System requirements: Your Macbook Air must run OS X Yosemite or later and your iPad Air 2 must run on iOS 8 or later.
- Devices must be close to each other.
- Each device must be logged into iCloud with the same Apple ID.
- Each device must have both Bluetooth and Wi-fi on (but not connected, necessarily).
- Each device must have Handoff on:
- Mac: (Apple Menu) > System preferences -> General -> Allow Handoff.
- iPad: Settings > General > Handoff
- The app you are using must support Handoff (Apple's native apps like Mail, Maps, Safari, Reminders, Calendars, Contacts, Pages, Numbers, Keynote does), but not all third-party apps does.
If you're still experiencing trouble, it might be worth doing a reboot of your Mac and iPad. Worst case, you would need to reinstall macOS (OS X) and/or iOS on your devices. If it still doesn't work, it might be something wrong with the Bluetooth and/or the Wi-fi radios in either device. Isolate by testing each device with another device (if possible), go into an Apple Store to get help or by contacting Apple (getsupport.apple.com).
Hope this helps,