have been PROPERLY and throughly discussed and addressed. Enjoy the process everybody, and ignore the noise being created by a lot of people in industry and government and dare I say ‘fools in various interest groups’ who are stirring up hysteria about us all being biologically affected by tiny lead pollution after the worlds population sat in traffic for decades breathing lead filled fumes every day of their life, yet still had the brains to go to the moon, make iphones and PC’s and actually live long healthy lives….. it’s such a joke that people think the tiny bit of lead left in the atmosphere is a problem to anybody, whilst ignoring the real issued with the alternative fuels…..

    • The entire world, minus a very small percentage, disagrees with you. Now what do you recommend?

  14. Show me the long term study directly pointing at leaded aviation fuel as the source of children harmed by inhaling byproducts from leaded aviation fuel. We have multiple decades of leaded fuels in use on highways and skyways so, assuming there is direct evidence, it should be easy to demonstrate cause-and-effect, not anecdotal correlations.

    Show me the proof that removing leaded fuels in an environment reduced the “harm” said to be caused by leaded fuels, not just in the aircraft engine but, in the human population, as well. We know a few studies have been done to attempt to force unleaded fuels down GA’s throat (and a few jurisdictions passed ordinances with the same goal) but, where is the evidence this will do anything besides stoke someone’s equity numbers to their peers/community?

    Would it be nice to remove lead from fuels? Sure. But, the cost is prohibitive for the GA fleet to convert the old engines over. Someone is going to make a lot of money doing this – and it’s not the GA fleet owners.

    Likewise, passing ordinances to prohibit leaded fuels with no substitutes is a fantastic way to shut down some prime real estate and redevelop it as fantasticly expensive homes/communities. After all, the airport was there first but, the wealthy neighbors – who’ve been trying to get it shut down for years/decades – just found a new “hammer” with which to achieve their goals (all while looking wonderfully ESG to their peers).

    If you want to see a transfer of wealth, just follow the laws portrayed as “saving the planet”. They rarely save the planet but, they do destroy jobs, careers, lives. Understand why the folks demanding the elimination of a product with nothing but anecdotal evidence push so hard. Once you find the source of their agenda, you’ll begin to understand why they’re so adamant. And it won’t be the reason they’ve been so vocal about.

    • As others have pointed out, there is a correlation between lead and crime. Correlation != causation, of course.
      But tetraethyl lead is nasty stuff; it should simply go away.

  15. So many of you are saying that GA should get a free pass on this while others had to deal with it, and did so.

    If GA gets a “hall pass” why shouldn’t other groups get one too.

    Maybe we could find a viable solution. Something like, no new GA aircraft built from this day forward will be powered by an engine that requires leaded fuel. And all overhauls of engines that require leaded fuel will either not be allowed or will be a conversion to use unleaded fuel.

  16. There is no question that lead is bad for people arguing about levels is nonsensical.
    Just because something has been done for a long time does not make it smart or right.
    We have learned that a lot of things that used to be done were bad for us; we stopped doing them and are better for it.
    People “Believe” lead is OK; “Believe” is not fact or reality; we know better.

    As for lead in engines; In Canada, my friends from refineries have confirmed that 80/87 never had lead in it here; lead was allowed if needed to achieve octane levels, but was never needed.
    It is likely that 80.87 in the US was also lead free; the lead was not needed.
    When 100LL was introduced, we started having problems with engines that never had problems before.
    Valves and sludging of oil passages, particularly in small Continentals or old low compression engines of any kind.
    A mechannic friend just showed me pictures of an engine which failed due to lead clogged oil passages in the crankshaft; an expensive forced landing.
    An engine that was approved and should have been operated on unleaded fuel; Mogas.

    Lead is not good for valves; all aircraft have hardened valve seats; so any issues of valve recession, simply don’t happen in aircraft engines.
    Cylinders on approved engines go much longer without problems on Mogas; at least 50 percent more life; that is fact.
    Unleaded fuel is better for engines.

    Taking forever to introduce unleaded fuel is nonsensical.
    Unleaded 100 has been in use in Scandanavia for years; engines and people are doing fine.
    Lead for fuel is only produced by one company; the only ship that transports it is very old; it could go out of service at any time and would not be replaced, because lead contaminates whatever it is transported in.
    The supply of lead for fuel could be gone at any time; get in front of the problem!
    Stop fighting the inevitable; get things moving; we will all be better off.

