This may not be the proper forum but....I recently left my I-Pad on an airplane after flight between Zurich and Frankfort. Someone told me that it may be possible to trace it. Is that true? and if so what info is required?

Were you using iCloud? Did you have Find My iPhone turned on in the iCloud settings?

http://support.apple.com/kb/PH2698

Yes in the iCloud settings. It is actually called Find My iPad on the iPad

Then there is no way to track it.

Moral: read the manual.

Apple (and no one else) can not assist (with serial number or iCloud) in finding a lost or stolen iPad.

Report to police along with serial number. Change all your passwords.

These links may be helpful.

How to Track and Report Stolen iPad

http://www.ipadastic.com/tutorials/how-to-track-and-report-stolen-ipad

Reporting a lost or stolen Apple product

http://support.apple.com/kb/ht2526

What to do if your iOS device is lost or stolen

http://support.apple.com/kb/HT5668

iCloud: Locate your device on a map

http://support.apple.com/kb/PH2698

Report Stolen iPad Tips and iPad Theft Prevention

http://www.stolen-property.com/report-stolen-ipad.php

How to recover a lost or stolen iPad

http://ipadhelp.com/ipad-help/how-to-recover-a-lost-or-stolen-ipad/

How to Find a Stolen iPad

http://www.ehow.com/how_7586429_stolen-ipad.html

What NOT to do if your iPhone or iPad is lost or stolen

http://www.tomahaiku.com/what-not-to-do-if-your-iphone-or-ipad-lost-or-stolen/

Apple Product Lost or Stolen

http://sites.google.com/site/appleclubfhs/support/advice-and-articles/lost-or-st olen

Oops! iForgot My New iPad On the Plane; Now What?

http://online.wsj.com/article/SB10001424052702303459004577362194012634000.html

If you don't know your lost/stolen iPad's serial number, use the instructions below. The S/N is also on the iPad's box.

How to Find Your iPad Serial Number

http://www.ipadastic.com/tutorials/how-to-find-your-ipad-serial-number

iOS: How to find the serial number, IMEI, MEID, CDN, and ICCID number

http://support.apple.com/kb/HT4061

 Cheers, Tom 😉