Independent Air Flight 1851

Independent Air Flight 1851

Accident summary
Date	8 February 1989
Type	Controlled flight into terrain
Site	Pico Alto, Santa Maria Island, Azores
Passengers	137
Crew	7
Fatalities	144 (all)
Survivors	0
Aircraft type	Boeing 707-331B
Operator	Independent Air
Tail number	N7231T
Flight origin	Bergamo-Orio al Serio Airport, Italy
Stopover	Santa Maria Airport, Santa Maria, Azores
Destination	Punta Cana, Dominican Republic

In 1989, Independent Air Flight 1851, a Boeing 707-331B on an American charter flight from Bergamo, Italy to Punta Cana, Dominican Republic, struck Pico Alto on approach to Santa Maria Airport in the Azores for a scheduled stopover. The aircraft was destroyed with the loss of all passengers and crew.

Accident

During final approach to Santa Maria Airport, the airport controller instructed that the aircraft should descend to 3,000 feet (914 m) for a runway 19 ILS approach. In that transmission, a trainee controller had also transmitted an incorrect QNH (barometric altimeter) setting that was 9 hPa too high. The approach instructions were briefly unheard since the pilot had re-keyed his microphone to acknowledge the new QNH, and likely did not hear the second repeat of the 3,000 ft (914-m) safe altitude, declaring: "We’re re-cleared to 2,000 feet..." (610 m). Although the first officer questioned the barometric altitude, the captain agreed that the first officer had heard the read-back correctly.

After being cleared to the ILS approach, the crew failed to accomplish an approach briefing, missing an opportunity to notice the 3,000 ft (914-m) minimum safe altitude and the presence of Pico Alto.

Leveling off at 2,000 ft (610 m), the airliner experienced light turbulence at 250 knots (288 mph; 463 km/hr) and heavy turbulence at 223 knots (256 mph; 413 km/hr) at 700 ft (213 m) near Santo Espírito.

The airliner was level as it impacted the ridge of Pico Alto, colliding with a rock wall on the side of a road at an altitude of 1795 ft (547 m). There was no evidence of an in-flight emergency and the altimeter was found correctly set to 1027 mb.

Report

The Board of Inquiry determined the accident was due to non-observance by the crew of established operating procedures which led to the deliberate descent of the aircraft to 2000 feet (610 m) when the published minimum sector altitude was 3000 feet (914 m). It also found that the controller had put the aircraft 240 ft (73 m) below that indicated on board the aircraft, exacerbating the original error by the first officer.

Other factors:

• Bad communications techniques on the part of the co-pilot and controller, including the non-adherence to standard phraseology in some of the ground communication.
• Neglecting aerodrome control tower procedures in not requesting a readback of the descent clearance.
• The limited international flying experience of the crew and the airline's deficient crew training that did not include emergency maneuvering techniques for terrain avoidance.
• Non-compliance with AIP Portugal flight plan procedures and authorized routes.

See also

• Air safety

References

• Duke, Thomas A. (February 1995), "Aircraft Descended Below Minimum Sector Altitude and Crew Failed to Respond to GPWS as Chartered Boeing 707 Flew into Mountain in the Azores", Accident Prevention (Flight Safety Foundation) 52 (2): 1–15 
• UK CAA (April 1976), CAA Document 429: World Airline Accident Summary, ICAO 

External links

• Accident description at the Aviation Safety Network
• Photos of N7231T at Airliners.net
• Independent Air Boeing 707 CVR Readout