    • “Unleaded 100 has been in use in Scandanavia for years; engines and people are doing fine.”

      I believe Europe uses a different method of calculating octane level; 100 octane there is closer to 96 octane here, as I recall.

      I’m not sure if Scandinavia uses the same european method or not, but even if it really is 100 US octane, there are other factors that are involved with aviation fuel. Just a couple I recall is the longer required stable shelf life and the variation in vapor pressure due to altitude and temperature extremes that auto fuel doesn’t have to be concerned with.

    • If you really believe level’s don’t matter, stop eating and drinking altogether. Also, exempt yourself from any discussion involving science. If there was ever any real consensus in science it is undoubtedly that levels matter.

      Please feel free to back pedal or retract your statement.

  17. Hjelmco Oil in Sweden introduced unleaded AVGAS as per standard D910 already year 1981. Our second generation unleaded AVGAS Hjelmco 91/96UL was introduced year 1991 and approved the same year by the Swedish Civil Aviation Authority. Lycoming approved the fuel already year 1995 in their SI 1070. The 91/96 UL AVGAS met the D910 standard for grade 91/98 leaded AVGAS. The 91/96UL AVGAS is the standard AVGAS in Sweden and we have millions of flight hours on thousands of aircraft and under actually any weather conditions for 3+ decades. So sure there are data. The reason for it is so much used is also that is about one dollar cheaper per US gallon than the 100 LL.
    There is a reason why the US have their problems and that is that Flight Magazines etc have avoided to tell the market that there were solutions outside the US. For example the AOPA Pilot has never written anything about the Swedish unleaded fuels except for a two inch long article when our unleaded AVGAS 91/96UL was tested and observed by AOPA staff at GAMI on a Piper Navajo Lycoming TIO540 engine with everything in the red and still not knocking. (with the help of GAMI Prism system). So journalists are also responsible for the US situation.
    As I have developed both the first, second and third generation of unleaded AVGAS I have made several attempts to gain acceptance in the US. Town hall meetings have been made in California 11 years ago!!. I refer to flying Magazine You will the Power Point presentations if you Google.
    So what about the future? Exotic new fuels will be expensive – you will have to pay for the octane numbers. Just compare the difference in price for high and low octane car gasoline at the pump and then extrapolate to gain another 10 octane numbers with exponential increase. (octane numbers get exponentially more expensive the higher you go) There will be I predict changes to the engines to operate on mid octane unleaded AVGAS. That should be the most cost effective solution for the GA and will be on a path with no technical surprises.

  18. I just read Paul’s article, the Politico article, and the 2023 article “Leaded aviation gasoline exposure risk and child blood lead levels” (by Zahran, Keyes, and Lanphear) published in the Proceedings of the National Academy of Sciences Nexus (a peer-reviewed scientific journal published by the US National Academy of Sciences, one of the most respected scientific agencies in the world).

    The Zahran et al. article makes a compelling scientific case for an association between blood lead levels among young children and (i) airport proximity, (ii) prevailing wind direction, (iii) volume of piston-powered air traffic, and (iv) sales of 100LL (all at Reid-Hillview Airport in Santa Clara County, California). I see no way to examine the results and not conclude that 100LL was a meaningful contributor to blood lead levels among the children in the study.

    Making matters worse is the fact (which has been known for a very long time) that lead is bad for humans with the greatest adverse effect on the neurological development of young children. Arguing about a possible “safe” level of lead among children isn’t useful because determining such a level is probably not feasible. Given current knowledge, experts worldwide strongly recommend efforts to reduce lead in the blood of children to levels undetectable with standard clinical tests. The epidemiological and toxicological basis for this recommendation is very well established in a large, credible, peer-reviewed scientific literature.

    If 100LL is the single largest source of lead emissions into the environment in the US at the current time (as noted by multiple credible sources) then general aviation has problem and it isn’t going to go away until the lead is removed from avgas.

    Imagine two water fountains next to each other. Above one is a sign that says “the water in this fountain contains measurable amounts of arsenic but at levels not proven to poison you” and above the other is a sign that says “the water in this fountain is just like the water in the other fountain but has no measurable arsenic in it.” Which fountain do you think the general public would want to drink from? Which one would you drink from?

