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Cases › DCA12IA113 › The analyst

BOEING 737-3H4SOUTHWEST AIRLINES CO

What the docket says, assembled. No language model is involved, so nothing on this page can be invented — every line traces to a recorder, a report page or the Board's own record.

8
timed facts
8
precedents
7
passages to ask

Ask the docket

passages, not paraphrases
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Every answer is a passage of the docket with the page it came from, or the words “not in the docket”. Nothing is summarised or reasoned for you — read the source.

One timeline

8 timed factsthe recorder events from the FDR report, with the transcript's warnings, callouts, the words nearest each event and the final seconds — on one clock, as printed in each report
  1. about 12:41 MDTFDRtakeoffp.3
    Aircraft departed and climbed to flight level 370
  2. about 13:35 MDTFDRdescentp.3
    Descent for El Paso began
  3. 14:00:39-14:00:45 MDTFDRapproachp.3
    At 7,836 ft pressure altitude the landing gear transitioned from up and locked to down and locked (gear lock parameters sampled only once every 4 seconds); coincident with the last sample of nose gear up and locked, the master caution sampled one warning at 14:00:39
  4. after 14:00:45 MDTFDRapproachp.3
    Aircraft descended to about 4,240 ft pressure altitude (about 600 ft radio altitude) heading east
  5. about 14:04:47 MDTFDRgo-aroundp.3
    Aircraft began a climb to about 4,900 ft pressure altitude while turning right
  6. about 14:07:15 MDTFDRapproachp.3
    Aircraft began to descend while turning right back toward an easterly heading
  7. about 14:08:33 MDTFDRlandingp.3
    Vertical acceleration fluctuated between 1.24 g and 0.79 g in under one second
  8. 14:08:41 MDTFDRlandingp.3
    Nose gear weight-on-wheels transitioned from air to ground, about 8 seconds after the acceleration fluctuation
Flight Data Recorder 10 - Specialist's Factual Report · 8 events extracted by claude-fable-5-1 (in-session)
How the Board coded the sequence
  1. Approach: Aircraft structural failure→
  2. Approach: Miscellaneous/other

Precedents

8 closest casesranked by what happened, in the Board's words, and by the findings and occurrences it coded
  • CEN11IA3412011-05-17no fatalitiesmatch 53
    BEECH 1900D · Great Lakes Aviation
    Denver, CO
    • ●Aircraft › Aircraft handling/service › Maintenance/inspections
  • ENG10IA0162010-01-07no fatalitiesmatch 49
    DOUGLAS DC8 · ASTAR AIR CARGO INC
    Cincinnati (CVG), OH
    Aircraft structural failure
  • ENG08IA0422008-10-01no fatalitiesmatch 48
    BOEING 737 · Southwest Airlines, Co.
    Chicago, IL
    Aircraft structural failure
  • DCA16LA0962016-02-12substantialmatch 48
    LOCKHEED 382G · Lynden Air Cargo
    Iliamna, AK
    • ●Aircraft › Aircraft handling/service › Maintenance/inspections
    Aircraft structural failure
  • DCA12IA0962012-06-17no fatalitiesmatch 46
    AIRBUS A320 · JETBLUE AIRWAYS CORPORATION
    Las Vegas, NV
    • ●Aircraft › Aircraft handling/service › Maintenance/inspections
  • DEN05LA0772005-05-14substantialmatch 45
    McDonnell Douglas MD-88
    Denver, CO
    matched on what happened, as the Board wrote it · same aircraft family
  • ENG09IA0092009-07-15no fatalitiesmatch 45
    BOEING 737-3B7 · US AIRWAYS INC
    Charlotte (CLT), NC
    Aircraft structural failure
  • CHI06FA1582006-06-20substantialmatch 43
    McDonnell Douglas DC-9-83
    Chicago, IL
    matched on what happened, as the Board wrote it · same aircraft family

What the record says

a pattern, not a findingacross the 8 closest cases · 6 carry coded findings · 8 have a probable cause
Findings the Board cited in those cases
Occurrences it coded
  • 4 of 8Aircraft structural failure
  • 2 of 8Landing gear collapse
Set against the Board’s own findings for this case
Cited here, and common in the precedents
  • Aircraft handling/service › Maintenance/inspections
Cited here, not seen in the precedents
  • Fluids/misc hardware › Misc hardware
Common in the precedents, not cited here
  • Aircraft systems › Landing gear system

A teaching device, not a verdict: what the record would have looked at, next to what the Board found.

In the Board’s words — the closest cases
  • CEN11IA3412011-05-17 · BEECH 1900D · Great Lakes Aviation
    The fatigue failure of the nose landing gear (NLG) end cap, which resulted in insufficient hydraulic pressure to secure the left main landing gear into the down and locked position. Contributing to the fatigue failure was the NLG end cap’s non-optimum grain direction and the inadequate inspection procedure performed during overhaul.
  • ENG10IA0162010-01-07 · DOUGLAS DC8 · ASTAR AIR CARGO INC
    Failure of the NLG cylinder occurred by intergranular rupture; coincidental to a chrome plating crack. The failure origin occurred along the inner surface of the cylinder and then propagated by stress corrosion cracking to the outer surface. A secondary crack with the same features as the primary crack was found diagonal to the primary crack. Both cracks initiated by intergranular cracking due to grinding burns caused by abusive grinding and propagated by stress corrosion cracking. Hydrogen embrittlement did not co…
  • ENG08IA0422008-10-01 · BOEING 737 · Southwest Airlines, Co.
    The right nose landing gear axle's failure from intergranular and fatigue cracking due to an earlier bearing failure.
  • DCA16LA0962016-02-12 · LOCKHEED 382G · Lynden Air Cargo
    The fatigue failure of the forward pressure bulkhead canted web that originated from stress corrosion cracking areas. Contributing to the failure were inspection procedures and intervals inadequate to identify the crack.
  • DCA12IA0962012-06-17 · AIRBUS A320 · JETBLUE AIRWAYS CORPORATION
    the failure of the right main landing gear door retraction flexible hydraulic line in the Green hydraulic system, which led to prolonged operation of the power transfer unit and subsequent overheating and loss of pressure in the Yellow hydraulic system, resulting in the airplane's operation with only one hydraulic system. Contributing to the incident was the lack of incorporation of aircraft manufacturer service bulletins that describe procedures for aircraft modifications intended to prevent this occurrence.
What it recommended after them
  • A-13-004TO THE HAWKER BEECHCRAFT CORPORATION: Determine the fatigue life (life limit) of the Beechcraft 1900D nose landing gear (NLG) end cap with the longitudinal grain direction both aligned and not aligned with the longitudinal axis of the NLG. · CEN11IA341Open - Acceptable Response
  • A-13-005TO THE HAWKER BEECHCRAFT CORPORATION: Develop and implement a replacement program for all Beechcraft 1900D nose landing gear end caps based on the fatigue life determined in Safety Recommendation A-13-04. · CEN11IA341Open - Acceptable Response
  • A-13-006TO THE HAWKER BEECHCRAFT CORPORATION: Revise the Beechcraft 1900D nose landing gear end cap repetitive inspection procedure and time interval to ensure that fatigue cracks are detected prior to failure and issue updated guidance to operator… · CEN11IA341Open - Acceptable Response

This is the pattern in the NTSB’s own record across similar accidents — which findings it cited, what it coded, what it recommended. It is drawn from the record, not written about this case, and it never assigns blame: investigations exist to prevent the next accident (ICAO Annex 13).