I did, once, many years ago. It will fit in the overhead compartments. But you couldn't pack your stirrups with the saddle --- I'm sure that would set off flags because they are heavy enough, and on stirrup leathers, and could be swung at someone as a weapon.
There have been many threads on this topic, and most of them have lots of good info. Roll the flaps a bit and it should fit in the overhead or under the seat. Take the stirrups off and put them and your spurs in a checked bag. Try to get on first so you can get overhead space. Expect it to be counted as your one large carry on bag; the only other thing you will be able to carry on with you will be your personal item (purse, small briefcase, etc.) Should be no problem though. Good luck!
I took my Western sidesaddle with me to the Kentucky Horse Park and the baggage clerk told me they would prefer if I would put it in a box to protect it. I do not know about the English in the Carry On. You would most likely have to put the stirrups & girth in your baggage. You might want to call your airline and ask them.
I know they are getting more strict on what size an item is for Carry On luggage.
It is super easy to carry your saddle as a carry on and you do not have to remove your stirrups. My daughter flies all over the country and always carries her saddle. She has never had a problem. Checked bags have a weight limit of 50 lbs before you are charged a hefty fee, so you might not want to put your stirrups in your checked bag if you have other heavy riding gear in there. My daughter mostly flies Southwest, but on occasion has flown JetBlue, American and United. Southwest lets you have two checked bags for free.
It was awful. I was escorted off the plane, two kids aged 2 and 8 left on. TSA guy telling me I can't have a reptile. Reptile? WTH 4th grade science class did he go to? Gate agent looking repulsed. I wanted to get the kids off the plane and throw a fit, but I'm so scared of getting on the No Fly list. Daughter was hysterical. Flight attendant said she would watch while I got off the plane. Came back and she was nowhere to be found. The TSA guy couldn't tell me what I could do with them. Gate agents equally stupid. I said 'you dragged me off the flight you better effing tell me what you want me do with these crustaceans". Gate agent finally took the carrier. I'm sure they just threw them away. To blazes with the idiots at Southwest and TSA
I know this thread is old, but I'm bumping it partly in thanks for everyone else's info. This thread eased my mind last night as I was approaching flight time.
I'm flying today (Christmas) on a Canadian Regional Jet. That's one of those small little things with teeny overhead compartments where everybody's rolling bag gets gate checked.
I'm sitting at the gate now, and my gate agent was really nice; as I walked up he said "Ooh I know what that is!" He grew up on a QH farm so he gets it, and he said if I was willing to fold the flaps it should fit just fine under the seat. It's in a nylon carry bag with faux fur lining. I didn't bring the stirrups.
So there it is for folks who are paranoid about taking their saddle on a smaller plane.