It’s not the way airlines currently do it.

The fastest way: Jason Steffen, an astrophysicist at Northwestern University has determined the optimal method of boarding a single-aisle passenger jet is as follows:

• Board the window seats on one side, but every-other row,
• Then the window seats on the other side, every-other row,
• Do the same for middle seats
• Then aisle
• Then repeat for the above for the rows that are empty.

According to Wired, “Steffen’s simulations found that boarding is most efficient when you give them two rows of space to stash their stuff. On a plane with 20 rows, that means having no more than 10 people boarding simultaneously (a 40-row plane can handle 20 people), filling every other row down one side of the plane — 1A, 3A, 5A and so on — then the other. Try to get any more than that aboard and things start slowing down quickly.” 

The Steffen method allows passengers room to place bags overhead and to move comfortably into their seats without interference. 

Most airlines board economy back to front. Dr. Steffen says that this doesn’t really provide an advantage over boarding front to back:  “People standing in the aisle of the airplane are just standing in line. Loading back to front just moves the line inside the plane, but is not significantly faster than loading from the front to the back.”

The second fastest boarding method according to Dr. Steffen is random. 

Mythbusters tested various methods of boarding a plane and found that the free-for-all method used by Southwest Airlines boarded the fastest, followed by random boarding order with assigned seats. Boarding back to front or by window, middle and then aisle, were much slower than the free-for-all or random boarding methods. Mythbusters did not test the Steffen optimal method.