Appointments are made in local time. Store them in local time.
You may just be illustrating a particular use case, but it is more ambiguous in the general case. For example if you have arranged a meeting with someone in another timezone then maintaing the local timezone could lead to a misalignment for one of the participants.
This is ok. When future local user time offset is unpredictable, pinning meeting time to a certain location is a good strategy. If at some point meeting shifts for some user, well-designed calendar app could warn them and let reschedule.
It still works better than pure UTC because it is predictable for at least some of the users.
Comments
You may just be illustrating a particular use case, but it is more ambiguous in the general case. For example if you have arranged a meeting with someone in another timezone then maintaing the local timezone could lead to a misalignment for one of the participants.
This is ok. When future local user time offset is unpredictable, pinning meeting time to a certain location is a good strategy. If at some point meeting shifts for some user, well-designed calendar app could warn them and let reschedule. It still works better than pure UTC because it is predictable for at least some of the users.