    BTW, I fly and maintain an experimental homebuilt airplane, I own, maintain, and drive/ride an antique car and an antique motorcycle, and I have fired tens of thousands of rounds of ammunition in indoor and outdoor firing ranges. I am not interested in limiting anybody’s fun or livelihood. I am interested in facts, and the facts about the effects of lead on human health are pretty clear and seriously unfavorable.

    • Well, since the most believable scientific paper issued ever concluded that 95% of peer reviewed scientific papers are basically wrong, you could try reading more skeptically. There’s undoubtedly a way to read those articles and keep an open mind.

      There’s something about this subject that gets everyone to try to steal bases in their arguments. It’s not necessary. There is no pro lead camp. No one actually wants the lead. The resistance is generated by the hyperbole along with lack of proposals that don’t include taking care of the real victims which are the aircraft owners. There are much bigger environmental concerns which should be a priority, but aren’t because they have more politically powerful people to fight.

      If the government, which is very much responsible for this situation, wants to pay for a fix, let’s hear about it. Until then, let’s please stop trying to take science out of the discussion as settled. It’s not settled, and the fiction is an even bigger problem than all the lead in all the planes will ever be.

      • The science is never settled, and scientific research has become so biased it simply cannot be trusted as absolute, or definitive. The relative toxicity of ANYTHING is based upon degree of exposure not the contention that any exposure is bad. The established science of toxicology is based upon rate and duration of exposure to anything. At some rate or exposure, everything is toxic, and at some rate or exposure nothing is toxic, including lead, arsenic, mercury, dioxin etc.

      • Seriously, 95% of peer reviewed papers are wrong? 27 hours of piston engine flight dumps 1 pound of lead into the environment, do the math. I have to agree with Dale, salt is a essential nutrient, why is the Dead Sea called dead? Aircraft owners are the victims of what? lack of creativity, lack of technological innovation. They can’t afford mufflers.

  19. I already told our airport commission that as soon as 100UL is available anywhere within 50nm, I will be going there for fuel, so if they want my business, they should try to be an early adopter. I want the improvements to my engine longevity. Regarding the environmental and health impact, I don’t think it’s worth arguing over. It’s a negative pollutant, not a positive, so we should do what we can to get rid of it. We should in all cases, try to have as minimal negative affect on the earth as is practical. Personally I’m sick of having all my food contaminated with glyphosate and phthalates, and would love to see them gone as well.

    The biggest problem I see, with moving the fleet to 100UL, is that we’re gonna need someone to develop a cologne that smells like 100LL being burned. For some reason I just love that smell, and I’ll miss it when its gone. 🙂

    • A little dab of WD40 behind the ear. Might not smell like 100LL, but you do get the shop ambiance.

      To this day, burning JP8 smells like breakfast.

    • All my food contaminated with glyphosate or phthalates… pure nonsense, if you believe this than you have absolutely no credibility or data to support such tripe.

  20. I use Santa Monica airport and I’m not happy.

    As a community, we have had our heads in the sand about lead – and for decades we have had our heads in the sand about noise.

    I suspect most airport neighbors’ opposition isn’t really motivated by lead: it’s motivated by noise. And for fifty years and counting we’ve said “we shouldn’t have to be quiet – we were here first” and we were being stupid. It’s possible to be quieter: listen the next time a Rotax-powered training airplane takes off and compare that to a C152. Higher RPM, 3-bladed prop, effective muffler, world of difference. Then listen when some numbknuckle does a full throttle departure in a large-engined piston with the prop all the way forward and the tips going at M1.05, when it’s been shown that a lower RPM – with dramatically less noise – would give better takeoff performance. It’s as if we were actively trying to make enemies.

    Yes, we were there first. So were the cars. Know what? The cars got quieter: we didn’t.

    And the same goes for lead. Those noisy C152s were originally designed – 50 years ago, or more – for unleaded fuel. They’re still getting lead fouling from the garbage we have in our airport fuel tanks. It’s not like there’s any mystery about how to make engines run on UL94: drop the compression and accept that you get less hp per cubic inch. And if that’s too heavy, join the 20th century (it’s quarter way through the 21st), put a gearbox on it and increase the RPM – yes, it’s entirely feasible and the fears about gearboxes are unjustified, resulting mostly from the efforts of amateurs trying to put gearboxes on automotive engines for Experimentals. Geared engines are quieter, too. But, for 50 years, we refused to adopt any new engines (except the Rotaxes – and then painfully slowly). And we have refused to tell the operators of planes with antique engines that it’s time to derate and run on 94UL.

