I will be traveling on United airlines and Lufthansa to Italy. If I use a 21" bag as my carry on, how large can my "personal item" (such as a handbag) be? I'd like to carry a partially filled day pack, but am worried that this would be considered a second carry on.
Your "personal item" can be a purse, a coat, a laptop, a backpack, whatever -- as long as it fits under the seat in front of you.
Per United's website: You may carry on one bag and one personal item such as a purse, briefcase, or laptop computer. A carry-on bag must fit under your seat or in the overhead bin. Carry-on bag dimensions should not be more than 9" x 14" x 22" (length + width + height) or 45 linear inches (the length, height and width added together).
I just flew United/Lufthansa to munich and back from frankfurt. We were told that my backpack (worn with only one strap over my shoulder and partially filled) was considered my one carry on bag--not my "personal item." This bag easily fit under the seat in front of me. I was asked to check my bag eventhough the only other thing I was carrying on was a garment bag that was completely within their specified measurements (both according to their website and to lufthansa when i called to confirm this). I would not recommend carrying anything larger than a small to medium sized purse as your personal item. My wife had a 21in roll aboard and a larger personal item, but didn't get asked to check either.
I was asked to check my personal item even though it was a partially filled day pack and the only other thing i was carrying on was a garment bag. I flew with United/Lufthansa just a few weeks ago (approx 6 weeks ago). I wouldn't recommend carrying anything larger than a small to medium sized purse as a "personal item."
I used my RS-Convertable bag and a day-packback (Northface) as my "personal" book/camera bag. I think it actually weighed more than my 7kg RS_Bag - which I was asked to put on a scale once with lufthansa... but then it was light enough for me to do both. Dont overstuff the day pack - just put the heavier book/laptop/camera stuff in it. Also - show up early and always smile/be polite - that may help! In smaller regional connection planes they could ask to check larger/garment bag types at the door - but you should get it back when you leave the plane door again - not at the checked area.