Reader Graham Hibbard feels hemmed in by iCal’s 12-hour nature. He writes:
I am using 10.5 with iCal, and everywhere else on my MacBook seems to able to handle the 24-hour clock except iCal. I notice that any iCal events will only give me an AM/PM option. Any fix for this?
There is. Within System Preferences open the International system preference and click the Formats tab. In the Times portion of the window click the Customize button.
In the sheet that appears you’ll see the time in 12-hour format. Click on the hour and from the pop-up menu choose 1–24 to select the 24-hour format. To prevent AM and PM from showing you can either delete the contents of the Before Noon and After Noon fields or, in the field where the time is displayed, select AM or PM and press the Mac’s Delete key.
When you have things configured to your satisfaction, click OK to dismiss the sheet. If iCal is running, quit the application. When you next launch it you’ll see your events displayed in the 24-hour format. Should you wish to return to the U.S. default 12-hour format, just open the International system preference again, click the Formats tab, and from the Region pop-up menu choose United States.