    Soon we will have no more urban airports, and we’ll be able to sit in our recliners with photos of our old lyco powered chariots on the wall and grumble that we were there first.

    • The noise is obvious and an irritating annoyance. The lead pollution is basically unknown to most people who assume it was eliminated years ago. Combine the noise with the unknown effects of the lead pollution and animosity grows. Add the increased traffic caused by the 1500 hour stupidity rule. The choice is evident, The Flintstones or the Jetsons.

  21. As a child raised in Los Angeles with parking lots for freeways and cars running on leaded fuel without converters, I cant see how a few planes a day is contaminating kids???? I know that a lot of planes that can are running on auto fuel to save money. I’m sure that is the same at most all airports where people have the ability to purchase non-alcohol fuel (not Arizona).
    Question is how did my generation survive? There should NOT be any baby boomers if this is where the lead in the children is coming from.

    • Low level lead exposure doesn’t kill directly, a few points knocked of the ole IQ, decreasing executive function and making self preservation a little more challenging. Maybe we should be adding lead to the blood testing done post accident. Any running out of fuel and vfr into IMC- test that pilot for lead exposure!

  22. The talk about lead harming the engine is not addressing the problem that was caused when it was decided that they would only produce one fuel for aviation. Anyone remember RED, BLUE, GREEN, and PURPLE fuel???? 100LL was a compromise fuel that was added to the mix.It contains more lead than the old 100 Octane but less than the 115. Yes low compression engines don’t like it or need it. But high compression engines NEED it. Go to the Reno race and see what they are using, its not 100LL (VP racing fuel LEADED) say goodby to motorsport racing if you cant have leaded 130 octane.

    • Two things: we don’t NEED those high-compression engines; and what we in aviation call “high compression” engines don’t really NEED 100 octane.

      What do I mean?

      If you “de-compressed” those engines from 8.5 to 7.5 (which would require a different cylinder head but gets done for turbocharged variants already) they’d lose about 4% of their rated power. You read that right. Yes, it matters, but it’s roughly the effect of 1,000’ of density altitude.

      And, our “high compression” engines have ratios of about 8.5:1. Automotive engines burning lower-octane auto gas are running at ratios of 8-12. They use techniques like shaped cylinder heads, fuel injection and modern ignitions, but it’s all entirely feasible. One of the things that make it possible: the lack of lead deposits inside the cylinders.

      Meanwhile we collectively incur many millions in annual maintenance costs and lose a few lives to engine failures caused by lead jamming the valves.

      The idea that we have a fleet of engines that “need” 100 octane is at once technically true, borderline myth, and a disgrace.

      • Most twin engine airplanes cannot afford a reduction in power due to their marginal single engine performance they were certified to. Single engine planes would lose weight carrying due to go around performance those planes were certified to. Reducing power in planes already certified at their original levels would just open up another can of worms and would ground most of them.

  23. I have done some research on the cause of death in the United States in 2020 and found some big numbers. Hiway deaths at 32,719 and 2.3 million injured. Work place deaths 3929. Heart attack and cardiac 600,213 . Tobacco related 159,260. Other cancer related 585,202 and drowning & injury at 785 with 79% of these victims under 5 years old . No where was any mention of death and injury from avgas which only comprises 0.19% of the total gasoline sold in the US.. Looks like Avgas is not much of a threat to mankind so issue cooked up about it being a dangerous commodity is really a non issue. George Gould @ KGLS

  24. How far back in the archives did you have to search to find a photo of a plane being refueled with 100LL for only $2.49 a gallon?

