The baptisms with water cannons that we call “salutes” are made to mark some unprecedented moments, for example: when the captain is going to make the last flight before retiring, the first flight of a new model to an airport, when something is out of the ordinary or illustrious to celebrate or pay honor. Generally, the person who initiates the conversation to request the salute is the airline, as they need to agree with the airport and the fire department. Although it is not documented when this type of greeting was first used on an airplane, the tradition certainly comes from the Navy. By the way, aviation inherited many things from the merchant Navy.
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