A ‘No-show’ is when you: wish to cancel but don’t tell us before your rental is due to start, or fail to pick the car up at the arranged time and date, or fail to provide the documentation that’s required to pick the car up, or fail to provide a credit card in the main driver’s name with enough available funds on it for applicable payments at pick-up(such as deposit).

First of all, don't forget to cancel your booking if you've cancelled your car rental plan, so that you won't be considered as No show.
When you're going to be late for your pick-up due to flight delay or such occasions, contact the car rental supplier or contact us to reserve the car for you. Or else the car rental company will consider you as no show.