As of June 2008 the International Air Transport Association has eliminated these, maybe saving a tree or 2
Most 
airlines believe that if allowed by the ministry, they could save costs... [DOC] [TLE] My First Year With Solar - IEEE Spectrum [PAR] Aug 31, 2010 ... Transportation ..... My house in Boulder, Col., is perfectly situated: It has a south-
facing ... and being a relatively new house, it has few trees to block the sun.