Q: iTunes won't backup my iPad Air.

Hi chugalong,

Welcome to the Apple Support Communities!

I understand that your are unable to back up your iPad to your computer because you keep getting an alert that you iPad has disconnected. This alert typically is a result of the USB port, Lightning cable, or Lightning port on your iPad. To troubleshoot this issue, please read over and work through the steps provided in the attached article.

iTunes: Resolve USB-related alerts - Apple Support

You also mentioned not being able to back up your iPad to the iCloud. You do not need iTunes or a computer to back up to the iCloud. Please use the information in the next attached article as a reference for how to back up your device to the iCloud. 

Back up and restore your iPhone, iPad, or iPod touch using iCloud or iTunes - Apple Support

Cheers,

Joe