I have a flight booked for Saturday that my parent booked for me, insisting that I will be able to get into Canada. I have my expired Canadian passport, and my original birth certificate, also I have my permanent resident card issued by America. I am wondering if I will even be allowed on a flight, Alaska Airlines, with an expired passport. I was told that I am Canadian so they can't not let me in, I'm just unsure if they will even let me on a flight, this would be a lot easier and hassle free if I was driving across the border but that is not the case.
TIMATIC thinks your Canadian passport cannot admit you because it's expired. "Passports and other documents accepted for entry issued to nationals of Canada must be valid on arrival." Whether you would actually be turned away is another matter, but a cautious airline would be unwise to board you in violation of the clear instruction there.
However, TIMATIC goes on to say under the 'Passport exemptions' category, that you should be admitted with your Green Card: "Permanent residents of USA holding Permanent Resident/Resident Alien Card (Form I-551), arriving from USA or St. Pierre and Miquelon."
Therefore in my view you are in principle entitled to travel and enter Canada merely with your Green Card (although certainly bring along the Canadian passport as well). If you face trouble, ask for the agent in question to confirm the information in TIMATIC, under the passport exemptions category.
Information as of 10JUL15 / 1416 UTC National Canada (CA) /Residence USA (US) Embarkation USA (US) /Destination Canada (CA) Canada (CA) Passport required. - Passports and other documents accepted for entry issued to nationals of Canada must be valid on arrival. - Warning: if departing from the USA (regardless of any destination passport exemptions), a valid passport and/or is required by the US immigration authorities. Passport Exemptions: - Holders of a valid on arrival NEXUS Card issued to nationals of Canada, if residing in USA. - Permanent residents of USA holding Permanent Resident/Resident Alien Card (Form I-551), arriving from USA or St. Pierre and Miquelon. VISA NOT REQUIRED. Minors: - If a travel document issued by Canada to minors under 16 years of age displays "Signature Not Required/non requise" - Parent(s) traveling with a child under 18 years are strongly Canada (CA) Vaccinations not required. Warning: - Any visitor irrespective of length of intended stay in Canada may be referred for medical examination if deemed necessary.