The aircraft departed Derby Aerodrome at 08:10 GMT for a scheduled passenger service to Glasgow, via Leeds/Bradford Airport. During the flight to Leeds/Bradford, the crew received the 07:50 GMT weather report for Leeds, which indicated visibility 1200 metres and 8/8 cloud at 100 ft., in rain. This report was confirmed shortly before arrival over the aerodrome, when Leeds/Bradford ATC passed the current weather report as follows: wind at 070ø/10-12 kts; visibility 4 kms, but subject to rapid fluctuations down to about 1200 metres; 8/8 cloud, base between 100 and 200 ft. The captain decided to land on runway 33, which afforded the longest available landing distance (3,650 ft.), and was equipped with approach lighting and a VASI installation. At about 08:45 GMT, shortly after passing over the Leeds/Bradford NDB, the pilot was informed that the cloud base, measured by balloon, was 200 ft., and he was then cleared to commence a PPI continuous-descent approach to runway 33. On final approach, the aircraft broke cloud at a height of about 250 ft., and the approach was continued by visual reference. Following a normal touchdown at a point about mid way between the threshold and the intersection with runway 01/19, the pilots found that application of the wheel brakes had no appreciable effect. On realising that the aircraft would not stop before reaching the runway end, the captain initiated a swing to the left, in order to avoid workmen on the runway extension. The aircraft ran off the runway onto rough ground, and then bounced a distance of about 95 ft. before landing heavily on a mound of earth. This caused both main landing gears to collapse. Examination of the aircraft showed that the wheel brakes were capable of developing the required braking power at the time of the accident. Both main tyres showed signs of scuffing and thin blistering, and the tracks at the tyres on the runway were discernible as whitish discolorations. The depth of water standing on the runway in the vicinity of the tyre marks was subsequently found to vary between 0.05 and 0.20 inches. Tests carried out on a localised area of runway 33 showed that the co-efficient of friction of the runway surface was lower than average. It was concluded that the accident resulted from loss of brake effectiveness due to aquaplaning during the initial part of the landing run, and subsequent low braking force values.