|Site Weiach, Switzerland|
Number of deaths 46
Date 14 November 1990
Passenger count 40
|Summary Controlled flight into terrain due to ILS receiver failure|
Similar Alitalia Flight 112, Indian Airlines Flight 605, Alitalia Flight 771, SANSA Flight 32, 1990 Wayne County Ai
Alitalia Flight 404 (AZ404/AZA404) was a scheduled international passenger flight, flown by Italian national airliner Alitalia's McDonnell Douglas DC-9-32 aircraft from Linate Airport in Milan, Italy to Zurich International Airport, Zurich, Switzerland. On 14 November 1990, the aircraft crashed into the woodlands of Weiach while approaching Zurich Airport. All 46 people on board died.
The investigation finally concluded that the cause of the accident was due to the faulty ILS receiver of the DC-9 and other several navigational problems. Poor crew resource management was also noted as one of the contributing factors of the crash. Due to the accident, the Swiss authority upgraded its navigational system in every airport in Switzerland. The DC-9 was about 16 years old at the time of the accident and had accumulated 33,886 hours in the air.
During the approach to runway 14 of the Zurich airport, the pilot's ILS display gave false values due to a faulty receiver and showed about 1,000 feet of additional altitude and a centered glide slope, even though it flew much too low. The ILS receiver of the co-pilot was working correctly and was showing the dangerously low approach. Despite this, the captain decided – without thoroughly examining which was the correct value – to ignore the second device. A go-around maneuver initiated by the co-pilot was aborted by the captain. Shortly afterwards, at 19:11 CET, the plane struck the Stadlerberg mountain at 1,660 ft. All 40 passengers and six crew perished in the accident.
Contributing to the accident was that the crew descended below 4,000 ft QNH, without clearance, before reaching the Final Approach Fix, and that air traffic control did not notice this descent.
Reviewing the chain of events, the investigation board made several recommendations in order to avoid similar scenarios. Improved rules for communication among pilot and co-pilot during landing have been implemented as well as possibilities of misreading flight altimeters have been pointed out. Most importantly, new rules prohibit the abortion of a go-around once it has been initiated, regardless of the rank and function of the crew member initiating the go-around. Proper review of decisions and clear communications are, since a long time, part of the so-called Crew Resource Management.