Choice Plus” adds these extras to the Choice Essential items: 50 percent more AAdvantage miles, the ability to change the flight to another flight on the same day, the ability to stand by for another flight the same day and one premium beverage on board the flight. The cost is $88.

At the end of this sentence, you can see 'on board the flight' is this correct gramatically?
I guess 'on board during the flight' or 'on board of the flight' is correct.
Pls explian this.