Project ID

CDM – rigorous standard set up by the United Nations. Uses CER certificates.

Gold Standard – robust standard particularly focused on benefits for the local community, uses either CER or VER certificates.

VERRA – formerly VCS, wide variety of projects covered by VER certificates.

ACR – American Carbon Registry – various domestic projects.

No – Not covered by any of the above. Other standards may apply but often lack the rigour of the main international standards. As an alternative you could consider carbon offsets for your flight that use high quality international project standards and are QAS-certified. (link to QAS-approved page)