This was how the original Eastern Air shuttle service worked. They ran flights between Washington, DC, Boston, and New York, scheduled to depart every hour on t

This was how the original Eastern Air shuttle service worked. They ran flights between Washington, DC, Boston, and New York, scheduled to depart every hour on the hour. No reservations, just show up and walk onto the plane and you could pay the fare (roughly $12 in early-1960s dollars) on board. And if the hourly plane filled up and more people were still waiting to board, they'd roll out another plane. The hourly flights still exist (now run by American, which inherited the service from US Airways in the merger, which bought the service from Donald Trump's creditors after he defaulted on the loans he used to buy the service from Eastern when Eastern got into financial trouble), though of course now you have to buy a ticket before you go through security.