Alitalia Flight 4128 was a scheduled flight from Leonardo da Vinci Airport, in Rome, Italy, to Palermo International Airport in Palermo, Italy, with 129 on board. On 23 December 1978, it crashed into the Tyrrhenian Sea about 3 km (1.9 mi) north of Palermo while on approach. The accident was attributed to the flight deck crew believing they were nearer to the runway than they were, and therefore making a premature descent. The initial part of the approach was instrumental until the flight was 2 miles (3.2 km) from Palermo International Airport. The crew then stopped the descent at 150 feet above the sea, as though trying to locate the final approach area, thinking they were close to the runway because of the airport lights. In the final nine seconds, the aircraft flew almost level with the sea at 150 knots (280 km/h; 170 mph); then, because of the wind, the aircraft lost its final altitude and impacted the water with its right wing. 108 of the 129 passengers and crew on board were killed.

According to what was later stated by some pilots, the accident could have been caused by an optical illusion ("black hole approach") that would have drawn in error the pilots: at night, with particular weather conditions (low altitude cloud cover), runway lights can be reflected on clouds and water, giving the impression that the runway is a few hundred meters before its real location. This optical illusion could have contributed to the accident, together with inadequate lighting and the unavailability of ILS on runway 21. Non-optimal radio communication between crew and ATC introduced further uncertainty about the estimated location of the aircraft.

As a result of the accident, out of 129 people (between passengers and crew), 108 perished and 21 survived, rescued by nearby fishing boats. It is the second-deadliest air crash in Alitalia's history behind Alitalia Flight 112 which had crashed 6 years prior.

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