IMHO the massive safe expansion of LoCO's we've seen over the past 10 years could not have happened with the equipment of the 70's & 80's. However, and here is my curiosity, SWA DID expand rapidly and used B732 and basic B733 with a down-graded instrument display. It seemed successful. Perhaps those on the inside could enlighten us. But, does anyone believe RYR could have expanded from 25 - 300 a/c over 45 bases in 12 years if they still used B732's?
No idea if the uniqueness of this criterion described in a book on SWA first published almost twenty years ago still applies and/or can be a potential explanation (apart from the
arguably quite unique management style of SWA with collaborative rather than adversarial employee relations):
"Southwest Airlines is the only company in the airline industry that requires a pilot to have a 737-Type Rating before he or she is considered for hire. This rating, given by the Federal Aviation Administration, essentially says a pilot is qualified to be the captain of a Boeing 737. This means that all first officers are qualified to fly as captains."
(Freiberg, K. & Freiberg, J. (1996): NUTS! Southwest Airlines' Crazy Recipe for Business and Personal Success. Austin, Texas: Bard Press, p. 98f.)