Some airports like LCY, a flex take off is allowed by the ops manual, but I would never consider it in the 146 as the time to recognise and act on a subtle failure is too short, and there are a great many obstacles on the climbout to the west. The occupants of Canary Wharf must be worried enough normally, but to see an aircraft staggering towards them at mid tower level would give them the s---s. The captain must make the descision regardless of the bean counters. Are you familiar with the 146, Killer shark?