Delta has many, many versions of this plane, but I believe we flew on this particular configuration (seat plan courtesy of SeatGuru), with the Delta Comfort+ seats starting at Row 18, cattywampus to the bathroom (an unusually pleasant one, with — how brilliant — rounded doors, giving you the pleasant illusion of having more space).

In recent years, I’ve shunned Delta. Their seat pitch had become ludicrously small for me, and crippling for my husband, so in a grand gesture, I spent all of our remaining Delta miles on First Class seats on some really short flight, and plighted my troth to United. But the years have rolled on, and Delta does have a direct flight from Seattle to New York, and they’ve added leg room back in — for a price, of course — with their Delta Comfort+ seats. (Buy them, I urge you. The extra room makes it possible to reach down and pat your dog, or give her ice cubes or water, or pull her carrier out a bit from under the seat in front of you.)

We were in Row 21, seats D and E. The window seat underseat space is trapezoidal, essentially, since it curves outwards and upwards with the plane’s side wall, but at ground level, it’s 18″ wide, 12″ high (in front — about 7″ from the front plane of the space, the hanging life vest box lowers the height to 11″), and the usual 17″ or so of depth. The aisle seat underseat space is 13.5″ wide (all the remaining measurements are the same). The middle seat underseat space is 17″ wide (all the remaining measurements are the same). Please note that the middle and window spaces are further altered by the presence of an electronics box about 2.5″ wide and 4″ tall. It’s on the left side of both spaces, and although it’s in the upper left corner, it does effectively narrow both areas. Under the window seat, it narrows the available space by about 3.5″, and under the middle seat, it narrows the available space by about 5″. The middle seat, moreover, has another plastic box in the upper right side of the space that projects inwards about 2.5″.

Chloe, tucked in under a Delta Comfort+ seat on a B757-200(75S) plane. Please note the boxes to the left and right of her carrier (the one on the left has a green light). The middle seat worked, but either of the other seats would have been better.

Not knowing anything about this particular plane, we took a chance on the middle seat. More often than not, a middle seat is a good choice for a traveler with a pet, but, it turns out, not this time. We managed it (yet again, the rounded and flexible top of Chloe’s large SturdiBag saved the day), but the window seat would have been best, and the aisle seat would have been my second choice.

This post is part of an ongoing series recording under-seat measurements of the various planes we fly on. 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).