On nuclear-powered subs, there’s a brass bar in front of the control panel for the power plant. When status alarms begin to go off, the engineers are trained to grab the brass bar with both hands and hold on until they’ve looked at all the dials and indicators, and understand exactly what’s going on in the system. What this does is help them overcome the temptation to start “fixing” things, throwing switches and opening valves. These quick fixes confuse the automatic recovery systems, bury the original fault beneath an onslaught of new conditions, and may cause a real, major disasters. It’s more effective to remember to do something (“Grab the bar!“) than to remember not to do something (“Don’t touch that dial!“) So, grab the bar!
From Debugging by David J Agans