The Phoenix's take-off was considered too dangerous to stage at the sandy filming location (its actual take-off was from a smoothed, compacted-earth runway), so legendary stunt pilot Paul Mantz was asked to do a "touch-and-go" landing in which he came in low, skimmed his landing gear along the ground, then throttled up to gain altitude, merely simulating a take-off. On the second take, as the landing gear made contact with the ground, the plane's aft boom fractured, causing the aircraft to nose into the ground and cartwheel, killing Mantz. As the second take had merely been a "protection shot," with the necessary footage captured during the first attempt, a vintage North American O-47A observation plane from an air museum was substituted for the remaining necessary close-ups.
James Stewart, playing the pilot Frank Towns, was a highly experienced pilot in real life, having flown many missions in WWII, and was still officially in the United States Air Force Reserve when the film was made.
A surprise failure at the box office, despite its powerhouse cast. In a 1974 interview, director Robert Aldrich opined that it might make back its money "in another five years".
The Phoenix was, in fact, a real cobbled-together plane that actually flew. The cockpit was very spartan, not fully functioning, was very shallow, and was located behind the radial engine, not inside it. There are many videos available that depict the structure and history of the Tallmantz P-1, as the plane was officially called, as well as videos that show the actual crash in which it was destroyed during a filming sequence for The Flight of the Phoenix. This resulted in the death of pilot Paul Mantz, who is eulogized at the end of the film. The aircraft had been built specifically for use in The Flight of the Phoenix.
According to director Robert Aldrich the cast went out at night in Yuma Arizona where the film sets were, driving around and causing mayhem. They used to drive around with prop dummies (used during the crash scene) and throw them out while the car was moving, so bystanders thought they were real people. Jimmy Stewart was the "outsider" wary of the European actors, but soon got in on the fun, taking a prop machine gun and jumping out to finish off the dummies gangland style. The police stopped them, but when they found it was Jimmy Stewart they let them go. It was also Aldrich's and Stewart's futile job to try to keep Peter Finch sober. (source book is "Jimmy Stewart the Truth Behind the Legend")