The Bombardier Challenger CL-600, which crashed on January 4 killing all five onboard, may have suffered from icing. A special bulletin by the UK Air Accidents Investigation Branch states: “During the morning [of takeoff], witnesses stated that they had seen frost or ice on the wing surfaces of N90AG prior

to departure.”

It went on to say that other aircraft, which had been parked overnight, were de-iced during the morning, with associated reports of moderate to severe ice or frost accumulations. It is reported that neither crew member requested de-icing, so N90AG was not de-iced prior to departure.

The CVR indicated that the crew members were operating normally with no apparent time pressure. The left seat pilot was handling. There were no audio warnings activated until shortly after take-off when the automatic voice ‘bank angle’ sounded; this occurred within two seconds of the end of the recording. From the CVR, there was no indication that the aircraft’s wing and cowl anti-ice systems were selected ‘on’ prior to take-off.