Lufthansa's policy on carry on, even for international, in economy is as follows:
A piece of hand luggage may not be larger than 55 cm x 40 cm x 23 cm and may not weigh more than 8 kg (17.6 LB).
One personal piece of hand luggage such as, for example, a woman’s handbag, a laptop case or shoulder bag with a maximum size of 30 cm x 40 cm x 10 cm.
While the dimension restrictions are pretty much standard, 8 kg (17.6 LB) is absolutely nothing if you are traveling with a wheeled bag. I, and other FT'ers have personally seen LH gate agents (all over the world) weighing carry on bags and having half the plane take stuff out of their bags. (Of course, it is better if you avoid a wheeled bag in this case, as they usually take up half or more of the allowed weight)
Other airlines such as Air Canada have similar policies. See all the discussion and links posted
here.
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I have come up with a possible strategy for those of us who do not want to/can not check in bags on week long trips:
using a large packing cube with a handle as a personal item:
That is, you would pack your bag as you would normally, go over the weight limit, and have a packing cube (filled with your heaviest stuff) ready to pull out of the bag as a personal item to put under the seat.
You carry on might get weighed or not, if it does, you can pull it out, board the plane, and put it back in the bag

, or store it under the seat.
It is all about calculating the exact weight to put on the packing cube so that when you take it out, you are within the restrictions for your carry on.
Both of those models conform to the personal item restrictions on dimension, and there usually isn't a restriction on weight:
http://shop.eaglecreek.com/packit-sp...ube-set/d/1281
http://www.ebags.com/product/ebags/l...-3pc-set/48438 (you probably want to use 2, one wrapped in the other with these ones as they are see through)
Advantages:
- Very cheap.
- Very lightweight.
- Maximum storage volume compared to other personal items (messenger bags with compartments, etc)
- You probably already have one.
- Not having to carry an extra item when outside the plane. Just put it back in the carry on upon landing.
- If you are not over the weight limit with your bag, taking it out frees up space to bring back souvenirs on your return trip.
Disadvantages:
- Not made to handle a lot of weight (not that you should put much in there anyways, just enough for your carry on to pass inspection)
- Handles are not of the highest quality.
- Doesn't exactly look good, but I don't personally care. Somebody could make a decent looking one that doubles as a personal item. Or just take a messenger bag, an actual 'personal item' with you.
Any thoughts on this, has anybody actually tried this? Any other downsides to this?
Of course, I know the obvious answer is take less stuff, but sometimes it isn't possible and you have to get creative.