It's the Fourth of July and leaving the country may not be the most convincing display of patriotism, but if you're planning to go anyway you really ought to know about the so-called Fifth Freedom of the air and get ready to celebrate it.

This obscure tenet of international aviation law establishes the principle whereby an airline of one country through multilateral negotiations can secure the rights to transport passengers between two other countries.

Yes, we're talking legal technicalities here, but they translate into some of the best deals in the sky so you may consider this your freedom to express your inner cheapskate, pursue happiness abroad for less, and defend your fashion convictions with a loaded suitcase.

Even in a time of ever longer non-stop long-haul flights, a number airlines opt to make intermediate stops to let off and take on passengers en route. Since these routes are likely to be dominated by entrenched primary players, the carriers in question play supporting roles at best and tend to fly under the radar, at least in marketing terms.

Their bread-and-butter business is getting people from point A
or point B
to point C, so they will often let you hitch a ride between points A and B on the cheap and sometimes even in style. Bottom line is that these airlines have seats to fill with your bottoms, folks, and they're priced to sell.

This all sounds good in theory, so let's do the math:

Say you want to go from New York to Frankfurt, preferably non-stop, for the last week of July. The best non-stop fare you find on Orbitz is almost $1,200.

Now, that's a lot of money, you think, and we couldn't agree more, but with some goodwill and a stopover you get the price down to $971. Well done!

The Orbitz flexible search feature is the best tool around for rooting out good international fares, but they can only show you fares they're authorized to sell and sometimes the airlines simply keep the best deals to themselves.

You know this because we've told you so before, and now we're telling you that Singapore Airlines happens to be plying that trans-Atlantic route daily with roomy jumbo jets.

So you make your weary way over to their site only to make the happy and surprising discovery that a mere $778 can get you a comfortable seat on an airline universally recognized to be the best. The seats are wide-open, so that's at least $200 in easy savings, making it a great deal for your wallet as well as your backside.

These bargains are legion and the savings sometimes legendary, but they can be tricky to track down, so as always we try to do the hard work for you and list them as we find them.

Still, it might behoove you to exercise your Fifth Freedom and do your own due diligence if you plan to travel one of the following routes, keeping in mind that this list is far from complete, subject to change and not a guaranteed good deal, just a good deed in the guise of a guideline: