Another interesting thing is that the attendants who casketed JFK in Dallas put him in a clear plastic mattress cover as the ER did not have body bags, and he was loaded in a standard military style shipping casket. When he arrived at Andrews, then sent via ambulance to Bethesda Navy Hospital, the attendants said he was in a zippered body bag in a bronze ceremonial burial casket.

That means the casket transfer and bod bag insertion had to have been done on board Air Force One. Why?