Flying can be confusing these days, with rules and regulations that seem to change on an almost daily basis. If you are flying, one of your most important concerns is the weight and size of your carry on bag, as well as what is allowed on board and which items are prohibited. Knowing what is allowed on a carry on is important because it can help you save time at the airport.

One reason that the carry on policy is confusing is that it not only varies by airline, it can vary depending on your destination. Whether you are in first class or not also influences what is allowed in your carry on. The Association of Flight Attendants has been campaigning for some time for a consistent carry on bag rule, but to no avail. The best advice is to carefully check your airline’s website for their rules and if something is not clear, call them. You should also check with the TSA (Transportation Security Administration) before you travel, for the most up to date information.

In general, most airlines still allow you to take one carry on bag as well as what they call a personal item. These items include a backpack, purse, laptop or camera. The maximum allowable size of your carry on bag can vary, but as a rule of thumb, it has to be able to fit under the seat in front of you or in the overhead compartment. The maximum weight limit on the carry on bag is usually around 40 pounds; the maximum size usually around 45 linear inches. This is defined as length, height and width added together.

There is not really a clearly defined size or weight limit on the personal items. Some passengers see it as a way to take two carryon bags, but unfortunately, this limits the available storage space in the overhead bins for everybody else. At least one airline has taken steps in an effort to enforce the carry on policy. In early 2008, Delta announced that they would label all carry on items for international flights with a tag indicating that they had been approved to carry on board the flight.

Many passengers are still understandably confused over the rules concerning liquids in their carryon bag. You are still allowed to bring liquids onto the plane with you, but they must all be in containers holding 3 ounces or less. All of the containers must be able to fit inside a one-quart size Ziploc type bag. The definition of a liquid includes creams, lotions, gels and shampoos (you can only take a drink on board the plane with you if it was purchased after you passed through security).

The plastic bag then has to be passed through the X-ray screening device separately. If you have liquids in larger containers or too many containers to fit in the one plastic bag, you may have to put them in your checked luggage. Exempt from this 3-ounce rule are baby formula and medication and if you do carry on medication, it should be in the original labeled container. It is also a good idea to take a prescription or doctor’s note, just in case you are asked for it.

So what should you pack in your carryon bag? It is a good idea to have all your essentials in your carryon bag in case of delays or the airline losing your checked bag. In your carryon bag, you should include your prescriptions, basic toiletries, plane tickets, passport and any other important paperwork. A change of clothing is also a good idea. Some experienced travelers only pack a carry on and do not bother to check a bag. This saves time and eliminates the possibility of the airline losing their checked bag.

The importance of packing lightly and efficiently cannot be stressed enough and many airlines are flying smaller planes on their routes, which mean overcrowded flights and less carry on space.

Packing a carryon bag can be a difficult task due to the laws that seem to change regularly. The best way to ensure a stress free flight is to research your airline ahead of time because the airline should have their rules available. This allows you to know exactly what is allowed. The basics of packing a carryon bag include remembering that liquids have to be in a 3oz bottle. It is also a good idea to pack clothing, necessities such as medication, a passport and other important documents. Many problems can occur with checked luggage and it can sometimes become lost. This is the most important reason for including your most valuable items in the carryon bag. Consider these tips next time you are planning a flight, but you should also check with your airline.