Aviation Fuel & Environmental Issues

The Octane Problem

Piston aircraft engines are designed to run at extremely high compression ratios and power outputs — far beyond what a car engine produces relative to its size. They need fuel that resists detonation (knocking) under extreme conditions: high altitude, high temperatures, and sustained full-power operation during takeoff and climb. Lead (specifically tetraethyl lead, or TEL) is the additive that provides this detonation resistance. Without it, engines can experience destructive detonation that leads to catastrophic engine failure — in flight.

Why Not Just Use Car Gas?

Some lower-compression aircraft engines can use automotive fuel (mogas) with an STC. But the majority of the GA fleet — including most Cessnas, Pipers, Beechcraft, and Cirrus aircraft — have high-compression engines that require 100-octane fuel. Automotive premium is only 91-93 octane. Running these engines on lower-octane fuel risks detonation, which in an airplane means the engine can fail when you need it most — on takeoff, in the mountains, or over terrain with no place to land.

The Scale of the Issue

Context matters. In Colorado's 2023 fiscal year:

To put this in perspective: Colorado drivers consume 2.23 billion gallons of motor gasoline annually. Avgas consumed by the entire GA fleet — every piston airplane in the state — represents just 0.14% of that volume. For every gallon of avgas burned, Colorado cars and trucks burn roughly 700 gallons of motor fuel.

This doesn't minimize the lead issue — even small amounts of lead matter, especially near airports. But it provides critical context: the aviation community is actively working toward a solution for a fuel source that is a fraction of a fraction of total consumption. The challenge is doing it safely.

Source: U.S. Energy Information Administration · CDOT Division of Aeronautics

Colorado Lead Study (May 2024)

The Colorado Department of Public Health & Environment found that children living near Colorado airports showed slightly elevated levels of lead in their blood. However, levels remained within the range the federal government considers normal.

Sources: Colorado DPHE · CDC Blood Lead Reference Value · NIEHS Geospatial Analysis

Do You Live Near Enough to a Small Airport to Have Lead Exposure?

Interactive mapping tool showing proximity-based lead exposure risk from aviation fuel at small airports across the United States.

Quartz · June 2022

U.S. Standards for Lead Levels

CDC/ATSDR reference for understanding what blood lead levels mean and the current regulatory thresholds.

CDC Agency for Toxic Substances and Disease Registry

EPA Endangerment Finding (October 2023)

The EPA released its final aviation gasoline emission endangerment finding, formally determining that lead emissions from piston-engine aircraft cause or contribute to air pollution that endangers public health. This finding is the regulatory foundation for the transition to unleaded fuel.

The Honest Position

Pilots don't want to burn leaded fuel. No one in aviation is defending lead as a good thing. The challenge is that the replacement must be safe — truly safe, not just politically expedient. An unleaded fuel that causes engine failures would trade one public health concern for another, far more immediate one. The transition must be done right, and it must be done based on engineering data, not legislative timelines.

EAGLE: Eliminate Aviation Gasoline Lead Emissions

EAGLE is the industry-government partnership to eliminate leaded avgas by the end of 2030 (2032 for Alaska) without compromising the safe and efficient operation of the GA fleet. The phased approach includes fuel authorization, market demonstration, fleet-wide transition, and full compliance.

flyeagle.org →

Grant Assurance 40

Federally funded airports must maintain 100LL availability through December 31, 2030, or until an FAA-authorized unleaded alternative becomes widely available. Airports that ban 100LL prematurely risk losing federal funding.

California 100LL Ban (2031)

Governor Newsom signed SB1193, banning leaded aviation gasoline effective 2031 — the first state-level 100LL prohibition in the U.S. Passed 59-11 in the House and 30-8 in the Senate.

Santa Clara County Ruling (2025)

The FAA ruled that Santa Clara County's 2022 prohibition on 100LL sales violated federal airport grant obligations. AOPA and other organizations filed the complaint. The county was granted an extension but the ruling established that local bans cannot supersede federal aviation authority.

Colorado: Jefferson County Airport Lawsuit (2024)

Rocky Mountain Metropolitan Airport (KBJC) was sued by Superior, CO residents over noise and lead contamination. This case highlights the tension between airport communities and surrounding development — a pattern seen at airports nationwide.

FAA Part 150: Airport Noise Compatibility Planning

14 CFR Part 150 is the federal framework for airport noise planning. It establishes procedures for developing noise exposure maps and noise compatibility programs. Airports can voluntarily participate in Part 150 studies to identify noise-sensitive areas and develop mitigation strategies — but the key word is "voluntarily." Local governments cannot impose their own noise rules that conflict with federal aviation authority.

FAA Airport Noise Compatibility Planning

The 65 DNL Standard

The FAA uses Day-Night Average Sound Level (DNL) as the primary noise metric. Areas exposed to 65 DNL or higher are considered incompatible with residential use. However, this metric averages noise over 24 hours — meaning a few loud events can be masked by long quiet periods. Many residents feel the metric doesn't capture their actual experience of airport noise.

What Pilots Can Do

Good neighbor practices make a real difference. CPA encourages pilots to:

• Follow published noise abatement procedures at your home airport
• Avoid unnecessary low-altitude flight over residential areas
• Use runway headings and published departure/arrival procedures
• Minimize pattern work during early morning and late evening hours
• Report noise complaints to your airport's noise office, not social media
• Engage constructively with community noise forums when they occur

Colorado Airport Noise Resources

Centennial Airport (KAPA) maintains a revised Noise Exposure Map and active noise abatement program. CPA's Practice Areas page includes noise abatement overlays for the Denver metro area.

See also: CO Rep. Shannon Bird Presses CDPHE on Leaded Avgas from RMMA (YouTube)

Electric Training Aircraft Coming to Colorado

Centennial Flyers has ordered six Bristell B23 Energic all-electric training aircraft — the first all-electric training fleet planned for Colorado. Electric aircraft produce zero emissions, minimal noise, and lower operating costs for flight training.

December 2025

The Battery Challenge

The low-altitude electric aviation market is projected to reach nearly $30 billion by 2030, but aviation-grade battery systems remain a critical hurdle. Safe batteries require multilayer containment, active fault detection, and thermal isolation — standards that don't yet exist at scale.

Nature · September 2025