I lost my ipad in the plane,how can you help me!

Here is Apple’s advice for lost or stolen devices:

If your iPhone, iPad or iPod touch is lost or stolen – Apple Support

Use the Find My app to locate a lost or stolen device – Apple Support

If the Find My iPad feature was enabled prior to it being “misplaced”, then if active and with a network connection, you would stand a good chance of locating it. 

However, if the feature was not activated prior to being misplaced - or the iPad has been inactive for more than 24 hours, the last known location will not be available - and the opportunity to use technical means to recover the iPad have been lost.

There you go:

https://support.apple.com/en-us/HT201472

Did you have 'find my' enabled?

If not, not much you can do except report it to the airline and/or airport and hope someone is honest.