Improper de-icing procedures led to an accident that substantially damaged a Flexjet Challenger 300 last winter at Chicago Executive Airport, according to the NTSB. The Safety Board concluded that the operator of the de-icing vehicle did not adhere to company procedures and did not maintain clearance between the vehicle’s boom and the airplane during the de-icing operation. An airport maintenance person told investigators that after the twinjet taxied to a run-up pad he saw the Signature de-ice truck hit the horizontal stabilizer on the right-hand side, and saw the twinjet’s nose move forward, then down. According to Signature’s de-icing training guidebook, the driver of the de-icing vehicle driver should “always know where the boom and bucket are located.”