Narrative:
Before takeoff, the crew of flight UA663 noted cumulus clouds and virga in the area. At 13:27, a de Havilland Canada DHC-7 crew reported a 25 kt loss of airspeed, but several other aircraft then took off without reporting a problem. Due to radio congestion, the captain did not query other aircrews, but decided to climb out at V2 plus 20. when the controller cleared US663 for takeoff, he advised the crew of numerous wind shears in 3 quadrants, but used incorrect terminology in issuing the wind shear alert. During takeoff, the aircraft struck an ILS localizer antenna, 1074 ft from the departure end of the runway, and damaged the lower fuselage. When unable to pressurize the aircraft, the crew returned to the airport and landed.
An investigation revealed the aircraft encountered wind shear from microburst activity which reached its greatest activity as US663 was taking off. The wind sheared from an 8 kt headwind to 40 to 56 kts over a 44 second period. The crew noted a hesitation while accelerating through 120 kts, then at or beyond Vr speed of approx. 141 kts, the aircraft momentarily lost 20 kts.
Probable Cause:
weather condition..windshear
Contributing Factors:
object..approach light/navaid
weather condition..rain
weather condition..high wind
weather condition..gusts
weather condition..unfavorable wind
radio communications..excessive
airport/facilities..inadequate
weather evaluation..inaccurate..pilot in command
information unclear..atc personnel(lcl/gnd/clnc)
Collision with approach or runway lights
Forced landing on runway
| Status: | Accident investigation report completed and information captured |
| Date: | Thursday 31 May 1984 |
| Time: | 13:34 |
| Type: |  Boeing 727-222 |
| Operator: | United Airlines |
| Registration: | N7640U |
| MSN: | 19913/672 |
| First flight: | 1968 |
| Engines: | 3 Pratt & Whitney JT8D-7B |
| Crew: | Fatalities: 0 / Occupants: 7 |
| Passengers: | Fatalities: 0 / Occupants: 98 |
| Total: | Fatalities: 0 / Occupants: 105 |
| Aircraft damage: | Substantial |
| Aircraft fate: | Repaired |
| Location: | Denver-Stapleton International Airport, CO (DEN) ( United States of America)
|
| Phase: | Takeoff (TOF) |
| Nature: | Domestic Scheduled Passenger |
| Departure airport: | Denver-Stapleton International Airport, CO (DEN/KDEN), United States of America |
| Las Vegas-McCarran International Airport, NV (LAS/KLAS), United States of America | |
| Flightnumber: | UA663 |
Before takeoff, the crew of flight UA663 noted cumulus clouds and virga in the area. At 13:27, a de Havilland Canada DHC-7 crew reported a 25 kt loss of airspeed, but several other aircraft then took off without reporting a problem. Due to radio congestion, the captain did not query other aircrews, but decided to climb out at V2 plus 20. when the controller cleared US663 for takeoff, he advised the crew of numerous wind shears in 3 quadrants, but used incorrect terminology in issuing the wind shear alert. During takeoff, the aircraft struck an ILS localizer antenna, 1074 ft from the departure end of the runway, and damaged the lower fuselage. When unable to pressurize the aircraft, the crew returned to the airport and landed.
An investigation revealed the aircraft encountered wind shear from microburst activity which reached its greatest activity as US663 was taking off. The wind sheared from an 8 kt headwind to 40 to 56 kts over a 44 second period. The crew noted a hesitation while accelerating through 120 kts, then at or beyond Vr speed of approx. 141 kts, the aircraft momentarily lost 20 kts.
Probable Cause:
Probable Cause:
weather condition..windshear
Contributing Factors:
object..approach light/navaid
weather condition..rain
weather condition..high wind
weather condition..gusts
weather condition..unfavorable wind
radio communications..excessive
airport/facilities..inadequate
weather evaluation..inaccurate..pilot in command
information unclear..atc personnel(lcl/gnd/clnc)
Accident investigation:
 |
|
Classification:
Windshear/downdraftCollision with approach or runway lights
Forced landing on runway
Sources:
» NTSBPhotos
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 Denver-Stapleton International Airport, CO to Las Vegas-McCarran International Airport, NV as the crow flies is 983 km (614 miles).
Distance from Denver-Stapleton International Airport, CO to Las Vegas-McCarran International Airport, NV as the crow flies is 983 km (614 miles).
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.
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