Although the CRSs simplified the task of maintaining airline data, they brought in new problems
In order to handle increasing passenger traffic, large computer systems were required for CRSs. This created a cost burden for airlines, especially the smaller ones which did not have enough money to spend on expensive mainframe technology
CRSs were airline specific. This required travel agencies who wanted to sell tickets for multiple airlines to have individual connections to each airline separately
Availability and fare searches across airlines was not possible since each airline had its own CRS. Since most passengers were interested in purchasing the cheapest fare rather than a specific airline, travel agents had to spend inordinate amount of time to determine cheapest fares across airlines