Looks like AY has read FT and is doing what [MENTION=389972]intuition[/MENTION] suggested (albeit for widebodies).
https://www.flyertalk.com/forum/30797358-post3270.html
I'd give a Burnsian 'Excellent' for this:
Door 1 -> F
Door 2 -> J
Y do tarmac boarding via door 4