G-OLTN, a Shorts SD 3-60-100, was operating a scheduled passenger flight between Leeds/Bradford and Bristol on this day in 1989.
Shorts SD 3-60-100, G-OLTN in March 1989 The aircraft had come in from Glasgow (Scotland) to Leeds/Bradford were a crew change took place, no entries were made in the Aircraft Technical Log, although some throttle stagger was verbally reported from one crew to the other. The aircraft was refueled according the flight plan, FOB 1710 kg. Aircraft weights and Center of Gravity were all within aircraft limitations section of the Aircraft Flight.
At 16.50lt the aircraft took off and set course via the cleared routing for Bristol. While in cruise the weather for the destination was obtained and recorded. After several other transfers the flight contacted Bristol Radar who updated the weather info;
· Wind 200/15
· Visibility 16 km
· Clouds 6/8 Cumulo-numbus at 4000’ & 7/8 at 6000’
· Temperature 11
· QNH 989
· Runway Wet
3 view drawing of the Shorts SD 3-60 (from public domain)
Shortly after that the crew received information that heavy thunderstorm was to the east of the airport. To avoid the weather the crew was offered a 5 mile finals to runway 27, which the crew accepted.
The approach was briefed, with minimums at 200 feet, Vref was determined as 98 knots, due to the turbulence the crew aimed for an approach at Vref +10 (108 knots) At 17.51 lt the crew reported established on the ILS and received their landing clearance, with the latest wind reported as 230/18. From 1400 feet the commander flew the aircraft manually. When the commander flared the aircraft a gust of wind hit the aircraft causing a heavy touchdown, bouncing the aircraft back in to the air. On the second hard touchdown a loud bang was heard from the nose landing gear, immediately followed by a Nose Landing Gear unsafe warning. After the aircraft came to a stop on the nose section of the fuselage, as it was not possible to taxi the aircraft was shutdown on the runway. ATC was informed about the situation, and the ATC controller declared a full emergency. The passengers disembarked and were taken to the terminal by bus, there were no injuries to passengers and crews.
When the aircraft was lifted the nose gear came down and locked down. An inspection however revealed damage to the nose landing gear assembly which under loading would cause the landing gear to unlock and retract. Metallurgical examination of the failed nose landing gear component revealed a failure as result of an overload condition, caused by the second touchdown.
He FDR data was analysed as part of the investigation and gave the following information, a clear answer to the question what caused the heavy touchdown;
· Torque difference between the the two engines as result of the reported throttle stagger
· Fluctuating airspeed, possibly as result of the wind conditions
· Nose down demands shortly before touchdown (positive indication on FDR graph)
· Aircraft touched down at a 4º nose down attitude
· Vertical acceleration recorded at 2.2g (1st touchdown) and 1.8g (2nd touchdown)
FDR Data from the AAIB report (©AAIB UK)
The full report from the Air Accident Investigation Branch can be read by clicking here.
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