When things go bad
Plan for the things you know can happen. Weather emergencies, hazmat spills, and fires come to mind. Rick Rescorla's plan for what Morgan Stanley workers should do if the World Trade Center was attacked, is one reason why that firm only lost six people out of almost three thousand on September 11, 2001.
I can't recall now, but I think there are studies that show people will be lulled into not acting when a group of people is around (who are also not taking action). So something is introduced that if they were alone they would react (say leave the trade center, or investigate a seemingly risky piece of data). But if there is a group people become more passive - thinking the non-action by others means they are over-reacting. So they then don't react (thus re-inforcing everyone else decision not to act).Include some thinking about how you will know what you're facing. While the Port Authority officials were broadcasting "stay put" messages, Rick decided that an attack was happening. He activated his plan, marching his company employees down the stairs, two by two.
This is one of those times leadership really matters: someone not afraid to take action and potentially criticized for going against the consensus group decision to not act.
If immediately upon suggesting decisive action, people jump to support the idea it is likely they all would have done so alone but were intimidated by the non-acting group. Either that or they respect the leader and decide to support them while not sure it is really needed.
Related: Leadership is the act of making others effective in achieving an aim - Leadership Leverage Points - quotes on leadership