Boeing 737-924ER incident near Denver, Colorado, July 31, 2012
On July 31, 2012 at about 3:09 pm local time, a Boeing 737-924ER, registered N37420, suffered minor damage in an incident during enroute (descent) near Denver, Colorado (Denver International Airport). It was flown under scheduled airline rules (Part 121). No one was hurt; 157 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 31, 2012 · about 3:09 pm local time
- Place
- Denver, Colorado · Denver International Airport · map
- Type
- Incident
- Injuries
- No one was hurt; 157 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Boeing 737-924ER · all 737-924ERs on the register
- Registration
- N37420 · registry record · serial 33457
- Damage
- Minor damage
- Flight
- Flight · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Birdstrike during enroute (descent) defining event
The NTSB's findings
- cause Environmental issues › Physical environment › Object/animal/substance › Animal(s)/bird(s) › Effect on operation
Pilot
- Certificate: airline transport pilot, flight engineer
- Ratings: multi-engine land; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 20,000 hours in all; 220 in the last 90 days; 80 in the last 30 days; 10,000 as pilot in command; 1,500 on instruments
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: left
- Injury: no injuries
Co-pilot
- Certificate: airline transport pilot, commercial pilot, flight engineer, military
- Ratings: multi-engine land; single-engine land; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 9,000 hours in all; 70 in the last 90 days; 70 in the last 30 days; 3,000 as pilot in command
- Last flight review: June 1, 2012
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Seats: 191
- Landing gear: retractable
- Engine 1: Cfm Intl CFM56-7B26 (turbofan); 0 hours total
- Engine 2: Cfm Intl CFM56-7B26 (turbofan); 0 hours total
- Operator: United Air Lines INC
The flight
- Departed from: DFW Dallas TX at 1:18 pm
- Destination: Denver CO
- Flight plan: IFR
- Runway 26, 12,000 ft by 150 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 220° at 19 knots, gusting 26
- Visibility: 10 statute miles
- Sky: broken clouds at 20,000 ft; a few clouds at 12,000 ft
- Temperature: 73°F (23°C), dew point 52°F (11°C)
- Altimeter: 30.17 inHg
- Observation at 8:53 am from DEN, 45 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Cabi | 4 | |||
| Flight crew | 2 | |||
| Passengers | 151 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.