At 0100 Central Time on Saturday, 03 March, United Airlines will flip the switch, transitioning from its Apollo Reservation System it has used for the last four decades to Continental's in-house SHARES system. Will the transition be smooth? History suggests no.
To be blunt, the history of these kinds of data transitions is horrific. When US Airways and the old America West combined computers in March 2007, travelers were inconvenienced for weeks, and as many as 70 percent of the carrier's planes ran late for days. Tiny Virgin America spent months trying to straighten out its operations after a transition to new software last fall. And despite United's claim that it has done four full-scale dress rehearsals in anticipation of this weekend's change, one usually compliant securities analyst used the airline's recent earnings call to raise the specter of War Games, the 1983 Matthew Broderick movie about a new defense computer that almost starts a nuclear war.
There is really no use now in speculating how things will go, but I would urge you to take steps to prepare yourself for the worst. First, print out your mileage and upgrade balances from united.com before the transition. In case there are any hiccups in the transition of points or upgrades from one account to another, you want proof of what you had with pre-merger United (PMUA).
Second, if you are traveling, look into alternate routings on United/Continental to get you where you need to go. In case of delays, it always helps to have options ready to feed to the agent--at least on United, that can occasionally result in being booked into first class if economy class is full.
Last, avoid checking bags if you can--there are few things worse than lost or delayed luggage and the new luggage processing system may present issues for baggage handlers that at the very least delay delivery of bags.
I'll have some thoughts on the end of United as we know it tomorrow or Friday, but look on the bright side tonight--there is no argument that at least when it comes to websites, Continental has a far better product. Particularly when it comes to booking award travel, the new system will be quite advanced and make it refreshingly easy for consumers to book flights on (and likely lead to a noticeable drop in Star Alliance award inventory).