To protect a passenger is to preemptively book them on an alternative flight without canceling their original ticket. Airline agents use this tactic during severe weather, mechanical delays, or tight connections to ensure the passenger has a guaranteed seat if the primary itinerary falls through. Once the outcome of the original flight is known, the unused reservation is dropped.
Weather in Chicago is getting worse, so I went ahead and protected you on the 6 AM flight tomorrow just in case.
Related terms
Standby
A travel status where a passenger waits at the gate for an unassigned seat to open up.
Go-show
A passenger who arrives at the airport hoping to fly on an earlier flight than the one they booked.
Ticket designator
An alphanumeric code on an airline ticket indicating a specific fare type or discount.