Yesterday there was an AP report of an American Airlines flight that diverted after a passenger who notice a fuel leak on the wing while in flight. He bought it to the crews attention. The aircraft landed safely. The passenger was an air national guard soldier. This is an classic example of CRM, or Cockpit Resource Management which trains flight crews to use all their resources in order to make a good decision. CRM also train crews on problems solving skills, better crew communications, & judgment. But most important, it trains crews to use all their resources. Those resources include other crew members, mechanics, air traffic control, and the passengers. Some passengers that travel frequently know what's normal & abnormal in airline operations & are often the first to point something out. I always remember several years ago a passenger told me information on an electric anomaly he saw on takeoff that helped me to give detail description to our maintenance dept. This information helped my company on fixing the problem & saving the company a lot of money. So, the bottom line is that flight crews do welcome passengers speaking up on safety concerns.