Why do the flight attendants insist that all window blinds be up for take-off?

The most critical phases of a flight are the take-off and the landing. In the most unlikely event of a situation that requires an emergency evacuation, it is important that crew and passengers are able to have a clear view of the outside conditions in case of obstructions. For example, before exits are opened, staff must check for fire or other obstacles that may present potential hazards during the evacuation.