Originally Posted by YVR Cockroach

57. (1998) From your home in Scottsdale, Arizona you need to travel to Montreal, Quebec for a symposium on light rail options and operations hosted by Bombardier, one of the world's largest companies in the rail vehicle and equipment manufacturing and servicing industry. With plenty of time available to you before the symposium, you decide to have a bit of fun with your flights out to Montreal. To wit, you’ve found a combination of flights that will allow you to.

• Fly between PHX and YMX aboard a 727, 737 and 747 in that order
• Both the 727 and 737 flights will be in all-economy configurations with only the 747 offering premium class seating
• The 727 and 737 flights are not variant specific

It’s worth noting that given the departure point of the 747 into YMX, one and only one routing meets the specifications outlined above, especially given the use of single class configured aircraft. BTW, you will overnight at the final connection point though this shouldn’t have any bearing on the parameters described above. Good luck, men!
The first segment has been identified as ATA PHX-MDW on a 727. The 747 into YMX comes out of Pittsburgh. So, all we need is the 737 operator between MDW and PIT. It wasn't Midway...

One more kick at #57 ~ USAir's MetroJet MDW-PIT

So I went and checked - US Air only operated out of O'Hare on its flights to Pittsburgh. In fact, only one airline operated out of Midway to Pittsburgh, and that's the airline we're looking for. And now for those wonderful words you know I do so love to utter:

Please, guess again!