U.S.W.B. Office the issued SIGMET No 1 at 1430 amending the existing area forecast to conform to the Severe Weather Forecast. The SIGMET, valid from 1430 to 1830 read on part. ". a few severe thunderstorms or isolated tornado in Western New York east of a Buffalo, New York-Williamsport line Locally severe turbulence in thunderstorms and chance of extreme turbulence. Hail of 1-1/2 inches diameter, surface wind gusts to 65 knots in severe thunderstorms. . "
Shortly thereafter, the SIGMET was disseminated over Service A weather teletype. At 1445, the Cleveland Office issued an amended Rochester terminal forecast valid from 1445 to 0100 which mentioned "scattered thunderstorms and a chance of isolated tornadoes" The Mohawk Dispatch Office sent the following teletype message to all Mohawk stations at 1453.
"Post for pilots and pass to any flight into areas mentioned. Weather Bureau Severe Weather Forecast indicates along and 60 miles either side from 60 southeast Buffalo to 50 miles northeast Batavia, scattered severe thunderstorms in extreme turbulence. Hail to 1-1/2 inches in diameter and maximum surface guests 65 knots. Possibility an isolated tornado or two. Squall line forming in Ontario to vicinity Buffalo and Youngstown. Expected to intensify and move eastward at 40 knots. Company Pireps indicates a line of thunderstorms through Western Pennsylvania from north of Johnstown extending southeastward and building rapidly. Expect these thunderstorms to move eastward."
At 1455 Flight 115, N 449A, arrived at Ithaca from New York. The captain of the aircraft then advised Captain Dennis, the pilot assigned to the segment from Ithaca to Rochester on Flight 115, of a squall line approximately 75 to 80 miles northeast of Ithaca and that "it looked pretty bad" The incoming captain testified that he had no prior notification of thunderstorm activity, but after hearing an en route aircraft ahead of him request a rerouting to circumnavigate thunderstorms, he observed the squall line on aircraft radar. He also stated that N 449A operated normally during the flight from New York to Ithaca.
Flight 115 departed Ithaca at 1508. Neither a copy of the flight plan release nor copies of the required weather documents were retained in the Ithaca station file.
- ↑ The Cleveland, Ohio Office is responsible for forecasting the weather in an area encompassing the northern third of Ohio, Western Pennsylvania, and Western New York. Rochester, New York is in their area of responsibility.
- ↑ A SIGMET is a message designed primarily for aircraft in flight, warning of weather conditions potentially hazardous to transport cateegory (and other) aircraft.
- ↑ Oncoming crew members were Captain Richard M. Dennis, First Officer John W. Neff, and Stewardess Mary Ann Miara.
- ↑ Mohawk Airlines Operations Manual 03.04:06 states "All releases shall be prepared in duplicate with the signatures appearing on both copies. Stations shall maintain a copy of each attachment furnished a flight. File copies of all releases shall be kept for a period of three months."