Captains can send a pre-approval to let you know they are available for the date and trip you asked about.
If a captain sends you a pre-approval, it means you can book the trip without waiting for him to approve your booking request. If you receive a pre-approval, you have 24 hours to click Book Now and complete the booking process to confirm your reservation.
If the offer expires, you still have the option to request the trip, but you will need to wait for the captain to approve your request.
Note: Always check booking details and the price breakdown before submitting a request.