  25. For those reading this far, a couple notes from the ground on the famous RHV Lead Study:
    1. Econ Professor Zahran never measured anything.. He simply took state blood test data and did a series of correlations of his assumptions around activity, sources and surroundings
    2. His study used the upwind corner of airport property as the “center” of presumed lead dispersal because it was closer to more homes, rather than the downwind corner near Run-up area, which is surrounded by commercial and industrial sites.
    3. He assumed lead plumbing in the old school buildings adjacent to the airport was not a factor at all, and also assumed lead paint in the older homes around the airport was a non-factor (as he was told to do..) even though the county collected $100+ Million from paint manufacturers in litigation for lead contamination from paint in those very homes.
    4. And finally, he ignored higher blood levels in several other zip codes not near the airport, including downtown San Francisco where clearly older homes with lead paint and lead solder in plumbing are the cause of the elevated blood levels…

  26. Soooooooooo many people here simply have NOT A CLUE about this topic. It’s NOT THE LEAD that is the issue with taking lead out of avgas. The key problem is to look outside your own back yards, or Scandinavia, or Canada, or the mid-west or, or in Narnia or whatever, and for just one minute look at this issue as the GLOBAL ISSUE for God’s sake – which is exactly what it damn well is!

    There are many engines in working (i.e. commercial operation) aircraft, that are unlike your low HP experimental aircraft or your ‘weekend worrier’ little single engine toys etc that in their operational environments which are all very different to you meandering around your moderate weather holiday homes etc, that simply cannot operate safely and reliably long term on this ‘greenie’ unleaded avgas. The CURRENT alternatives to leaded avgas which are chock full of high levels of aromatic hydrocarbons that are necessary to achieve the required octane ratings for some higher HP engines are a problem…. a big problem!

    We can’t have multiple different avgas types (formulations) at every airport in the world, and again…… STOP thinking about your local huge GA fields in suburban USA and start thinking about Africa, remote areas of Asia, outback Australia, and dozens of other places where there is a huge amount of vital commercial operation in very harsh climates where the wrong fuel compositions cause SIGNIFICANT ENGINE DAMAGE. This is already happening as fuel companies bow to pressure and keep reducing lead levels in 100LL and increase the aromatic hydrocarbon levels to maintain the fuel to the octane requirements of ASTM D910. Why the engine damage you ask? Well go get yourself a degree in material science and combustion engineering and you just might begin to understand. Have a look at the combustion temperature issues with these high percent aromatic hydrocarbon (lead free) fuels and consider how they affect engines OTHER THAN YOUR OWN under-stressed toys. Geez, talk about couch ‘experts about everything’ (the typical private pilot) not having the slightest clue about the bigger picture!!!

    • Technically, some of those big engines need 100 octane. But from an engineering point of view, that could easily be fixed with a very modest loss of performance – and a significant reduction in maintenance costs would result.

      As for not having a clue about the bigger picture…

    • Not really concerned about damage to an antique mechanical engine. More concerned about the damage to tree frogs, turtles, salamanders, crayfish, possums, raccoons, deer, birds, bees, etc. How does the noise pollution, air pollution, and exhaust particulate effect them?

  27. ‘Geez, talk about couch ‘experts about everything’ (the typical private pilot) not having the slightest clue about the bigger picture!!!’

    Well, firstly, it’s an opinion blog.

    Secondly, the blog is about 100LL and its lead-free replacement for GA, how the media views the promises made, promises not kept, the failures to find a solution after seemingly a hundred years – making us look pathetic, the nuanced social interaction with the public and media and their dominant attitudes about GA, and the inattention collectively we seem to be enjoying while our passion for flight and its freedoms seems to be in a mushing stall, slowly losing altitude every day.

    Since you completely missed both points, I am not surprised you would demean and belittle those members of GA who the blog was actually directed toward trying to make aware. Disgusting.

    • Yep…. and you’re the reason that these thing need to be said… I didn’t miss any point. Some people can’t see the forest for the trees even when holding a chain saw sadly!

  28. When I was a boy, I thought like a boy…..Whoa?….That’s not what I wanted to say….must have been all that scrolling down I had to do just to add my comment here!

    What I want to say is: do you not find it interesting that this discussion about unleaded avgas evolved into a rather defensive critique of the value of GA?

    Maybe we pilots need to do do a little more thinking about our worth to our society. Maybe we have become too focused on ourselves. Maybe we need to intellectually reinvest in ourselves as pilots and in our GA community at large.

    I like the idea suggested by the person above who suggested that we could come together as a community of sorts to promote new awareness about GA (What? come together in these times?). I also agree that just moving to unleaded avgas is not enough. Can’t you hear all those tree-hugger catcalls of, “What took you so long?”.

    Very recently, the traveling public jumped all over the airlines for a wide array of failures – in fact, they still have Southwest in their sights. Many ingredients mixed together to deliver this miasma, but the one message we continued to hear was “pilot shortage”. Let’s not debate their message, but rather ask from where do airline pilots emerge. Where do they come from?

