Normalization of deviance is the gradual acceptance of substandard practices due to a lack of immediate consequences. In the fire department, this can lead to complacency in safety protocols and equipment maintenance, increasing the risk of serious incidents. Examples like the Boeing 737 Max crashes and the Titan submersible disaster highlight the dangers of ignoring safety issues and cutting corners until it's too late, emphasizing the need for firefighters to promptly address lapses to maintain high safety standards.