United B739 at Denver on Jul 31st 2012, bird strike causes loss of airspeed indications

Last Update: March 25, 2014 / 20:27:05 GMT/Zulu time

Bookmark this article
Incident Facts

Date of incident
Jul 31, 2012

Classification
Accident

Airline
United

Flight number
UA-1475

Aircraft Registration
N37420

Aircraft Type
Boeing 737-900

ICAO Type Designator
B739

A United Boeing 737-900, registration N37420 performing flight UA-1475 from Dallas Ft. Worth,TX to Denver,CO (USA) with 151 people on board, was on approach to Denver's runway 26 level at 12,000 feet when a bird impacted the nose cone of the aircraft causing a large dent and hole underneath the captain's windshield. The crew reported a loud noise from the forward fuselage, the captain had no airspeed indication at all, the first officer's air speed indication was unreliable and requested emergency services at the runway and radar based ground speed readings for cross checks. The aircraft continued for a safe landing on runway 26 about 10 minutes later.

On Aug 14th 2012 the NTSB reported that besides the large hole at the radome a portion of the radome became lodged on the left pitot tube, remains of the large bird were also found within the left engine (CFM56) and on the tail of the aircraft. The crew reported the "pitot static flight instruments in the cockpit were not indicating correctly" so that the crew used pitch and power settings along with aircraft configurations and ATC ground speed call outs.

On Mar 25th 2014 the NTSB released their final report concluding the probable cause of the incident was:

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.

The NTSB reported that following the damage to the left hand pitot tube the flight data recorder recorded the rapid loss of left airspeed, which reduced to 45 KIAS, an amber SPD flag on the left primary flight display and loss of associated indications. The first officer's airspeed and altitude data became erratic (the right hand air data were not recorded). The crew referenced the stand by instruments, but these did not make sense given the aircraft configuration. The crew used pitch and power settings as well as readouts of ground speed by air traffic control to continue for a safe landing. The operator later stated that the standby airspeed indications were consistent with the ground speeds.
Aircraft Registration Data
Registration mark
N37420
Country of Registration
United States
Date of Registration
P lkgnbk g jA Subscribe to unlock
Manufacturer
BOEING
Aircraft Model / Type
737-924ER
Number of Seats
ICAO Aircraft Type
B739
Year of Manufacture
Serial Number
Aircraft Address / Mode S Code (HEX)
Engine Count
Engine Manufacturer
Engine Model
Engine Type
Pounds of Thrust
Main Owner
Gdqff bfmgldhqffbbeqfm lAbbjdmA mihniljAfllccqmn keAhlnkqbl gpmqee fAgcfhAlkAAepifdmgnjildbpqpebichiieef Subscribe to unlock
Incident Facts

Date of incident
Jul 31, 2012

Classification
Accident

Airline
United

Flight number
UA-1475

Aircraft Registration
N37420

Aircraft Type
Boeing 737-900

ICAO Type Designator
B739

This article is published under license from Avherald.com. © of text by Avherald.com.
Article source

You can read 2 more free articles without a subscription.

Subscribe now and continue reading without any limits!

Are you a subscriber? Login
Subscribe

Read unlimited articles and receive our daily update briefing. Gain better insights into what is happening in commercial aviation safety.

Send tip

Support AeroInside by sending a small tip amount.

Related articles

Newest articles

Subscribe today

Are you researching aviation incidents? Get access to AeroInside Insights, unlimited read access and receive the daily newsletter.

Pick your plan and subscribe

Partner

Blockaviation logo

A new way to document and demonstrate airworthiness compliance and aircraft value. Find out more.

ELITE Logo

ELITE Simulation Solutions is a leading global provider of Flight Simulation Training Devices, IFR training software as well as flight controls and related services. Find out more.

Blue Altitude Logo

Your regulation partner, specialists in aviation safety and compliance; providing training, auditing, and consultancy services. Find out more.

AeroInside Blog
Popular aircraft
Airbus A320
Boeing 737-800
Boeing 737-800 MAX
Popular airlines
American Airlines
United
Delta
Air Canada
Lufthansa
British Airways