    Oh! I remember now! When I was a boy, the airline pilots came from the armed forces and there was a surplus to choose from. Not anymore. Today, these pilots primarily raise up from our ranks in GA. But where have all the flight schools gone (“…longtime passing….”)? Are we responsible for their demise? What have you personally done to support the EAA Young Eagles program? How many airshows do you take young kids to? Are we failing to stimulate young dreams that often lead to aviation careers? GA is the fertile field of aviation dreams that creates pilots that feed the airlines. That is a serious asset for our society, but we have kept it a secret from the public. If the public understood that airline availability and performance was directly related to pilot (and mechanic) availability, and that pilots “grow-up” in GA, perhaps we would enjoy more public respect. “Hey! We can’t close that airport! They’re training pilots there.”

    Moving on. What national phenomenon has dominated our news broadcasts more than inflation? And we know we can ride the damn bus if we have to, but we certainly cannot stop eating! Food prices have risen dramatically. Ever visit the Central Valley in California or the miles of crop fields in southern Texas, Arizona, and Florida? The wheat, meat, and potatoes might travel by rail, but the crop dusters are a “must have” for the fruit and vegetable growers. Should we be talking more in the media and Congress about these highly competent members of our flying community and their role in relieving food prices?

    As a child, I watched “Sky King” on TV. Certainly, between the pipeline patrols, the air evac industry, the crop dusters and the airborne fire fighters, we could promote some simple entertainment for child TV – Ahh, back to that dream again! Right now, the only thing available for the kiddies is a questionable show about a group of daredevils who go around performing aircraft repos from criminals. We can certainly improve our public image beyond that.

    What about business aviation? Are we promoting that toxic public image of the CEO boarding the GIII with his wife and golf clubs? Perhaps it’s time we helped the public adjust their perception of business aviation by demonstrating publicly (like on TV…) how effective unscheduled, on-demand transportation with business amenities (communication systems, etc.) allows business leaders to work so much more effectively.

    Unleaded avgas will do way more for my O-360 Lycoming health than it will do for the air breathed by young children, but it is a positive step forward. BTW. Stay tuned. It is going to happen much sooner than you think. In the meantime, consider what we can do for ourselves…without an STC or spending a penny. Help spread the word about the qualities of your GA.

    • I remember an episode of Sky King where super sonic booms were an issue and it was resolved some how and helicopter noise (coffee grinders) didn’t bother the uncle who was the cook? 27 hours of crop dusting dumps 1 pound of lead into the environment, it has to settle somewhere. 10 billion dollars of infrastructure aid to 99 airports, doesn’t increase sky space, it only adds to the saturation.

  29. “On the other hand, why? We’ve committed to eliminate TEL yet, at an industry level, we resist it kicking and scratching all the way.”

    That is the question isn’t it?

    If you eliminate circumferential narratives from the discussion, the beginning and end of this hand-wringing is found in the lack of engagement by Continental and Lycoming.

  30. One commenter said it so well. “lack of engagement by Continental and Lycoming”. And its not just them! Ram, and a ton of other STC holders have mods to INCREASE compression ratios or effective ratios (turbocharging) for a particular airframe’s engine. This is the wrong way to go. Then there is AVIC, who can’t seem to put their own JetA engines in their own airframes (Cirrus). The Cirrus fleet is flying so many hours right now, and the airframer and the operators don’t seem to realize the precariousness of their choices. There is only ONE manufacturer of TEL, and they could shut down tomorrow, and make all of our studies a mute point. We are acting like we are completely ignorant of the physical facts. The U.S. military realized the weaknesses, dangers, and supply chain issues of leaded gasoline many years ago.

  31. It is sad to hear about UND’s choice to remain with leaded avgas. The economy of scale for 94UL would have greatly benefited from the large fleet operation. Paul, you have written a great article and we appreciate you.

  32. I think the only way an unleaded 100 octane will be produced in volume is with the same kind of legislation that rejuvenated Cessna production of single engine planes. As have been pointed out before aviation gasoline is a specialty product with high liability attached to it. Just as Cessna once said they wished all of their older planes would just go away, I would not be surprised if the oil companies in the US probably aren’t that interested in developing or producing a new low volume aviation product, only to have to deal with even more liability than they do now.