I am a civilian contractor and have spent 3 years in Iraq and Afghanistan. With that and my other travels over the world I know the importance of having enough supplies to be self sufficient but at the same time to be light enough to travel easily. With a pair of shoes and 2L of water the pack weighs 24lbs/11kg.
Whenever I fly I try to have a carry on bag only. If I have a checked bag it will be items I can live without such as extra work clothes and bedding. That way if my luggage gets lost I have enough to get by for a while.
This is my bag I use to travel. It is also the same bag I have lived out of for years at a time. It is packed nearly the same. I have made a few additions to it to make it more of a urban survival bag. The bag I use has detachable backpack straps. It is a soft side bag that will fit in any overhead bin in an aircraft. It has one main compartment with two dividers that can be unzipped and folded back, It also has 3 smaller side pockets.
My next project is to build an outdoor survival bag to go alongside this pack. (update 2/26/2014 https://www.instructables.com/id/Outdoor-Survival-Bag/)
Step 1: Sealed Items 1/3
Keep everything organized. I used to keep everything in quart Ziploc bags. When repacking I divided my items into two categories. Rarely used/emergency items and common use items. I vacuum sealed the rarely used items to take up less space. The common use items I put into Ziplocs and or in the 3 smaller backpack pockets.
The hotel soap and compressed towels are throw away items in case I have to clean up in an airport bathroom.
Step 2: Sealed Items 2/3
Some food and basic 1st aid. For airline travel I will buy snacks and water after I am through the security checks.
Step 3: Sealed Items 3/3
I like to have something to add to chemically treated water to cover up the flavor.
Step 4: Basic Medicine and Hygiene
I like blister packs for medicine. They take up less space and sometimes customs inspectors and military inspectors can get picky about open bottles of pills. Sealed packets are easy to identify. I will also have location specific medications such as Cipro or anti malaria.
Not pictured in the hygiene items is a full size bar of soap in a travel container and toothpaste. (I must have left mine behind in a campground shower.)
Step 5: Misc Loose Items
I like having a padlock and cable lock. On a military base no bags are allowed in the dining facility or the PX. If you are lucky enough to find a locker the padlock is useful. If not the cable lock can be used to secure your bag to something like a table, tree or fence. Then I lock the zippers with my TSA lock from the 1st page.
I use the hip pouch or "fanny pack" for airline travel. It is considered a personal bag and can fit under airline seats. I will pack it with snacks, water, small electronics and flight entertainment.
Not Shown quart and gallon Ziplocs
Step 6: Clothing
When traveling somewhere specific I will repack clothing accordingly. I want to have 2 sets of clothes. That way even if I am naked and have to leave quickly I can wear one outfit while washing another. For general use I have:
1x Pair Old Sneakers
2x Pair Socks
2x Pair Underwear
2x Tee Shirts
1x Swim Trunks
1x Pajama Pants
1x Jean Pants
1x Zip Up Hoodie Sweatshirt
Step 7: Additional Items
Depending where I am going and how I will be traveling I might have some or all of the above items with me. If it is airline travel and I have a checked bag I will put most of the items in there. If I only have a carry on bag I will mail the items to where I am going.
For a complete list of what I carry on my person and the items in my new mini survival kit check out my instructable here https://www.instructables.com/id/Making-a-Combo-Whi...
I keep a plastic grocery bag with additional bottles of water next to my bugout bag. I keep everything in my closet where I store the other items in the picture above.
Some of the other items I would recommend for a bob bag, house key, car key, money, prescription medication, tobacco products. Even if you are not a tobacco user grab a pack of cheap smokes and a tin of chew. They are useful for trading.