Southwest Flight 1248

SOUTHWEST AIRLINES FLIGHT 1248

20051208-0-C-d-3-750.jpg 20051208-0-C-d-4-750.jpg
Southwest 1248, Embedded from[http://aviation-safety.net/photos/accidents/750/20051208-0-C-d-3-750.jpg] on 30 September 2010 Southwest 1248, Embedded from[http://aviation-safety.net/photos/accidents/750/20051208-0-C-d-4-750.jpg on 30 September 2010

SYNOPSIS

This accident happened on the 8th December, 2005 at Chicago Midway International Airport, Illinois. The Boeing 737 -700, which was scheduled to from Baltimore to Chicago, to Salt Lake City and then to Las Vegas, slid off the runway at Chicago Midway International airport while landing in a snowstorm. This accident highlighted how delayed flight crew actions combined with poor environmental conditions can result in tragic consequences.

HOW DID IT HAPPEN?

On the day of the departure, the aircraft’s departure out of Baltimore – Washington International was delayed due to weather. After circling for more than 30 minutes, the flight was cleared to land on runway 31 C at Midway Chicago. The available landing distance for the runway was 6522 feet. The runway was covered in snow at the time of landing.

The alternate options available to the flight crew were to hold till the weather improved or to divert to another airport with substantially longer runways.
The flight crew opted for an auto braking setting at “max”. The approach speed recorded was 120 knots and 132 knots. The aircraft landed 2500 feet passed the runway threshold leaving 4500 feet of runway left to decelerate. The captain reported that he couldn’t select reverse thrust. The first officer noticing that the reverse thrust was not deployed selected the reversers 18 seconds later without any problems. Noticing that the deceleration was not normal, the flight crew applied maximum manual braking. The aircraft left the end of the runway, ran through a blast fence and the airport boundary fence, onto a roadway and collided with cars at an intersection just beyond. A child travelling as a passenger in one of the vehicles was killed. There were no on board injuries or fatalities.

NTSB ANIMATION:

(Video embedded from YouTube on 30 september 2010)

CAUSES:

LATENT ERRORS:

  • Failure of the airline to provide its flight crew with guidance and training with regards to the company’s procedures and policy relating to landing distance calculations.
  • The failure of its onboard performance computer due to its programming and design, which didn’t present critical information in spite of the inconsistent wind and thrust reversers assessment methods.
  • The airline’s plan to implement a new auto brake procedure without a familiarisation period. This allows for ambiguity and different interpretations on the part of the flight crew.
  • Failure of the policies and procedures to include a margin of safety to account for operational uncertainties.
  • The absence of engineering materials arresting systems (EMAS), which was required due to the shortened RESA at the end of runway 31C due to the location of the airport in the built up urban area.

ACTIVE ERRORS:

  • Goal conflicts - There is some evidence that the crew were under the influence of “press-on-itis”. The delay incurred by the flights departure and the psychological pressure to complete their flight led to the decision to land in unfavourable conditions.
  • Unanticipated consequences - The flight crew didn’t use all available thrust reversers in time to slow the aircraft after landing. His may be due to the increase in stress experienced by the flight crew.
  • Underestimating risk - The decision to land and the landing itself, landing long in poor runway conditions (contaminated runway).

NTSB RECOMMENDATIONS:

  • The requirement to ensure that all onboard electronic devices used clearly and automatically displays all critical performance calculations.
  • To ensure that a procedure is in place where the pilot monitoring is required to check and confirm the status of the thrust reversers immediately after landing.
  • To endure that airlines provide clear guidance and training to its flight crew on how surface conditions and braking reports affect landing distance calculations.
  • To ensure that all operators utilise an arrival landing distance calculation assessment using a standardised method, using the most conservative interpretation, including a safety margin of 15% for every landing.
  • To immediately prohibit operator from using thrust reversers credit in landing performance calculation for a more conservative figure.

REFERENCES

1. Southwest Flight 1248. Retrieved 30 September, 2010 from http://en.wikipedia.org/wiki/Southwest_Airlines_Flight_1248.

2.Southwest 1248. Retrieved 30 September, 2010 from http://aviation-safety.net/database/record.php?id=20051208-0.

Want to know more?

Wikipedia:http://en.wikipedia.org/wiki/Southwest_Airlines_Flight_1248

Aviationa Safety Network: http://aviation-safety.net/database/record.php?id=20051208-0


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