# NTSB DCA96IA005: Boeing B-737-500, N904UA, San Francisco, CA, October 29, 1995

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: October 29, 1995, 12:49 local (20:49 UTC)
- Place: San Francisco, CA
- Location: 37.7750° N, 122.4194° W: Placed by OpenAirDocs: center of San Francisco, CA, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=37.7750&lon=-122.4194&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report November 30, 2007
- Report: Approved by Office Director
- NTSB office: Major Investigations Division
- NTSB case key (mKey): 11005
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA96IA005
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/11005/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=11005
- Page: https://openairdocs.org/ntsb/DCA96IA005

## Probable cause

The inadvertant stall for undertermined reasons.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of control - in flight, go-around (vfr)
  - stall - inadvertent, flightcrew
  - reason for occurrence undetermined (cause)

## Analysis

On October 29, 1995, at 1239 PST, a United Airlines Boeing 737-500, N904UA, experienced an upset during a maintenence test flight while on an ILS approach to San Francisco International Airport (SFO).  The upset occurred when the flight crew was given a go-around by approach control and the captain selected the takeoff and go-around switch.  The airplane pitched up to about 45 degrees nose up and the stick shaker activated.  The pilots stated that they pushed the control column forward and both attempted to retrim the nose down but were not able to overcome the increase in pitch.  The airplane stalled, rolled slightly, and the nose dropped.  After the flightcrew recovered from the upset, the airplane made a normal landing at SFO.

## Factual narrative

On October 29, 1995, at 1239 PST, a United Airlines Boeing 737-500, N904UA, experienced an upset during a maintenence test flight while on an ILS approach to San Francisco International Airport (SFO).  The upset occurred when the flight crew was given a go-around by approach control and the captain selected the takeoff and go-around switch.  The airplane pitched up to about 45 degrees nose up and the stick shaker activated.  The pilots stated that they pushed the control column forward and both attempted to retrim the nose down but were not able to overcome the increase in pitch.  The airplane stalled, rolled slightly, and the nose dropped.  After the flightcrew recovered from the upset, the airplane made a normal landing at SFO.

## Aircraft

- Registration: [N904UA](https://openairdocs.org/deregistered/N904UA-2013-03-21), registration cancelled 2013-03-21, S/N 25004, built 1990 (OpenAirDocs)
- Reported make and model: BOEING B-737-500
- Registry model: [Boeing 737-522](https://openairdocs.org/model/boeing-737-522) (registry code 138449F) (OpenAirDocs)
- Registry engine: [CFM International CFM56 series](https://openairdocs.org/engine/cfm-international-cfm56-series) (registry code 13802, turbo-fan) (OpenAirDocs)
- Category: Airplane
- Engines: unknown
- Damage: No damage
- Fire: Unknown
- Flight: Part 91
- Operator: United Airlines
- Departed: SFO
- Flight plan: VFR/IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; medical: unknown, unknown

## Weather

- Conditions: Instrument (IMC), Not reported
- Visibility: 3 statute miles
- Lowest ceiling: 800 ft overcast
- Temperature: 57 °F, dew point 54 °F
- Altimeter: 29.00 inHg

## Docket (4 files)

The files NTSB released with the investigation on March 22, 1996, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=11005. 2.3 MB in all.

- Systems 9A - Factual Report of Group Chairman - Horizontal Stabilizer Main Trim Actuator Examination (item 1, .PDF, 92 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40449758&FileExtension=.PDF&FileName=Systems%209A%20-%20Factual%20Report%20of%20Group%20Chairman%20-%20Horizontal%20Stabilizer%20Main%20Trim%20Actuator%20Examination-Master.PDF
- Flight Data Recorder 10A - Factual Report of Group Chairman (item 2, .PDF, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40449759&FileExtension=.PDF&FileName=Flight%20Data%20Recorder%2010A%20-%20Factual%20Report%20of%20Group%20Chairman-Master.PDF
- Cockpit Voice Recorder 12A - Factual Report of Group Chairman (item 3, .PDF, 415 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40449760&FileExtension=.PDF&FileName=Cockpit%20Voice%20Recorder%2012A%20-%20Factual%20Report%20of%20Group%20Chairman-Master.PDF
- Cockpit Voice Recorder 12B - Addendum A (item 4, .PDF, 111 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40043779&FileExtension=.PDF&FileName=Cockpit%20Voice%20Recorder%2012B%20-%20Addendum%20A-Master.PDF

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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