Has anyone traveled with an 8 to 9 wk old lab pup on airplane, crate dimension requirements are 23 long, 13 width and 9 in tall? length and width requirements look ok but height may be an issue

23 inches is way too long. That's the length of a rollerboard suitcase that fits ABOVE the seats. Your pup will need to go in a Sherpa or similar soft-sided carrier to fit under the seat in front of you.

The Pet Travel Store carries the Sherpa Pet carrier and other airline travel products.

is there a weight limit on pets for in-flight travel, 9 wk old pup may be around 18#'s

There is a weight limit for the puppy plus the carrier to ride in the cabin. Check with the airline...it may be a total of 20#...