Actual enforcement of carry-on luggage weight

It depends on a variety of things.

• The agent at the check in counter.
• Airline(s) you will be flying.
• The aircraft(s) you will be flying.
• How nice you can smile.

I usually travel with only a carry on bag, so I'll write down how I determine of the airline is going to be relaxed about baggage sizes.

First, if the airline is a budget airline with no free checked in baggage allowance, you can expect strict regulations. Your baggage will be weighed, and measured (you have to put your bag in a container. If it fits, you are good). They basically want you to pay for checked in baggage whenever possible.

If you can smile a bit at the check in agent, and convince him you absolutely need to take it onboard, you can actually do so. One if my tips include saying that I have a transit to make (in another airline), so a carry on would be quicker, there is a good chance they will allow you to take it onboard.

Try to be reasonable as well. Overhead bins in most aircrafts can only hold about 40Kg (A recent A320 had a sticker there saying max weight of 35 Kg). Besides, the carry on should be smaller and you should be able to carry it yourself. If you can't, someone will force you to check-in the bag.

Bottom line, if the airline is a budget airline without free checked in baggage allowance, keep it bellow 7 Kg. For other airlines, +1-2 Kg would be OK if you carry a normal size bag, depending on how nice you can be to the check in agent.

Above and beyond anything else, it depends most heavily on the route being flown. If the route is quite full / popular then there is stricter checking of the weight and dimensions.

The next biggest factor is the airline.

This has been my experience flying with a majority of airlines; and the only thing I could think of that was common across them.

Here are some examples:

Kuwait - Dubai - Kuwait

This is a very popular route; especially as people jet off to Dubai to do shopping over the weekend (or even a day run).

If you fly this on the low cost carriers (which are point-to-point), then they don't care about your carry-on weight - as lot less luggage to deal with. They do care about the number of items you are carrying.

If you fly this on Kuwait Airways, they also don't care about your carry-on weight, but they do enforce the carry-on item limit.

The Emirates flights on this circuit for the outbound leg are stricter on the carry-on luggage. Sometimes, they will take it from you at the gate if the flight is especially full. That's because these flights are feeder flights for the international departures out of Dubai.

Kuwait (or Dubai) - UK - and return

This is another popular route, and the enforcement is extremely strict here. Especially on BA - which fly their older 747s on this route from Kuwait.

If you take the same flight on Kuwait Airways, then they will also enforce the weight limit. In fact, they have a guy standing before immigration with a scale and if your bag looks heavy he will stop you.

So it depends entirely on the segment and the airline.

It depends more on the route. Generally I never had problems with this (and I carry a very big hard drive that weighs a lot), but in some flight from Miami to Bogotá (Avianca), I had problems with this.

I just removed things in counter from bag and added again when I left it.

Also, low cost airlines are more strict in this than "normal" airlines.

Many airlines have a weight limit for carry-on luggage and it seems to vary considerably more than the size-limit. I've seen anywhere from 3kg (Amazonas) to 20 kg (US Airways) specified. Delta has a limit that depends on the airport! Several specify only a size-limit.

In all cases, I have NEVER had my carry-on or personal item weighed or checked while boarding. It comes down two things: Mine are rarely close to the maximum size, although I do exceed the weight limit easily but since they do not look heavy and I don't act like they are, it has never happened to me. Systematic checks of carry-on weight exist in some placed but among over 200 flights to 55 countries, including different airlines to the same country, plus dozens of regional flights.

The time I flew from Uyuni to LaPaz was worrisome. I had already checked-in, they took my checked luggage and then let me pass to the security check which as manual. No X-ray. So the security officer lifted my bag and noted it seemed heavy, so he asked. I said it weighed 3kg :) And he let me pass. It did not look like there was a scale at that point to check. Plus, I would have been at an impasse since Amazonas forbids placing valuable in checked baggage and so I had my heavy valuables in my carry on.

There is probably an element of luck involved but as with all such things you can make your own luck by carrying bags which simply do not look heavy. Sometimes you may have to do some shuffling. A fellow photographer is sometimes caught with an excessively heavy bag, so he places a camera and the heaviest lens over his neck and additional lenses in his coat pockets before asking them to weigh again. He says that we has gotten some funny looks but he was always allowed to pass since you can carry certain things on your person.