Aircraft overrun
Aircraft overrun
Keywords: Aircraft, Safety
A Cessna 360 Citation landed at Leeds Bradford Airport and overran the end of Runway 14 by a distance of approximately 525ft (160 m), the final 30 ft (10 m)being onto an area of grass. The overrun was as a result of an approach conducted in excess of the recommended speed and, following a late touchdown, a delayed application of the wheel brakes.
The aircraft had arrived in the Leeds area from the south and was vectored towards the left-hand downwind position for an instrument landing system (ILS)approach to Runway 14. At this time the first officer was the pilot flying. As the aircraft neared the airfield, the commander established visual contact and requested a visual approach. The first officer was still the handling pilot, but was given some guidance by the commander during the descent and subsequent turn onto the final approach. At around five miles on the final approach the commander took over as handling pilot and the aircraft was passed a landing clearance by the air traffic control (ATC). At this stage the aircraft was established on the visual glidepath, 3.58 for this runway, in a clean configuration at an airspeed of 220 kt.
The aircraft continued descending on a 3.58 glidepath. At approximately 2 nm from the runway threshold an enhanced ground proximity earning system (EGPWS)Mode 4 “Too Low Terrain” alert was received. With the aircraft at 1.5nm the speedbrake was extended and shortly after this, at a speed of 210 kt,158 of flap was selected. Between 1.5 and 1.0 nm, ATC advised the crew that the landing gear was not down, to which the commander replied “We Know”. The landing gear was then selected down and shortly afterwards, at a speed of 195 kt, full flap was selected. A second “Too Low Terrain” alert sounded twice, but the repeat was interrupted by the autocallout “Minimums”which occurred at 200 feet agl. Immediately afterwards there was one further“Too Low Terrain” aural alert and then a “Sink Rate Sink Rate”alert.
The aircraft began the landing flare in the region of the touchdown zone at a speed of 155 kt, floated or a considerable distance along the runway and then touched down beyond the runway mid-point at a speed of 121 kt. After touchdown the commander applied full reverse thrust, but did not use the wheelbrakes immediately. Wheel braking commenced at around 1,900 ft (585 m) from the end of the paved surface and continued until the aircraft stated to run onto the grass. The aircraft left the paved area at a speed estimated to be 20-30 kt and came to rest in a nose-down attitude. The tail of the aircraft is still in view from the visual control room and ATC activated the crash alarm. The Airport Fire Service were at the scene in 2 min. There were no injuries amongst the passengers or crew and they did not require assistance to vacate the aircraft.
The operational information in the UK Air Pilot (AIP) which was reproduced on the approach charts used by the crew, is that a nuisance EGPWS alert may occur at 2nm final for Runway 14. This is because there is ridge of high terrain at this point. Runway 14 has an undulating profile, starting with a downslope at the touchdown zone which becomes an upslope and then flattens out before again becoming a downslope to the end. Once on the runway in a Citation aircraft or similar, the stop end does not become visible to the pilot until there is around 1,300 ft (400 m) of runway remaining.
The flight log produced by the company operations department at the planning stage contained the following landing information: actual landing distance required 2,733 ft, the distance including a safety factor of 1.6 was 4,537 ft,and runway length 7,300 ft (presumed to refer to the longest available). The runway chart in use by the crew correctly depicted, on the plan view, the paved surface available as 7,380 ft (2,250 m) and in the text showed the longest runway as Runway 32 with a take-off run of 7,180 ft. The LDAs for all runways were also shown on the charts.
Examination and analysis
The aircraft was resting nose down on the grass approximately 12 m beyond the end of the paved surface of Runway 14. The wheels had dug deep furrows into the soft ground and the nosewheel had dug in sufficiently to break free from the nose gear leg. The right wing had impacted the ILS monitoring antenna. knocking it over, and producing a small dent in the leading edge of the right wing. The radome suffered minor damage when it impacted the grass surface after the nosewheel separated. There was also some damage to the main gear doors. The speedbrakes were extended and the flaps were found set to the landing position of 358. There were no skid marks on the end of the runway. The aircraft had logged 755h and it had its last maintenance check on 28 January 2003. No faults were found on the aircraft that might have contributed to the accident.
There were a number of indications to the crew that the approach was not stabilised. First the speed was not reducing at a sufficient rate to enable timely flap selection and flap limit speeds were exceeded. Secondly, there were a number of EGPWS alerts, although the first one may have been as a result of local terrain, there was no response to any of the subsequent alerts. Thirdly,ATC felt that it was necessary to remind the crew about the landing gear on short final approach. Finally, the speedbrakes remained extended throughout the landing whereas the checklist required them to be stowed by 50ft. Some crew interaction or acknowledgement of these events would normally be expected but none was evident.
There are several factors that explain the apparent lack of verbal communication and monitoring of the approach between the two pilots. The rushed nature of the approach and the late deployment of the flap and landing gear together with the EGPWS alerts left little opportunity for standard operating calls or checklists. Also there was a very steep experience gradient between the two pilots; in particular the first officer had very few hours on type whereas the commander had thousands. Furthermore, the commander was directly responsible for the employment of the first officer.
There were several other factors which may have contributed to the accident. The glidepath for Runway 14 at Leeds is unusually steep at 3.58, because of the ridge of high terrain two miles from the runway. This would make it more difficult for an approach which started too high or too fast. To achieve the 3.58 angle of descent at an average groundspeed of 200 kt, as maintained between 5 and 1.5 nm, would require a rate of descent of around 1,250 ft/min which would be unusually high at this stage of approach. Again, because of the terrain, the Runway 14 landing threshold is displaced by 1,020ft (311 m) leaving an LDA of 5,912 ft (1,802 m), considerably shorter than the actual paved surface. The company flight plan did not reflect this as the only runway distance quoted therein was the longest available at 7,300 ft, although the correct information was available on the approach plates used by the crew. Though it is possible that the 7,300 ft was the figure in the mind of the commander, leading him to believe that the landing distance was longer than it actually was.
