21 September 2012, #544
A Boeing 737-300 was operating a scheduled passenger flight from Nice (France) to Birmingham (England) with six crew and 137 onboard. The flight from Nice was uneventful with the captain as pilot flying (PF) and the co-pilot as pilot monitoring (PM).
The aircraft in the grass, shortly after coming to a stop (Source; Blogspot.com © Unknown)
During the approach briefing, the auto brake was set to "2" as the crew planned to exit the runway at Taxiway Bravo after landing on runway 33. (see the layout further down in the blog). The runway at Birmingham was wet and the wind was light from an easterly direction. The approach was flown without any abnormalities and the aircraft touched down in the touchdown zone after flying the approach at the correct speed. Reversers were deployed and idle reverse thrust was selected.
As the aircraft decelerated after landing the PF judged it would not be possible to vacate the runway at Taxiway Bravo without excessive braking. The Auto Brake was deselected by pressing the brake pedals, the aircraft was just before Taxiway Bravo. Reversers were stowed a short while later and the PM let the aircraft roll towards the end of the runway, with the intention to vacate the runway via Taxiway Alpha.
Birmingham airport layout (Source; AAIB)
As the aircraft rolled down the runway towards Taxiway Alpha ATC contacted the next aircraft on the approach with the following message;
"EXPECT LATE LANDING CLEARANCE PREVIOUS LANDER HAS GONE ALL THE WAY TO THE END.”
This message was heard by the crew of the Boeing 737, and the captain did not want the other aircraft to have to possibly go around. As the aircraft reached Taxiway Alpha (according to the PF at a speed of 12 knots) The PF started to turn the aircraft to the left. At first, the response was as expected, however, as the aircraft progressed through the turn the aircraft started to skid toward the left side of the taxiway. In an attempt to stop the aircraft from leaving the paved surface of the taxiway the pF applied full foot brakes. This was not enough to stop on the paved surface and the aircraft left the taxiway and came to a stop with all gears on the grass.
The aircraft on the grass (Source; Blogspot.com © Unknown)
Seeing the aircraft turn off the runway ATC cleared the next aircraft to land. Shortly theatre the B737 crew informed ATC that had stopped on the grass, ATC immediately ordered the aircraft on approach to go around. With the aircraft stopped the crew started the APU and shut down the engines. It was quickly established there were no injuries. Mobile passenger steps were brought to the aft service door (Right-hand aft door) and the passengers and crew left the aircraft and were transferred to the terminal by buses. No other aircraft had reported difficulties after landing on runway 33.
The aircraft only suffered dame to the nose wheels which were replaced.
The Air Accidents Investigation Branch (AAIB) was alerted and an investigation was started. The investigation consisted (amongst others) of;
Runway friction tests (which revealed a small area of reduced friction on the exit of the runway connecting to Taxiway Alpha)
Flight Data Recorder and Cockpit Voice Recorder analysis 'The 'Slippery Area' on the taxiway (© AAIB)
It became clear during the investigation that the aircraft was travelling at a speed in excess of 20 knots when the PF initiated the turn of the runway. The Operations Manual for the aircraft stated that a speed of approximately 10 kt should be used for making a turn from the runway onto a non-high-speed taxiway in the dry. The runway and taxiways at Birmingham were wet.
The aircraft back on the taxiway (Source; Blogspot.com © Unknown)
The AAIB concluded that the speed of approximately 10 kt should be used for making a turn from the runway onto a non-high-speed taxiway in the dry. The AAIB report, on which this blog is based, is available for reference and more details by clicking on the .pdf file below;