Preliminary tests indicate that a little-known icing condition cited in a 1994 plane crash in Indiana might have been present when Comair Flight 3272 crashed Jan. 9 near Detroit, a research meteorologist involved in the testing said Tuesday.
Ben Bernstein of the National Center for Atmospheric Research in Boulder, Colo., told The Enquirer the center is focusing on icing because the data are ''consistent with icing on that aircraft.''
The tests have encompassed dozens of hours. The National Transportation Safety Board (NTSB) also is investigating a wide range of scenarios, including possible malfunctions in the engines, autopilot system and pilot error. None has been officially ruled out.
Mr. Bernstein added that National Weather Service readings in Detroit and Wilmington, Ohio, 15 minutes after the crash indicated that conditions were right for the presence of ''super-cooled large drops'' at 4,000 feet, the altitude at which the Embraer 120 Brasilia prop-plane began to lose control.
Those factors include shallow clouds, and icy conditions in the area that several pilots reported. Also, drizzle was reported at ground level the day the Comair flight crashed in a snow-covered field in Monroe County, Mich., 45 miles outside Detroit, killing all 29 aboard.
Mr. Bernstein said the same super-cooled large drops occurred in Roselawn, Ind., when American Eagle Flight 4284, another prop plane, crashed on Halloween night 1994, killing all 68 aboard.
The Federal Aviation Administration determined that the cause of that accident was a buildup of ice on the wings when the plane entered an area of these super-cooled
large drops.
Mr. Bernstein also was involved in atmospheric tests on that crash.
Super-cooled large drops are an atmospheric oddity. They are liquid despite being as cold as
minus-15 degrees. The drops, likened to freezing drizzle, are suspended, though not necessarily stationary, in clouds.
When an object such as a wing moves through the cloud, the drops can immediately freeze on the surface of the craft, weighing down the plane before inflatable de-icing boots could break them off. They also might affect the plane's propellers.
''Data indicated those clouds could have freezing drizzle aloft, or these super-cooled large drops, but it's still in the early stages so it's yet to be determined,'' Mr. Bernstein said. He said that tests are continuing and that the center will meet with NTSB officials next month to determine the next course of testing.
''These super-cooled drops are a growing concern,'' Mr. Bernstein said. ''We've known about them since the '80s, but we are just becoming more aware. They've probably been a factor before but we didn't know it.''
NTSB spokesman Paul Schlamm declined to elaborate on the preliminary findings Tuesday, though he did confirm that the tests are under way in Boulder.
If icing were present, Mr. Bernstein said, it would have significantly increased the speed necessary to keep the plane from dropping to stall speed. Stall speed is defined as when a plane's wings lose the lift needed to keep the plane flying.
The Comair plane had neared stall speed of 166 mph shortly before the deadly roll began, it has been widely reported.
Ironically, scientists benefited from timing in studying the Comair crash. Every 12 hours, Mr. Bernstein said, the National Weather Service sends atmospheric testing equipment tied to balloons at its many sites, including Detroit and Wilmington.
That 12-hour interval happened to fall at 4 p.m. Jan. 9, just 15 minutes after the crash.
PROFILES OF VICTIMS
COMPLETE COVERAGE
