An Analysis of Three Weather-Related Aircraft Accidents

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Two aircraft accidents in 1975, one at John F. Kennedy International Airport in New York City on 24 June and the other at Stapleton International Airport in Denver on 7 August, were examined in detail. A third accident on 23 June 1976 at Philadelphia International Airport is being investigated. Amazingly, there was a spearhead echo just to the north of each accident site. The echoes formed from 5 to 50 min in advance of the accident and moved faster than other echoes in the vicinity. These echoes were photographed by National Weather Service radars, 130–205 km away. At closer ranges, however, one or more circular echoes were depicted by airborne and ground radars. These cells were only 3–5 km in diameter, but they were accompanied by downdrafts of extreme intensity, called downbursts. All accidents occurred as aircraft, either descending or climbing, lost altitude while experiencing strong wind shear inside downburst cells.

1 Department of the Geophysical Sciences, University of Chicago, Chicago, Ill. 60637.

2Atmospheric Physics and Chemistry Laboratory, ERL/NOAA, Boulder, Colo. 80302.

Two aircraft accidents in 1975, one at John F. Kennedy International Airport in New York City on 24 June and the other at Stapleton International Airport in Denver on 7 August, were examined in detail. A third accident on 23 June 1976 at Philadelphia International Airport is being investigated. Amazingly, there was a spearhead echo just to the north of each accident site. The echoes formed from 5 to 50 min in advance of the accident and moved faster than other echoes in the vicinity. These echoes were photographed by National Weather Service radars, 130–205 km away. At closer ranges, however, one or more circular echoes were depicted by airborne and ground radars. These cells were only 3–5 km in diameter, but they were accompanied by downdrafts of extreme intensity, called downbursts. All accidents occurred as aircraft, either descending or climbing, lost altitude while experiencing strong wind shear inside downburst cells.

1 Department of the Geophysical Sciences, University of Chicago, Chicago, Ill. 60637.

2Atmospheric Physics and Chemistry Laboratory, ERL/NOAA, Boulder, Colo. 80302.

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