On this day in 2005, the first hull loss occurred of a Boeing 737-700. Southwest Airlines flight 1248 overran the runway at Chicago Midway Airport.
The aircraft on the 10th of December, only to be moved after the NTSB concluded their onsite investigation. (© Gabriel Widyna)
After a delay of 1 hour and 5 minutes, caused by weather, the Boeing 737-7H4 departed Baltimore / Washington International Airport: destination, Chicago Midway Airport just over 600 miles (975 km) in a straight line. After an uneventful flight, the aircraft had to hold for about 30 minutes.
ATC advised the crew this was due to snow clearing in progress. After receiving clearance to leave the hold the crew was vectored to the 6522 feet (1980 meters) long runway 31C at Chicago Midway Airport. While in the hold the crew had updated the Performance Computer with the latest weather. This resulted in a tailwind component of 8 knots. (Southwest Airlines tailwind limit was 10 knots, However, a limit of 5 knots applied when the braking action was poor.
Using their Performance Computer to go through different scenarios the crew considered various options for fair and poor braking action. The crew was aware of these limits and realised they would have to divert if the braking action was reported as poor.
During the flight and the approach briefing the crew decided to use the auto brake system due to the weather conditions. However, neither flight crew member had used this system previously under these conditions.
The aircraft in its final position (© NTSB)
When contacting Midway Tower ATC the crew received the following information;
Runway 31 C braking action The first half, good - Second half, poor
Wind 090° at 9 knots
Shortly after receiving the landing clearance the aircraft touched down at a speed of 124 knots, on the centerline of the runway. Within one second after touchdown, (a firm touchdown according to the crew) the spoilers deployed and brake pressure increased. The captain reported in the post-accident interview that he had trouble selecting reverse thrust and that he was under the impression the antiskid system had failed and the aircraft was accelerating. The First Officer noticed that the deceleration was decreasing and called for the brakes to be applied, and applied manual braking himself. The Captain still had his hands on the reverse thrust levers, without selecting them. 15 Seconds after touchdown the first officer removed the captain's hand from the reverse thrust levers and selected maximum reverse. 18 seconds after touchdown the thrust reversers were fully deployed.
The aircraft is being readied for removal from the accident site (© NTSB)
This was too late to stop the aircraft on the runway and the aircraft ran off the end of the runway, it continued;
Through the runway safety area
Through a blast fence
Through the localiser antenna
Across an airport road
Through the airport perimeter fence.
Coming to a stop on a public road adjacent to the airport perimeter after striking a car. (one of the occupants of the car, a 6-year-old child, sadly perished in the collision while 4 passers-by received various injuries)
Chicago Midway Airport layout, runway 31C in yellow and final location of aircraft at red dot (Source and © NTSB Report)
An extensive investigation was launched by NTSB and the investigation report gives the following probable cause, from the NTSB report;
"The National Transportation Safety Board determines that the probable cause of this accident was the pilot’s failure to use available reverse thrust in a timely manner to safely slow or stop the airplane after landing, which resulted in a runway overrun. This failure occurred because the pilots’ first experience and lack of familiarity with the airplane’s auto brake system distracted them from thrust reverser usage during the challenging landing." Several contributing factors are also stated in the NTSB report, which can be found by clicking on the .pdf file below;
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