And while ice is widely speculated to have had something to do with the crash of a Cessna Citation 560 in Pueblo, Colo., last Wednesday (freezing drizzle was reported at the time), NTSB Chairwoman Ellen Engleman Connors was more cryptic Thursday. "There were some, shall we say, interesting characteristics" revealed by radar data, she said, but refused to elaborate. Frank Hilldrup, the chief NTSB investigator for the crash, said radar showed the Cessna dropping more than 1,000 feet in the 45 seconds before the crash (interesting to us, but we can't speak for Connors). Two witnesses reported hearing a series of loud pops just before the crash, leading some to speculate that the aircraft may have suffered an engine compressor stall (which can be caused by ice, among other things). The aircraft, owned by Circuit City, was carrying four of its employees and four others from Richmond, Va., to Santa Ana, Calif., and was being followed by a similar Circuit City aircraft that flew through light to moderate ice before landing safely about 12 minutes after the crash. The Denver Post drew comparisons between the Pueblo crash and the only other fatal U.S. accident involving a 560, which occurred more than nine years ago in Wisconsin. Two pilots, the only people aboard, died when the plane didn't make the runway at Eagle River, Wis., on Dec. 30, 1995. According to the NTSB report , that aircraft had collected about an eighth of an inch of rime ice on the left wing and vertical stabilizer and both engines contained a small area of ice beneath the final turbine wheel. Icing was listed as a contributing factor in that crash.