Denver International Airport
Aircraft Accident/Incident Report

Denver, Colorado 80249
Tuesady, July 31, 2012 9:09 MDT

NTSB Narrative Summary Released at Completion of Accident

The flight crew reported that the airplane struck a bird while descending to land. Examination of the airplane after the event revealed a large hole in the radome and a portion of the broken radome lodged on the left pitot tube, which was also bent. The flight crew reported that following the bird strike, the captain’s airspeed and altimeter were inoperative and the first officer’s airspeed and altimeter indications were erratic. The captain eventually lost all instrument indications on his primary flight display (PFD). The crew referenced the standby instruments, but the readings did not make sense given the airplane altitude and power settings. As a result, the flight crew used power settings and aircraft configurations along with air traffic control (ATC) callouts of their ground speed to continue the flight to the intended destination, where they executed an uneventful landing. The operator later reported that the standby airspeed indicator readings during the descent appeared to match the ground speed callouts provided by ATC. Data retrieved from the flight data recorder (FDR) for the left air data inertial reference unit (ADIRU), which references sensed data from the left pitot probe and static ports, confirmed a loss of airspeed information that would have resulted in an amber flag indicating “IAS DISAGREE” on the left and right primary PFD, as well as an amber flag indicating “SPD” on the left PFD. Data from the right ADIRU and the standby system were not recorded. Other air data parameters exhibited erroneous behavior that was consistent with the loss of airspeed information. The FDR continued to record altitude and attitude information throughout the remainder of the flight. Testing of the air data systems following replacement of the damaged pitot tube and cleaning of the system did not reveal any malfunctions or failures that would explain the total loss of indications on the left PFD.

NTSB Probable Cause Narrative

An in-flight collision with a bird during descent to land, which resulted in damage to the left pitot tube and loss of airspeed information to the left and right primary flight displays (PFD). The reason for the total loss of indications on the left PFD could not be determined based on available evidence.

Event Information

Type of Event Incident
Event Date 7/31/2012
Event Day of the Week Tuesday
Time of Event 909
Event Time Zone Mountain Daylight Time
Event City Denver
Event State COLORADO
Event Country --
Zipcode of the event site 80249
Event Date Year 2012
Event Date Month 7
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude 395142N
Event Location Longitude 1044023W
Event Location Airport Denver International Airport
Event Location Nearest Airport ID DEN
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles 45
Degrees magnetic from airport --
Airport Elevation 5434
Weather Briefing Completeness --
Investigator's weather source Weather Observation Facility
Time of the weather observation
Direction of event from weather observation facility (degrees) 330
Weather Observation Facility ID DEN
Elevation of weather observation facility 5434
Distance of event from weather observation facility (units?) 45
Time Zone of the weather observation --
Lighting Conditions Day
Lowest Ceiling Height 20000
Lowest Non-Ceiling Height 12000
Sky/Lowest/Cloud Conditions Few
Sky Condition for Lowest Ceiling Broken
Visibility Runway Visual Range (Feet) --
Visibility Runway Visual Value (Statute Miles) --
Visibility (Statute Miles) 10
Air Temperature at event time (in degrees celsius) 23
Dew Point at event time (in degress fahrenheit) 11
Wind Direction (degrees magnetic) 220
Variable Wind Indicator Wind direction could be determined
Wind Speed (knots) 19
Wind Velocity Indicator --
Wind Gust Indicator Gusting
Wind Gust (knots) 26
Altimeter Setting at event time (in. Hg) 30.17
Density Altitude (feet) --
Intensity of Precipitation --
METAR weather report ##################################################
Event Highest Injury None
On Ground, Fatal Injuries --
On Ground, Minor Injuries --
On Ground, Serious Injuries --
Injury Total Fatal --
Injury Total Minor --
Injury Total None 157
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 32359
NTSB Notification Source FAA-ANM-ROC
NTSB Notification Date --
NTSB Notification Time --
Fiche Number and/or location -used to find docket information --
Date of most recent change to record Dec 12 2013 4:24PM
User who most recently changed record brajo
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N37420
NTSB Number CEN12IA502
Missing Aircraft Indicator --
Federal Aviation Reg. Part Part 121: Air Carrier
Type of Flight Plan filed IFR
Flight plan Was Activated? Yes
Damage Minor
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name BOEING
Aircraft Model 737-924ER
Aircraft Series Identifier --
Aircraft Serial Number 33457
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 191
Number of Engines 2
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 CONTINENTAL AIRLINES INC
Aircraft Owner Street Address --
Aircraft Owner City HOUSTON
Aircraft Owner State TX
Aircraft Owner Country USA
Aircraft Owner Zipcode 77002-7362
Operator is an individual? No
Operator Name UNITED AIR LINES INC
Operator Same as Owner? No
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? --
Certified for Part 133 or 137 Operation --
Operator Certificate Number UALA011A
Indicates whether an air carrier operation was scheduled or not Scheduled
Indicates Domestic or International Flight Domestic
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 DFW
Departure City Dallas
Departure State TX
Departure Country USA
Departure Time 818
Departure Time Zone CDT
Destination Same as Local Flt --
Destination Airport Code --
Destination City Denver
Destination State CO
Destination Country USA
Specific Phase of Flight --
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Jan 15 2014 4:44PM
User who most recently changed record brajo
Since inspection or accident --
Event Location Runway Number and Location 26
Runway Length 12000
Runway Width 150
Sight Seeing flight No
Air Medical Flight No
Medical Flight --