No official death certificate needed! You need to have the cremains in a sealed container. We brought my mother in law's with us on Allegiant Air in May. They were still in the black plastic box from the crematory and we went to the funeral home to make sure we had what was needed for TSA. They took Scotch tape and sealed the box, gave us a preliminary death certificate, the cremation authorization, and a letter from the funeral home stating that we would be traveling with her remains in a plastic bag. We told TSA at check in and they took the bag with her cremains to wipe the container with the explosive residue while we watched. They never looked at the paperwork!!
I do believe you would need a death certificate, certificate of cremation and a certificate from the funeral home that the urn contains that ashes of the deceased. When in doubt always call your local TSA office and airline
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