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Cases › CEN09IA294 · Part 121 airline

BOEING 737SOUTHWEST AIRLINES CO

Houston, TX, USA · 2009-05-13·N371SW

0
fatal
0
serious
Minor injury
highest injury
Minor
damage

What happened

NTSB summary, verbatim

Prior to the flight, the flight crew and dispatcher were aware that the anti-skid system was inoperative. They had requested and were granted use of the longest runway for landing. The captain made a normal landing in the target area. After touchdown, he reduced the thrust levers to idle, rapidly brought the speed brake to the full-up detent, employed reverse thrust, and applied manual wheel braking. Marks on the runway showed that about 550 feet after initial touchdown, the right main landing gear tires blew. The tower controller and other aircraft advised the flight crew that there was a fire in the area of the right main landing gear. After the airplane came to a stop, the captain initiated an emergency evacuation on the runway. All 54 persons on-board exited the airplane in 57 seconds, and the fire was extinguished soon after. Two passengers reported minor injuries. The airplane sustained minor damage to the right main landing gear and a portion of the right flap. Examination of data retrieved from the flight data recorder showed that during the touchdown and landing roll, at 19:45:31, the recorded left brake pressure was 770 pounds per square inch (psi). The maximum recorded right brake pressure was 1430 psi at 19:45:32. The maximum recorded left brake pressure was 990 psi. With the anti-skid system disabled, the pilot applying excessive braking during touchdown would cause the wheels to lock and the associated tires to blow. The airplane's quick reference handbook states "Use minimum braking consistent with runway conditions to reduce the possibility of a tire blowout."

Photographs

18the aircraft, and what the investigators found
The aircraft before the accident
11fr - Southwest Airlines Boeing 737-3H4; N371SW@FLL;30.01.1998 (5198209254)
Aero Icarus from Zürich, Switzerland · CC BY-SA 2.0 · Wikimedia Commons
Wreckage and site documentation · 17 photographs from the docket

Photographs are NTSB docket attachments — works of the US government, in the public domain. Captions are the Board’s own.

Probable cause

the Board's determination
The pilot's inadvertent application of excessive braking after touchdown, which caused the right wheels to lock and several tires to blow and resulted in a subsequent brake fire.

Occurrence sequence

4 stepsNTSB coding · CICTT taxonomy
  1. 1 · Prior to flight
    Miscellaneous/other
  2. 2 · Landing-landing roll
    Fire/smoke (non-impact)
    defining event
  3. 3 · Post-impact
    Fire/smoke (post-impact)
  4. 4 · Post-impact
    Evacuation

Findings

2 causal · 2 contributing
  • CAUSE
    Aircraft › Aircraft oper/perf/capability › Performance/control parameters — Incorrect use/operation
  • CAUSE
    Personnel issues › Action/decision › Action › Incorrect action performance — Pilot
  • FACTOR
    Aircraft › Aircraft systems › Landing gear system › Brake — Not specified
  • FACTOR
    Aircraft › Aircraft systems › Landing gear system › Tire casing — Not specified

Sequence of events

3 timed eventsfrom the FDR factual report · claude-fable-5-1 (in-session)
  1. approach into KHOU (plots 1-2)approachp.3
    Basic, landing gear and brake parameters plotted from just before gear extension to about two minutes after engine shutdown
  2. about 19:45:31-19:45:32 CDTtouchdownp.4
    Touchdown and landing roll: recorded left brake pressure 770 psi at 19:45:31 while the right brake pressure peaked at 1,430 psi at about 19:45:32 (tires blew at touchdown)
  3. 19:45:57 and 19:46:03 CDTlanding rollp.4
    Maximum left brake pressure 990 psi recorded twice during the landing roll; plot 3 ends when ground speed reaches zero

NTSB analysis

from the final report

Prior to the flight, the flight crew and dispatcher were aware that the anti-skid system was inoperative. They had requested and were granted use of the longest runway for landing. The captain made a normal landing in the target area. After touchdown, he reduced the thrust levers to idle, rapidly brought the speed brake to the full-up detent, employed reverse thrust, and applied manual wheel braking. Marks on the runway showed that about 550 feet after initial touchdown, the right main landing gear tires blew. The tower controller and other aircraft advised the flight crew that there was a fire in the area of the right main landing gear. After the airplane came to a stop, the captain initiated an emergency evacuation on the runway. All 54 persons on-board exited the airplane in 57 seconds, and the fire was extinguished soon after. Two passengers reported minor injuries. The airplane sustained minor damage to the right main landing gear and a portion of the right flap. Examination of data retrieved from the flight data recorder showed that during the touchdown and landing roll, at 19:45:31, the recorded left brake pressure was 770 pounds per square inch (psi). The maximum recorded right brake pressure was 1430 psi at 19:45:32. The maximum recorded left brake pressure was 990 psi. With the anti-skid system disabled, the pilot applying excessive braking during touchdown would cause the wheels to lock and the associated tires to blow. The airplane's quick reference handbook states "Use minimum braking consistent with runway conditions to reduce the possibility of a tire blowout."