airplane travel

Question
I was told by the airline representative.  I didn't know that a crate would be allowed in the cabin, they told me it must be a carry on and fit under the front seat...and those were the dimensions I was told had to fit under the seat.  Thank you for your quick response, when you travel with your dog, do you put him in cargo?  -------------------------
Followup To
Question -
I have a chihuahua-dashaund-terrier dog which is about 13-15 lbs.  I want to take him with me on a plane trip, but was told dog must be under 20 lbs and carry on dimensions must be  20'long, 13'wide, 9'height, dog must be able to stand up and turn around to take as carry-on with me and be able to put him under the front seat, I can't find carry on with those dimensions, and I know the dog's head is about 11 inches in height, so I don't think he would fit under front seat,  but I was told that he can go in cargo area but some people tell me it's too traumatic for the dog, that I must have him tranquilized and that he can die from the heat, etc. Is it safe to put him in cargo?  What has you're experience been? Thank you...
Answer -
Who says the dog must be able to stand up in the crate?  Dogs can be comfortable in a crate too small to stand up in.  They must have room to stretch out in.  On the other hand, you may have trouble finding such a low, flat crate.  Perhaps you need to talk to the airline again.  I am trying to remember if even the smallest crates or carriers are only 9'' high.  

Your dog will be much better off even in a cramped crate in the cabin with you than the cargo hold.  I have never flown with a small dog, but I know people are allowed to have them in crates in the cabin.  

Answer
Some people ae privileged characters and can have their dogs loose in the cabin because of the service dog tag.  I have seen other people with little dog and cat in carriers.  The airlines have gotten tougher on carry ons recently.  it may be that it is no longer possible.  It still could be worth rechecking.  If you get a better answer, you may want to document it.  You might also try to find out what their website says.  There may be a pet exception to the regular rule you were given.