air travel to Canada on expired us passport ?

no, you don't need the passport on the trip to canada. If you are American ciziten and you can going to Canada without use the passport.

What about it. You don't need a passport to get to Canada if you are American.

Actually, you do need a passport. You are still crossing international borders and yes some airlines will accept a driver's license, but reading the news, it seems that more and more passports will be required. If I were you, I would renew the passport before travelling.

i used my expired passport and my birth cirtificate to get into canada last week but i think after this year you will need to have a valied passport to go to all countries other than the us so before that you should be fine

PASSPORT FOR CANADA REQUIERED EXCEPT FOR:
...
VISITORS:
1. THE FOLLOWING CATEGORIES, PROVIDED THEY CAN PROVE THEIR STATUS:
A. NATIONALS OF U.S.A., WHO ARE RECOMMENDED TO HOLD PROOF OF CITIZENSHIP, SUCH AS:
- PASSPORT (MAY BE EXPIRED); OR
- U.S. BIRTH CERTIFICATE; OR
- U.S. CITIZENSHIP OR NATURALIZATION PAPERS.
DOCUMENTS THAT DO NOT INCORPORATE A PHOTOGRAPH SHOULD BE ACCOMPANIED BY SUPPORTING GOVERNMENT ISSUED PHOTO IDENTIFICATION.

B. LEGAL PERMANENT RESIDENTS OF THE U.S.A. SEEKING ENTRY TO CANADA FROM THE U.S.A.