A twin-engined ATR carrying about 50 people takes off from Bari, Italy, on the way to a resort in Tunisia, just across the Mediterranean Sea. About half-way, both engines die and refuse to restart despite multiple attempts. The pilots check their instruments. Everything seems in order except for some warnings about fuel being fed to the engines. Not that they're low on fuel; they have more than enough to complete the flight.
In any case the pilot must ditch about 20 miles from the shore of Sicily. Half the passengers and one crew member die. The fuselage breaks up into three part, the nose and tail sinking at once, and the mid-section with one wing still floating.
The investigation is carried out in astonishing detail. To check for fuel contamination, for instance, they go back to Bari, locate the refueling truck used by the ATR, and run swabs around the top of the tank to check for any contamination, including microbiological.
I'll keep this short. The immediate cause of the accident was that both engines were out of fuel and the tanks were empty. The proximate cause was that an almost identical fuel indicator had been installed after the last one had acted up. But the new indicator was designed for a different model of the ATR and was showing 1700 kg. of fuel when in fact there was none. Evertyhing else that went wrong flowed from that faulty installation.
For instance, believing he still had an abundance of fuel available, the captain did not feather the propellers but necessarily left them spinning during the restart procedure. The slowly rotating propellers added immense drag and slowed the airplane down. Later simulations demonstrated that if the captain had KNOWN he was out of fuel, he would have feathered the props and trimmed the airplane for its most efficient glide. Then it would have reached the nearest airport at Palermo.