NLM CityHopper Flight 431

NLM CityHopper Flight 431

PH-CHI, the aircraft involved in the accident, is seen here at Euroairport. (1979)
Accident summary
Date	6 October 1981 (1981-10-06)
Type	Structural failure in severe turbulence[1]
Site	near Moerdijk 51°42′N 4°31′E / 51.7°N 4.517°E / 51.7; 4.517Coordinates: 51°42′N 4°31′E / 51.7°N 4.517°E / 51.7; 4.517
Passengers	13
Crew	4
Fatalities	17 (all)
Survivors	0
Aircraft type	Fokker F-28-4000
Aircraft name	Eindhoven
Operator	NLM CityHopper
Tail number	PH-CHI
Flight origin	Rotterdam Airport
Stopover	Eindhoven Airport
Destination	Hamburg Airport

NLM CityHopper Flight 431 referes 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 its flightpath while en route its first leg, minutes before taking off from Rotterdam Airport, and crashed. All 17 occupants of the aircraft —13 passengers and a crew of 4— perished in the accident.^[1][2]

Description of the accident

The aircraft took off at 5:04 p.m. CET (UTC +1) from Rotterdam Airport.^[2] 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.^[2] At 5:12 p.m. the aircraft entered a tornado while flying through clouds.^[2] The weather system the aircraft entered into was apparently the same “tornado-like” system that Zeeland locals described as the responsible for considerable property damage.^[3] Stresses experienced by the airframe owing to severe turbulence resulted in loads increasing to +6.8 g and -3.2 g, and caused the stardboard wing to get detached.^[2][4] The aircraft spinned down into the ground from 3,000 ft (910 m), crashing some 400 m (1,300 ft) from a Shell chemical plant, near Moerdijk.^[3] All 17 occupants of the aircraft —of whom nine were German, five were Dutch, two were British, and one was American^{[citation needed]}— perished in the accident.^[2] One person on the ground, an emergency responder, died of a heart attack.^{[citation needed]}

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.^{[citation needed]}

Weather

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 1200 feet (365 m), winds 210° at 15 - 25 knots (17 - 29 mph; 28 - 46 km/h), and 5 kilometres (3.1 mi) visibility at Rotterdam Airport.

Turbulence

The ICAO turbulence definitions, including the supplementary g loading – positive or negative, relative to the normal 1 g load, are:

• Light - Changes in accelerometer readings less than 0.5g at the aircraft center of gravity.
• Moderate – 0.5 to 1.0 g – Occupants feel definite strains against seat belts. Food service and walking are difficult
• Severe – More than 1.0g – Aircraft may be out of control for short periods. Occupants are forced violent against seat belts. Food service and walking impossible
• The term "Extreme" is not used in Europe

References

1. ^ ^{a b} "Commercial flight safety: 1981 reviewed – FATAL ACCIDENTS: SCHEDULED PASSENGER FLIGHT" (PDF). Flight International: 183. 23 January 1982. http://www.flightglobal.com/pdfarchive/view/1982/1982%20-%200185.html. Retrieved 14 November 2011. 
2. ^ ^{a b c d e f} Accident description at the Aviation Safety Network. Retrieved on 14 November 2011.
3. ^ ^{a b} "F.28 crashes in bad weather" (PDF). Flight International: 1127. 17 October 1981. http://www.flightglobal.com/pdfarchive/view/1981/1981%20-%203215.html. Retrieved 14 November 2011. 
4. ^ "F.28 wing loss followed severe turbulence" (PDF). Flight International: 1124. 17 October 1981. http://www.flightglobal.com/pdfarchive/view/1981/1981%20-%203212.html. Retrieved 14 November 2011. 

External links

• Accident details at planecrashinfo.com