Status: | Accident investigation report completed and information captured |
Date: | Tuesday 6 February 1996 |
Time: | 23:47 |
Type: | Boeing 757-225 |
Operating for: | Alas Nacionales |
Leased from: | Birgenair |
Registration: | TC-GEN |
MSN: | 22206/31 |
First flight: | 1984-02-03 (12 years ) |
Total airframe hrs: | 29269 |
Cycles: | 13499 |
Engines: | 2 Rolls-Royce RB211-535E4 |
Crew: | Fatalities: 13 / Occupants: 13 |
Passengers: | Fatalities: 176 / Occupants: 176 |
Total: | Fatalities: 189 / Occupants: 189 |
Aircraft damage: | Destroyed |
Aircraft fate: | Written off (damaged beyond repair) |
Location: | 26 km (16.3 mls) NE off Puerto Plata, Dominican Republic ( Atlantic Ocean)
|
Phase: | En route (ENR) |
Nature: | Int'l Non Scheduled Passenger |
Departure airport: | Puerto Plata-La Union International Airport (POP/MDPP), Dominican Republic |
Destination airport: | Gander Airport, NL (YQX/CYQX), Canada |
Flightnumber: | ALW301 |
Narrative:Alas Nacionales flight 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:
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."
Accident investigation:
|
Investigating agency: | DGAC Dom. Rep. |
Status: | Investigation completed |
Duration: | 262 days (9 months) | Accident number: | Final report | Download report: | Final report
|
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Classification:
Pitot head issues
Loss of control
Sources:
» Air Safety Week 12 February 1996 (p. 1)
» Aviation Week & Space Technology 12.02.96(33,34)
» Flight International 14-21 February 1996 (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)
Follow-up / safety actions
NTSB issued 6 Safety Recommendations
Issued: 31-MAY-1996 | To: FAA | A-96-15 |
ISSUE AN AIRWORTHINESS DIRECTIVE TO REQUIRE THAT THE BOEING 757/767 AIRPLANE FLIGHT MANUAL BE REVISED TO NOTIFY PILOTS THAT THE SIMULTANEOUS ACTIVATION OF THE "MACH/SPD TRIM" & RUDDER RATIO" ADVISORIES IS AN INDICATION OF AN AIRSPEED DISCREPANCY. (Closed - Acceptable Alternate Action) |
Issued: 31-MAY-1996 | To: FAA | A-96-16 |
REQUIRE THAT THE BOEING COMMERCIAL AIRPLANE GROUP MODIFY THE CREW ALERTING SYSTEM OF THE BOEING 757/767 TO INCLUDE A "CAUTION" ALERT WHEN AN ERRONEOUS AIRSPEED INDICATION IS DETECTED. (Closed - Acceptable Action) |
Issued: 31-MAY-1996 | To: FAA | A-96-17 |
REQUIRE THE BOEING COMMERCIAL AIRPLANE GROUP TO MODIFY IT BOEING 757/767 OPERATIONAL MANUAL TO INCLUDE A DETAILED EMERGENCY PROCEDURE ADDRESSING THE IDENTIFICATION & ELIMINATION OF AN ERRONEOUS AIRSPEED INDICATION. (Closed - Acceptable Action) |
Issued: 31-MAY-1996 | To: FAA | A-96-18 |
ISSUE A FLIGHT STANDARDS INFO BULLETIN TO DIRECT PRINCIPAL OPERATIONS INSPECTORS TO ENSURE THAT THE OPERATING MANUALS OF THEIR BOEING 757/767 OPERATORS INCLUDE A DETAILED EMERGENCY PROCEDURE ADDRESSING THE IDENTIFICATION & ELIMINATION OF AN ERRONEOUS AIRSPEED INDICATION. (Closed - Acceptable Action) |
Issued: 31-MAY-1996 | To: FAA | A-96-19 |
ISSUE A FLIGHT STANDARDS INFO BULLETIN TO NOTIFY PRINCIPAL OPERATIONS INSPECTORS OF THE CIRCUMSTANCES OF THIS ACCIDENT & TO HAVE THEM ENSURE THAT TRAINING PROVIDERS EMPHASIZE THE IMPORTANCE OF RECOGNIZING AN AIRSPEED INDICATION MALFUNCTION DURING THE TAKEOFF ROLL. (Closed - Acceptable Action) |
Issued: 31-MAY-1996 | To: FAA | A-96-20 |
ENSURE THAT ALL BOEING 757/767 TRAINING PROVIDERS INCLUDE AN EFFECTIVE SCENARIO IN THE FLIGHT SIMULATOR DURING WHICH THE STUDENT IS TRAINED TO APPROPRIATELY RESPOND TO THE EFFECTS OF A BLOCKED PITOT TUBE. (Closed - Acceptable Action) |
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Photos
accident date:
06-02-1996type: Boeing 757-225
registration: TC-GEN
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does
not display the exact flight path.
Distance from Puerto Plata-La Union International Airport to Gander Airport, NL as the crow flies is 3524 km (2203 miles).
Accident location: Approximate; accuracy within a few kilometers.
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.