Today it is official.

United Airlines will merge with Continental Airlines under an agreement that somehow sends over three billion dollars in UAL stock to shareholders of Continental.

And with the stroke of a couple of pens and huge legal fees, the largest airline in the world is formed.

This is not the first attempt to find success out of failure, and in the current airline economy there are not too many success stories to turn to around the world, and certainly not in North America.

Given the fact jobs will be cut, two cultures will have to learn to like each other quickly, and an arranged marriarge will have to see its partners consummate quickly after a brief kiss on the cheek, expectations for success may be dubious.

Let’s take a look at some history. The website airline news highlighted some of the marriages and we will add our analysis of the impact of these previous unions.

In 2001 Japan Airlines and the Japan Air System thought the impact of 2001 might be buffered with a merger.

Less than 10 years later the new JAL essentially goes bankrupt even as the pickup and sweepup operations continue today.

Likewise in 2001 Canada’s National Airline took over Canadian Airlines.

Air Canada executives, who many felt couldn’t run a fleet of Lego aircraft, proceeded to drive it into bankruptcy protection.

Today Air Canada, while bigger, is still a shell of its former self and the glory that it once held in the eyes of its customers has been tarnished beyond recognition.

American Airlines took over TWA and proceeded to go into its own tailspin.

Whether they can be called a complete success of not but in the Air France takeover of KLM Royal Dutch Airlines, and perhaps recognizing the French and the Dutch have some historical issues between them, have kept the operation of the two airlines separate under one umbrella name.

With more recent acquistions like British Airways agreement to merge with Spains Iberia Airlines, more time needs to pass to measure results.

But given the recent financial records of BA and its current challenges, it is hard to foresee much to celebrate about in the near term.

Similarly the death of the international brand North West Airlines as it morphed itself into the Delta logo has not shown any early signs for celebration, but there always seems to be that at the first couple of press conferences.

So as UAL and Continental clink champaign glasses, just watch for the few drops that hit the carpet.

History shows those drops can flood the place.