In an earlier post, I advised you to choose a middle seat, since they generally have the most room to stow a dog in a carrier. Not long afterwards, I encountered a middle seat under which I really couldn’t stow Chloe because a significant portion of the space was occupied by a box for electronics. Happily, this wasn’t a plane with one of those railings that cuts off a big chunk of the storage space under the aisle seat, so I stowed her under my husband’s feet.

It raised the point, though, that under-seat space varies by plane, and  therefore choosing a seat for your flight with an in-cabin pet is more complicated than I first thought. I’ve started making notes about which seats, on which planes, best accommodate a pet in a carrier. This post is the first in the series. Keep in mind that most domestic and international airlines have rules about the maximum size of in-cabin pet carriers they allow on board (see Dog Jaunt’s handy charts under the “Taking your pet on a plane” tab above).

Southwest 737 (-700 series)

Southwest has published its under-seat dimensions, and I applaud them for doing so, but I don’t think their measurements tell the whole story. We just traveled on a couple of Southwest 737 (-700 series) planes, and here’s what I learned.

The plane has only one class of seats, so no need to worry about the dimensions under first/business class seats versus coach seats. There’s only one bulkhead, in front of the first row. It has no cut-out in the bottom, so you won’t be able to travel there, nor will you be able to travel in the exit row seats.

The middle seat was the best choice for a pet carrier, being a full 19″ wide. The window seat was slightly narrower — just shy of 18″ wide. The aisle seat had a railing that made it very narrow indeed — between 14″-15″ wide. [9/7/10 We traveled today on a Southwest flight and I finally remembered to measure the under-seat height, which is 11 inches. Why Southwest tells you it’s 8.25 inches is a mystery to me.] [12/4/10 But see a reader’s comment, below, reporting that the under-seat height on his flight was, in fact, 8.25 inches. We’re scheduled to fly on five more Southwest flights in the coming month, so I’ll measure more under-seat spaces and report back.] As you can see from the crossed-out text, the under-seat height measurement wasn’t straightforward, but I think I have it sorted out now. Put briefly, a hard plastic life vest container reduces the under-seat height to 9-9.5 inches — but the container is set well back under the seat, and doesn’t interfere with the large SturdiBag we use, though it might well pose a problem for a large, rectangular carrier with inflexible edges.

Comparing my measurements to Southwest’s published measurements, you’ll see that the window seat on our planes was wider than advertised. Perhaps Southwest’s 737s in other series (-300 and -500) have narrower window seats, and the airline chose to lump all the series together in its calculations.

This discussion of widths may seem pointless to you since the length measurement provided by Southwest (what I’d call “depth” — that is, measuring front to back under the seat) is 19″ for all of its seats, and surely that’s generous enough to cover most carriers. In my experience, though, a carrier inserted front-to-back under the seat pokes a few inches out into your legroom area, and flight attendants hate that.

You may get away with it — my neighbor on the last flight had a Bichon Frise in a huge Sherpa carrier under her seat, and did a remarkable job of concealing the fact that she had no leg room left by crossing her legs and draping a sweater casually over her knees — but be prepared for objections from flight attendants. To avoid them, choose a seat that can accommodate your carrier side-to-side — for most of us, that means the middle seat, or, if you’re lucky, the window seat.