Additional cabin handbag on flights

From experience with a number of airlines in Europe, your laptop bag does not count to your cabin baggage limit. It's treated similarly to a lady's purse, so if it indeed looks like a laptop bag (i.e. has an arm strap and everything), it should be allowed without a problem.

Please note that some low-cost companies (cough Ryanair cough) still insist that you need to have exactly one bag, regardless of its function.

Discount/cheap airlines in Europe (Ryanair, Wizzair, EasyJet(?)) are very strict about "1 item of hand luggage total" rule. Even if you want to carry 2 very small items instead of one maximum size it's not allowed. I've seen multiple "scandals" with airport personnel enforcing this rule and passengers trying to reason with them based on common logic. Passengers never win and in several cases it ended up with passengers being escorted from the airport. In best case scenarios it ends with 20-40 Euro luggage fee and in-place repacking.

The bottom line is - check the rules of the airline you are flying with and obey them instead of relying on common sense.

After seeing these incidents I try to travel with either only one bag, or, at least, in a configuration that can be assembled into one bag.

In North America, using Star Alliance airlines (Air Canada, United, Continental) I have never had an issue with one backpack (technically my laptop case, since my laptop is in it - this is the sort of backpack you get at conferences, not the kind you go hiking in or camp across Europe with, but it's full of stuff beyond just the laptop) and one small bag (labelled a "tote" by the vendor) with clothes etc in it. I have seen people with roll-aboards that could have easily held both my items. When I go for 4 days or less, I go carry on only :-) However when I get onto a very small plane, I sometimes gate check the tote, because their overhead compartments can't hold much more than a coat.

In my experience, the only practical criteria is that the "personal item" has to fit under the seat in front of you, so that it does not take up space in the overhead bins.

Be aware that RyanAir, EasyJet and many other LCC (low cost carriers) are EXTREMELY pedantic about the one piece of cabin luggage. This includes a jacket you may be carrying, a hat, a netbook, anything. It all has to fit in one piece of valid-sized luggage, or be checked. And if you're trying to check when you reach the gate, you're in trouble :/

There is no "rule of thumb" for things like this but I can probably put a few guidelines:

1. If it's of the size of the small suitecase it's probably too big.
2. You shouldn't be able to roll it.
3. Don't stuff your back pack as you would a suitcase it is likely to be frowned upon.
4. A small bag looking like a dufflebag is probably not a good idea.

Beyond that you are probably at the mercy of the gatekeepers at the airport.

United Airlines sizer now includes the personal item.

Published carry-on limit: 9"x14"x22" Actual sizer dimensions: 10"x15"x23"

Published personal item limit: 9"x10"x17" Actual sizer dimensions: 9"x11"x18"

From http://www.flyertalk.com/forum/united-airlines-mileageplus/1449269-rollaboard-luggage-meets-uniteds-carry-sizer.html

For other airlines, yes, the rule is usually it needs to fit underseat. A neat trick also from Flyertalk: look for pet carrier sizes. Those also need to fit underseat.

Most European low cost airlines have wised up by now -- probably I am not the only one who will squarely refuse to fly if two bags are not allowed. (Both of my bags are quite small). This typically is an extra thrown in with some more expensive kind of fare -- you can't buy a second bag by itself. Wizz Air policy

PASSENGERS WITH PRIORITY BOARDING
are allowed to carry 1 additional personal item in addition to the small or large cabin bag.

Easyjet

easyJet Plus, FLEXI fare, Upfront and Extra Legroom customers
Plus ONE additional small under seat bag (For example a handbag or laptop)
Maximum size of 45 x 36 x 20cm which will need to be placed under the seat in front.

Even Transavia have found out which side of the bread is buttered and now say:

If you’d like to take an extra piece of hand luggage with you, we recommend the Max fare. These are the conditions:

1 piece of max. 55 x 40 x 25 cm and 1 accessory, such as a handbag or laptop bag, that fits under the seat in front of you. The weight limit is 10 kg, divided over 2 pieces of hand luggage.

(back in 2016 April they insisted on a single luggage)

In 2016 July, WOW Airways unblacklisted itself and now allows for a personal item and in a refreshing change they even display the size of it:

In addition to this, guests may board the plane with one personal item such as a laptop, a small purse or camera bag (max 42x20x20cm); and a duty free shopping bag.

In 2017 September, Ryanair changed their policy and while they still allow for two bags, the big bag now goes into the hold free of charge unless you bought Priority boarding. This is different from the airlines above where you needed to pay to carry the small bag on board, Ryanair wants you to pay to carry the large bag on board. (I personally would not be surprised if other airlines would follow suit to speed up boarding.)

Lots of now outdated information here - in defence of RynaAir who I just flew with, they never measured or weighed my main bag (I wasn't hoping they didn't, it would have fit just fine in their sizer) or my smaller additional bag they now allow free too (laptop bag probably would have been pushing it though). I think this is the equivalent of a handbag for women, but the sizer for this second carry-on is very generous.

They also didn't mind that I wrapped my coat round my waist and had an SLR and hat round my neck. It's not all doom and gloom!