Some of the proposed alternatives to traditional engine design offer fuel savings that aren't that much greater than auto makers believe they can achieve through improvements to the designs they know.
But he does not think it is worthwhile to re-engine the aircraft because the savings would be tiny compared with the extra costs of having two different engines on a fleet of aircraft.
That would transform the highest tax most working people pay into a personal family wealth engine that over a lifetime of savings and investment would accumulate to close to a million dollars in real terms for two-earner average income families.