Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Tangshan Switzerland
Friday, July 29, 2011 5:58 UTC
NTSB Narrative Summary Released at Completion of Accident
The flight crew reported a normal takeoff and climbout with a small amount of clouds and rain in the area. The preflight weather briefing package included a forecast of convective activity including a SIGMET (significant meteorological information) for thunderstorms south of the Beijing area moving northeastward. The crew was aware of the potential for convective activity during the climbout from Beijing, and the initial enroute segment over the Bohai Sea. During flight, the Captain was actively using the airborne weather radar to search for convective returns, including using the Doppler functions. Satellite imagery showed a signature termed “transverse banding” which is indicative of thunderstorms and turbulence at altitude. Based on the lack of weather radar returns, the Captain kept the cabin seat belt sign illuminated, but advised the cabin crew that they could begin service. The airplane encountered convectively induced turbulence, resulting in a peak vertical acceleration of over 2 G’s. The activity was likely developing upwards into the flight path, and precipitation attenuation and/or radar over-scanning may have contributed to the lack of visibility of the condition, which led to the risk assessment to allow the flight attendants to begin service.
Following the turbulence encounter, the flight crew controlled the airplane appropriately to avoid an overspeed or other hazardous condition. The flight and cabin crew consulted with a physician passenger and determined continuing the flight per the injured flight attendant’s desire, was appropriate.
NTSB Probable Cause Narrative
an inadvertent encounter with convectively induced turbulence likely due to radar limitations and convective weather developing upwards into the flight path.
Event Information
| Type of Event | Accident |
| Event Date | 7/29/2011 |
| Event Day of the Week | Friday |
| Time of Event | 558 |
| Event Time Zone | Coordinated Universal Time? Same as GMT |
| Event City | Tangshan |
| Event State | -- |
| Event Country | SWITZERLAND |
| Zipcode of the event site | -- |
| Event Date Year | 2011 |
| Event Date Month | 7 |
| 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 | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | -- |
| Elevation of weather observation facility | -- |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | -- |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | -- |
| Sky Condition for Lowest Ceiling | -- |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | -- |
| Air Temperature at event time (in degrees celsius) | -- |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | -- |
| Variable Wind Indicator | -- |
| Wind Speed (knots) | -- |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | -- |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | -- |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Serious |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | 4 |
| Injury Total None | 380 |
| Injury Total Serious | 1 |
| Injury Total All | 5 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 30888 |
| NTSB Notification Source | United |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Jan 2 2013 12:15PM |
| User who most recently changed record | sedj |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N173UA |
| NTSB Number | DCA11FA091 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | Yes |
| Damage | None |
| Aircraft Fire | None |
| Aircraft Explosion | -- |
| Aircraft Manufacturer's Full Name | BOEING |
| Aircraft Model | 747-422 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 24380 |
| Certified Max Gross Weight | -- |
| Aircraft Category | Airplane |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 495 |
| Number of Engines | 4 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | -- |
| Date of Last Inspection | -- |
| Airframe hours since last inspection | -- |
| Airframe Hours | -- |
| ELT Installed | Unknown |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | United Airlines |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | Chicago |
| Aircraft Owner State | IL |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | -- |
| Operator is an individual? | No |
| Operator Name | United Airlines |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | -- |
| Operator City | Chicago |
| Operator State | IL |
| Operator Country | USA |
| 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 | -- |
| 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) | -- |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | PEK |
| Departure City | Beijing |
| Departure State | -- |
| Departure Country | CH |
| Departure Time | -- |
| Departure Time Zone | -- |
| Destination Same as Local Flt | -- |
| Destination Airport Code | KSFO |
| Destination City | San Francisco |
| Destination State | CA |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Apr 3 2012 12:53PM |
| User who most recently changed record | engb |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | N/A |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |