I worked on United's computer systems for a year (never that one though), and so I get nervous when I see a headline like that. True story: one of their systems still runs on a mainframe that has 9 bits in a byte!
One of my friends used to intern for a very large company that maintained software for flight control towers. His entire summer was spent writing bash tests for these old Fortran apps that kept planes from running into each other. Most of the mainframes still had tape.
That's the code that keeps track of our planes.
Was the 9th bit special? Or just a standard bit in the byte?
If I'm not mistaken, some old consoles used a 9-bit RGB encoding, so this could theoretically help there. Minecraft also uses a 9-bit system for Redstone, afaik.
36 bits got us the 6-bit character (10 digits, 26 letters, and punctuation) with six characters in a word. Because of that, some OSes had six-character file names.
If you want to get upper- and lowercase, you need more than 6 bits. 9 is the smallest divisor larger than 6 of 36, so nine-bit characters made sense.
On such systems, file names could still use 6-bit characters, while applications used 9-bit ones. Also, some instructions could work on words, half words, quarter words, or sixth words.