Airline carry on size is 22 x 14 x 9. Some airlines allow slight variations of this size, but this should work for all US airlines.
An over-booked flight may warrant a carry-on baggage check due to limited overhead luggage space. If it doesn't fit in their check frame, it will need to be gate checked-in. I've never run into any problems with over-sized bags when flying First, but have had issues with over-booked economy and smaller commuter airlines. My LowePro CompuTrekker AW backpack barely fit depth when stuffed with my old 13" laptop and Cameras. I was surprised they asked to test it. (It was bulging quite a bit) I made sure my ThinkTank roller was International carry on friendly.
All mainstream DJI hard cases except the 1510, 935, or IM2500 are larger than regulation standard. Most times, you may not run into problems, but you take your chances.
I was about to pull the trigger on the Nanuk 935 when another poster confirmed the P2V+ indeed had a taller landing gear.
Again, looking for someone with a Nanuk 935 or Pelican 1510 for firsthand knowledge. If it's larger than, 22x14x9, no thanks. May only have a thin piece of cloth or foam at the motors and skids, but if it fits without compressing or binding, it may be worth a try.