Aircraft Accident/Incident Report

Port Heiden, Alaska 99549
Tuesady, December 12, 2000 16:21 AST

NTSB Narrative Summary Released at Completion of Accident

A Boeing B-747 airplane departed San Francisco for Hong Kong. Prior to departure, no significant meteorological notices or forecasts for turbulence were issued for the area of the Alaska Peninsula, over which the flight would progress. The airplane was initially in radio and data link communications with Oakland ARTCC, then ARINC, and finally with Anchorage ARTCC. A PIREP at 1432 for moderate turbulence, and an Urgent PIREP at 1600 of severe turbulence, were recorded in the area of incident by Anchorage ARTCC. As the flight entered the Alaska ARTCC area, a delay in establishing communications with the airplane also delayed the transmission of the urgent PIREP concerning turbulence in the area of the flight. The crew noticed rolling clouds ahead of the airplane and advised the cabin flight attendants to be seated. At 1620, while in cruise flight at 31,000 feet, the airplane encountered moderate to severe turbulence. About 5 seconds after the notification to sit down, three cabin attendants were thrown to the floor of the airplane. The captain diverted the flight to Anchorage. Upon arrival at Anchorage, a belly mounted fuselage panel enclosing an air conditioning unit, was missing. Airplanes conducting oceanic flights are equipped with ACARS, over which flight crews can receive ATC clearances and weather data utilizing controller/pilot data link communications (CPDLC). The Anchorage ARTCC was not utilizing CPDLC because their software is not user friendly, requires substantial controller input for free text messaging, and is not as fast as voice communications. Hazardous inflight weather advisories are reviewed by each center weather coordinator, in conjunction with the National Weather Service for dissemination to pilots. The FAA does not a direct mechanism to alert air crews of significant weather in one sector, occurring in another sector, nor does the FAA have a mechanism to coordinate CPDLC data from an ARTCC sector to ARINC. A SIGMET for occasional turbulence was issued by the National Weather Service at 1619.

NTSB Probable Cause Narrative

An encounter with severe turbulence while in cruise flight. Factors in the incident were a delay in notification of the turbulence, and the lack of controller/pilot data link communications in the Anchorage ARTCC area.

Event Information

Type of Event Incident
Event Date 12/12/2000
Event Day of the Week Tuesday
Time of Event 1621
Event Time Zone Atlantic Standard Time
Event City PORT HEIDEN
Event State ALASKA
Event Country --
Zipcode of the event site 99549
Event Date Year 2000
Event Date Month 12
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude --
Event Location Longitude --
Event Location Airport
Event Location Nearest Airport ID
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation --
Weather Briefing Completeness Unknown
Investigator's weather source Pilot
Time of the weather observation 0
Direction of event from weather observation facility (degrees) 0
Weather Observation Facility ID
Elevation of weather observation facility 0
Distance of event from weather observation facility (units?) 0
Time Zone of the weather observation
Lighting Conditions Dusk
Lowest Ceiling Height 0
Lowest Non-Ceiling Height 0
Sky/Lowest/Cloud Conditions Unknown
Sky Condition for Lowest Ceiling Unknown
Visibility Runway Visual Range (Feet) 0
Visibility Runway Visual Value (Statute Miles) 0
Visibility (Statute Miles) 0
Air Temperature at event time (in degrees celsius) -54
Dew Point at event time (in degress fahrenheit) --
Wind Direction (degrees magnetic) 145
Variable Wind Indicator Unknown
Wind Speed (knots) 60
Wind Velocity Indicator Unknown
Wind Gust Indicator Unknown
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) 29
Density Altitude (feet) --
Intensity of Precipitation Unknown
METAR weather report --
Event Highest Injury Minor
On Ground, Fatal Injuries 0
On Ground, Minor Injuries 0
On Ground, Serious Injuries 0
Injury Total Fatal --
Injury Total Minor 4
Injury Total None 386
Injury Total Serious --
Injury Total All 4
Investigating Agency NTSB
NTSB Docket Number (internal use) 10835
NTSB Notification Source --
NTSB Notification Date Dec 12 2000 12:00AM
NTSB Notification Time 1702
Fiche Number and/or location -used to find docket information IMAGE
Date of most recent change to record Nov 1 2001 7:36AM
User who most recently changed record NTSB\MONR
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N119UA
NTSB Number ANC01IA022
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 121: Air Carrier
Type of Flight Plan filed IFR
Flight plan Was Activated? --
Damage Minor
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name Boeing
Aircraft Model 747-422
Aircraft Series Identifier 747-422
Aircraft Serial Number 28812
Certified Max Gross Weight 878000
Aircraft Category Airplane
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 368
Number of Engines 4
Fixed gear or retractable gear Retractable
Aircraft, Type of Last Inspection Continuous Airworthiness
Date of Last Inspection Nov 20 2000 12:00AM
Airframe hours since last inspection 3
Airframe Hours 7949
ELT Installed Yes
ELT Activated No
ELT Aided Location of Event Site Unknown
ELT Type --
Aircraft Owner Name UNITED AIRLINES INC.
Aircraft Owner Street Address 1200 E. ALGONQUIN ROAD
Aircraft Owner City ELK GROVE
Aircraft Owner State IL
Aircraft Owner Country
Aircraft Owner Zipcode 60007
Operator is an individual? --
Operator Name
Operator Same as Owner? Yes
Operator Is Doing Business As --
Operator Address Same as Owner? Yes
Operator Street Address
Operator City
Operator State
Operator Country
Operator Zip code
Operator Code UALA
Owner has at least one certificate Yes - certificate holder
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation Unknown
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not Scheduled
Indicates Domestic or International Flight International
Operator carrying Pax/Cargo/Mail Passenger Only
Type of Flying (Per_Bus / Primary) Unknown
Second Pilot on Board Yes
Departure Point Same as Event No
Departure Airport Code KSFO
Departure City SAN FRANCISCO
Departure State CA
Departure Country
Departure Time 1237
Departure Time Zone AST
Destination Same as Local Flt --
Destination Airport Code VHHH
Destination City HONG KONG
Destination State OF
Destination Country
Specific Phase of Flight Cruise
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Sep 26 2001 4:00AM
User who most recently changed record dbo
Since inspection or accident --
Event Location Runway Number and Location 0
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --