This was already tried by a billionaire.

Virgin Atlantic Abandons Ship on Carbon-Saving Plane Towing March 12, 2008 —

With much green fanfare two years ago Virgin Atlantic airways announced its plan to tow planes to the take off runway. Normally planes taxi on their own jet engine power to the runway starting grid they are supposed to take off on. Towing the Virgin planes meant keeping their engines off, thus saving up to two tons of carbon pollution on every flight. Now, it has been discovered the company is reneging on its tow plan and environmental watchdogs are crying “greenwash.”

In December 2006 California Governor Arnold Schwarzenegger gave the green light to Virgin president Sir Richard Branson for the towing plan. But gradually over the past two years Virgin stopped towing their planes because the landing gear is weakened by the towing process. Further, some airports could not accommodate the starting grids necessary for the plan. Virgin, according to a Time of London report, has abandoned its plan.

Environmental organizations are now calling Virgin’s plan a greenwash: advertising green for market share while continuing pollution practices. Jeff Gazzard, board member of the Aviation Environment Federation, told the Times: "Virgin is using bogus green initiatives in an attempt to make passengers feel less guilty about flying and persuade regulators to allow the industry to carry on growing at its present unsustainable rate."