Serious incident Boeing 737-522 N941UA,
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ASN Wikibase Occurrence # 370458
 
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Date:Friday 28 December 2001
Time:16:31 LT
Type:Silhouette image of generic B735 model; specific model in this crash may look slightly different    
Boeing 737-522
Owner/operator:United Airlines
Registration: N941UA
MSN: 26676/2364
Year of manufacture:1992
Total airframe hrs:27409 hours
Engine model:CFM International CFM56-3
Fatalities:Fatalities: 0 / Occupants: 104
Aircraft damage: None
Category:Serious incident
Location:Chicago, IL -   United States of America
Phase: Unknown
Nature:Passenger - Scheduled
Departure airport:Cedar Rapids Eastern Iowa Airport, IA (CID/KCID)
Destination airport:Chicago-O'Hare International Airport, IL (ORD/KORD)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The Boeing 737 airplane encountered wake turbulence during cruise descent. The captain reported the aircraft was descending from 10,000 feet mean sea level (msl) when he noticed a "subtle vibration" that was followed by the airplane entering an uncommanded roll to the right. The captain reported that he disconnected the autopilot system at approximately 20 degrees right roll, and he regained control of the aircraft using manual control inputs of left rudder and left aileron. The captain stated that he had "complete usage of the rudder" during the recovery. The flightcrew declared an emergency and made an uneventful landing. Aircraft radar track data indicated the incident airplane (UAL Flt 1260) was following a Boeing 777, operated by American Airlines as flight 154 (AAL Flt 154). Both aircraft were en route to Chicago O'Hare International Airport and were flying the same arrival procedure. Both airplanes were maintaining a lateral separation of approximately 8.3 nm or about 97 seconds. AAL Flt 154 began its descent 12.56 nm from KRENA intersection, and 23 seconds later UAL Flt 1260 began its descent 6.23 nm from the intersection. During the uncommanded roll and subsequent recovery, all rudder control surface movements correlated with the position of the rudder pedals. No flight control anomalies were found during the post-incident examination and verification flight test.

Probable Cause: The wake turbulence encounter.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CHI02IA058
Status: Investigation completed
Duration: 2 years and 3 months
Download report: Final report

Sources:

NTSB CHI02IA058

Location

Revision history:

Date/timeContributorUpdates
25-Mar-2024 10:54 ASN Update Bot Added

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