**There’s no need to book in advance for a normal taxi journey.** Prague Airport says its official **Uber Airport** cars are available 24 hours a day outside both terminals, including Sunday around 23:00. A short wait is still possible; availability doesn’t guarantee immediate departure. [Prague Airport taxi information](https://www.prg.aero/en/taxi)

For your dad, I’d suggest this:

1. Collect his luggage and clear customs.
2. Order **Uber Airport** through the Uber app or a self-service kiosk in Terminal 1. The kiosk works without an Uber account and takes card payment.
3. Take the six-digit PIN provided with the booking to the designated pickup area directly outside arrivals and give it to the driver.

The staffed taxi counters close at **21:00**, so at his arrival time he should use the app or kiosk. Cars require a booking and PIN before boarding, even though they are waiting outside. [Airport booking instructions](https://www.prg.aero/en/taxi)

Calling AAA once he has his luggage is also reasonable, but I can’t verify how quickly they would arrive tonight. Given your concern about waiting, I’d use the airport’s official service. Allow some flexibility on timing: a 22:40 landing may mean he reaches arrivals after 23:00.