NLM CityHopper Flight 431
PH-CHI, the aircraft involved in the accident, is seen here at Euroairport. (1979)
|Date||6 October 1981|
|Summary||Structural failure in severe turbulence|
|Aircraft type||Fokker F-28-4000|
|Flight origin||Rotterdam Airport|
NLM CityHopper Flight 431 refers to a Fokker F-28-4000, registration PH-CHI, that was due to operate an international scheduled Rotterdam–Eindhoven–Hamburg passenger service. On 6 October 1981, the aircraft encountered severe weather on the first leg, minutes after taking off from Rotterdam Airport, and crashed 15 miles (24 km) south-southeast of Rotterdam. All 17 occupants of the aircraft – 13 passengers and crew of 4 – perished in the accident.
The aircraft involved in the accident was a Fokker F28-4000, registration PH-CHI, that was built in 1979 with c/n 1141. At the time of the accident the airframe had accumulated 4485 flight hours and 5997 cycles.
Description of the accident
During the weather briefing 44 minutes before takeoff, the crew was apprised to an area of strong thunderstorms with 3/8 (37.5%) sky coverage of cumulonimbus at a base of 1,200 feet (370 m), south-southwest winds 15 to 25 knots (28 to 46 km/h; 17 to 29 mph) strong, and 5 kilometres (3.1 mi) visibility at Rotterdam Airport. The aircraft took off at 5:04 p.m. CET (UTC +1) from Rotterdam Airport. The crew noted heavy rain in thunderstorms on the airplane's weather avoidance radar at 5:09 p.m., receiving clearance to avoid the area. At 5:12 p.m. the aircraft entered a tornado while flying through clouds. The weather system the aircraft entered into was apparently the same “tornado-like” system that Zeeland locals described as being responsible for considerable property damage. Meteorologically, these vortices are indeed tornadoes, and the disintegrating airliner was seen exiting cloud cover. A police officer first photographed the tornado, then smoke from the burning plane a few minutes later. An investigation concluded that a sharp increase in altitude registered on the altimeter was not a change in altitude, rather a pressure drop associated with the tornado.
Stresses experienced by the airframe owing to severe turbulence resulted in loads of +6.8 g and -3.2 g causing the starboard wing to detach. The aircraft spun down into the ground from 3,000 ft (910 m), crashing some 400 m (1,300 ft) from a Shell chemical plant on the southeastern outskirts of Moerdijk. All 17 occupants of the aircraft –  – perished in the accident.
- "Commercial flight safety: 1981 reviewed – Fatal accidents: scheduled passenger flights". Flight International: 183. 23 January 1982. Archived from the original on 29 July 2013.
- Accident description at the Aviation Safety Network. Retrieved on 14 November 2011.
- "F.28 crashes in bad weather". Flight International: 1127. 17 October 1981. Archived from the original on 29 July 2013.
- Grazulis, Thomas P. (2001). The Tornado: Nature's Ultimate Windstorm. Norman, OK: University of Oklahoma Press. pp. 260–1. ISBN 0-8061-3258-2.
- Roach, W.T.; J. Findlater (Feb 1983). "An Aircraft Encounter with a Tornado". Meteorological Magazine (London: Meteorological Office) 112 (1327): 29–49.
- "F.28 wing loss followed severe turbulence". Flight International: 1124. 17 October 1981. Archived from the original on 29 July 2013.