Finally, I gave up the try, replace Ipad Air with Ipad Pro now. no crash till now with 2 rides already.
Which MacBook Pro?
While it may not be a CPU issue, it could very well be a GPU issue.
My 2015 MacBook Pro has not been affected by this issue. Hence, my question regarding your MacBook Pro specs.
That’s an old one. El Capitan (10.11) is already 4yrs old. I doubt w/that graphics card/chip it is Mojave (10.14)compatible. However, OS X can definitely be upgraded to at least Sierra (10.12) if not High Sierra (10.13). I recommend you upgrade OS X. I cannot promise it will solve your problem, but there is a very good chance that it will.
Of course I know that you know how old your laptop is 
That statement was more for myself than to inform you. Perhaps you cannot upgrade OS X because it will break some other app or something. If that is the case, then you’re probably at a dead end w/that laptop regarding Zwift unless a new Zwift update changes something.
Yes, it’s odd that it works in all worlds but Watopia. Chances are very high that it has to do with the recent Watopia expansion. Related, some users were unable to even start Zwift after the expansion. However, after ugprading OS X from El Capitan , Zwift was back to normal. In your case, Zwift starts and runs well unless it’s Watopia. Perhaps, it’s the graphics/video driver. Perhaps, it’s some other dependency. Either way, because we use OS X, we have to upgrade the entire OS in order to get a new video driver, etc… Unlike Windows where one can download and upgrade only the video driver.
As for the older iPhones, iPads, etc., Zwift acknowledged there was a problem and are working on a fix. However, that was 27d ago 
Maybe when they fix that, your MacBook issues will be fixed as well.
Do you know if the Garmin Ant (USB2) is compatible w the iPad Air? I bought the usb lighting adapter but didt work! Any advice will be more than welcome.
Dennis
The USB Lightning adapter only works for specific USB devices. It won’t work with ANT+ adapters. You’ll need a special ANT+ adapter for the 30-pin port then convert that to Lightning (expensive and unsupported), or get one of those special ANT+ to Bluetooth converters such as CABLE or Viii.