Sentence examples for back up plan from inspiring English sources

"back up plan" is a correct and usable phrase in written English.
You can use it when describing a contingency plan or alternative course of action in case something goes wrong. For example: "I always have a back up plan in case my flight gets delayed." "Our team has a back up plan in case our main supplier cannot meet our demand." "It's always a good idea to have a back up plan when making important decisions."