It’s not every day that an airline passenger accidentally locks pilots out of the cockpit… fortunately it happened while on the ground.Passenger accidentally locks Southwest cockpit doorHow flight deck doors are ordinarily openedBottom linePassenger accidentally locks Southwest cockpit doorOn Wednesday, May 24, 2023, a Southwest Airlines flight from Sacramento (SMF) to San Diego (SAN) had a slight delay because the pilots got locked out of the cockpit.How could this happen? Well, while the aircraft was at the gate, a passenger reportedly opened the forward lavatory door, and inadvertently pushed the cockpit door of the Boeing 737 closed. I can totally see how this can happen, since often the lavatory door and cockpit door are “hooked” together during the boarding process, just so they don’t keep slamming into one another.When the cockpit door was inadvertently closed, the pilots hadn’t yet boarded, so there was no one in the cockpit. It’s not unusual for passenger boarding to start before the pilots get on the aircraft, especially on Southwest, given that the airline often operates “direct” flights, which have a stop, and passengers don’t have to deplane.The pilots ended up gaining access to the cockpit by having some stairs pulled up to the cockpit window. The cockpit window was then opened, and the pilot climbed in that way. The flight only ended up being delayed by eight minutes.How flight deck doors are ordinarily openedUnderstandably, many people are puzzled by how aircraft engines are started, how cockpit doors are opened, etc. No, commercial aircraft don’t have keys that you open the cockpit door with, or that you use to start the engines. Rather there are procedures in place, and they just involve physical access to the aircraft and knowledge, and not any keys.Below you can see an interesting training module for how to open the cockpit door of the Boeing 737. As you can see, there are different settings depending on the situation.Bottom lineIt’s not every day you hear of a passenger locking pilots out of the cockpit, but that’s exactly what happened on a Southwest flight earlier this week. Passengers had boarded before the pilots, and someone tried to use the forward lavatory, but accidentally closed the cockpit door in the process.This meant the cockpit was locked from the outside, so the crew had to get creative with cockpit access. Stairs were pulled up to the jet, and then the pilot climbed into the cockpit.What do you make of this Southwest 737 cockpit incident?