It is amazing what a technological backwater aviation is.<p>Leaded gas was phased out for cars 40 years ago. They still use leaded gas for piston aircraft and there is no realistic plan to end it.<p>Boeing is still flying the 737 aircraft family from 1968. They still haven't upgraded the control systems to the modern electronic control systems that Airbus and other manufacturers have used since 1988.<p>Any car from 1968 would be illegal to sell in the developed world because it hasn't kept up with emissions, fuel economy, safety and other standards. Incremental changes wouldn't cut it, any nameplate that has lasted that long has had multiple "clean sheet" designs.<p>The same is true for computers, electronics, and most other products.<p>In the case of aviation there is complete regulatory capture. If Boeing doesn't want to upgrade, the FAA doesn't make them. If American Airlines doesn't want to upgrade, the FAA doesn't make them.<p>There is talk of making artificial jet fuel using this failed technology<p><a href="https://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_process" rel="nofollow">https://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_proces...</a><p>Any serious work on green fuels for ground transportation today centers around alcohols, dimethyl ether and other chemicals that are practical to manufacture. The aviation industry can't be bothered to qualify new fuels so we are going to see endless excuses rather than progress in controlling carbon emissions.