If you would like to enforce that users have checkouts before scheduling an aircraft or boat, you will need to do the following:
1. For each aircraft/boat, go to the edit page for that resource. Check the check box labeled 'Requires checkout' and be sure to save by clicking OK. The check box is highlighted in the image below.
2. For each user, go to the Pilot/Personal page of that user's account, and add any checkouts that they have completed. The checkouts can be specified by individual aircraft or by model. See grid highlighted in red below.
3. This option can be turned on in the Group Options page and is labeled 'Enforce checkouts by model'.