In 2003, JetBlue Airways (NASDAQ: JBLU) shocked industry observers by ordering Embraer‘s (NYSE: ERJ) new 100-seat E190 jet. This departed from the accepted wisdom that low-cost carriers should stick to operating a single aircraft type in order to keep costs down. (JetBlue primarily flies Airbus (NASDAQOTH: EADSY) A320-family aircraft.)