I guess I'll end up risking it. Seems like my chances are good for getting it past, especially sleepy LAS. I am tempted to drive down to LAX, wheel this thing into Frontier and jam it in the sizer to confirm, even though it's an hour or so drive.

Based on the published dimensions 18" x 12.5" x 6.5" it should work. You can always take it to the airport and try it in the sizer.

I'm flying with my family & young kids. We will be checking a carseat (free) and probably one bag.

When I fly with family I usually use my Ebags Motherlode Convertible: http://www.flyertalk.com/forum/front...onal-item.html in backpack mode (without the waist strap). It's 22x14x9, but a backpack. Am I going to have any luck avoiding the carry on fee?

We aren't flying F9 for the return, so i'm juggling baggage requirements.

Also, I vaguely remember seeing food excluded from the personal item definition? If we buy food at the airport is that using up one of our personal items?

A year ago, I measured an UPPTÄCKA orange wheeled children's cabin bag at Ikea. It was slightly less than each of Frontier's dimensions for a personal item. I am 6 ft 1 in and the telescoping handle was just long enough. At the airport, I put it in the Frontier sizer at a gate when no Frontier people were around, and it fit in the sizer. No Frontier employee has given it a second glance.

Ikea sells various items of luggage under the UPPTÄCKA name.

I have read that Spirit's personal item allowance will be:
For Travel April 4, 2017 & Beyond: 18”14”x8”
so the bag should work on both airlines eventually.

Did the Protege Pilot Case, 18" bag fit? Has anyone been using this bag lately on Frontier?