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Accident
Last updated: 29 July 2016
Statuts:Enquête Officielle
Date:mardi 6 février 1996
Heure:23:47
Type/Sous-type:Silhouette image of generic B752 model; specific model in this crash may look slightly different
Boeing 757-225
Opérant pour:Alas Nacionales
Loué à :Birgenair
Immatriculation: TC-GEN
Numéro de série: 22206/31
Année de Fabrication: 1985
Heures de vol:29269
Cycles:13499
Moteurs: 2 Rolls-Royce RB211-535E4
Equipage:victimes: 13 / à bord: 13
Passagers:victimes: 176 / à bord: 176
Total:victimes: 189 / à bord: 189
Dégats de l'appareil: Détruit
Conséquences: Written off (damaged beyond repair)
Lieu de l'accident:26 km (16.3 milles) NE de Puerto Plata, Dominican Republic (   Océan Atlantique)
Phase de vol: En vol (ENR)
Nature:Charter International
Aéroport de départ:Puerto Plata-La Union International Airport (POP/MDPP), République Dominicaine
Aéroport de destination:Gander Airport, NF (YQX/CYQX), Canada
Numéro de vol:ALW301
Détails:
Flight ALW 301 departed Puerto Plata for a charter flight to Frankfurt via Gander and Berlin at 23:42 LT. At 80 knots on takeoff the captain found out that his air speed indicator (ASI) wasn't working properly. The co-pilot's indicator seemed to work fine. While climbing through 4700 feet the captain's ASI read 350 knots (real speed was about 220 kts); this resulted in an autopilot/autothrottle reaction to increase the pitch-up attitude and a power reduction in order to lower the airspeed. At that time the crew got 'Rudder ratio' and 'Mach airspeed' advisory warnings. Both pilots got confused when the co-pilot stated that his ASI read 200 knots decreasing while getting an excessive speed-warning, followed by a stick shaker warning. This led the pilots to believe that both ASIs were unreliable.
Finally realizing that they were losing speed and altitude they disconnected the autopilot. The autopilot, fed by the captain's faulty ASI, had reduced the speed close to the stall speed. Full thrust was then applied. At 23:47:17 an aural GPWS warning sounded. Eight seconds later the aircraft struck the ocean.
The incorrect ASI readings were probably caused by the obstruction of the pitot system by mud and/or debris from a small insect that was introduced in the pitot tube during the time the aircraft was on the ground. The aircraft was not flown for 20 days before the crash and was returned for service without a verification of the pitot-static system as recommended by Boeing.


PROBABLE CAUSE: "The crew's failure to recognize the activation of the stick shaker as a warning of imminent entrance to the stall, and the failure of the crew to execute the procedures for recovery from the onset of loss of control."

Sources:
» Air Safety Week 12.02.1996 (p. 1)
» Aviation Week & Space Technology 12.02.96(33,34)
» Flight International 14-21.02.96(4)
» NTSB Safety Recommendations A-96-15 through -20
» Erroneous Airspeed Indications Cited in Boeing 757 Control Loss (Flight Safety Foundation - Accident Prevention October 1999)

Official accident investigation report
cover
investigating agency: DGAC Dom. Rep.
report status: Final
report number: Final report
report released:25 October 1996
duration of investigation: 262 days (9 months)
download report: Final report

Opérations de secours

NTSB issued 6 Safety Recommendations

Show all AD's and Safety Recommendations

Photos

photo of Boeing 757-225 TC-GEN
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Plan
Ce plan montre l'aéroport de départ ainsi que la supposée destination du vol. La ligne fixe reliant les deux aéroports n'est pas le plan de vol exact.
La distance entre Puerto Plata-La Union International Airport et Gander Airport, NF est de 3524 km (2203 miles).

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