Some airlines allegedly reduce fares on certain routes to a level at which they lose money, in order to drive competitors off those routes  However, this method of eliminating competition cannot be profitable in the long run
Once an airline successfully implements this method, any attempt to recoup the earlier losses by charging high fares on that route for an extended period would only provide competitors with a better opportunity to undercut the airline' s fares
On deciding to stop serving particular routes, most airlines shift resources to other routes rather than reduce the size of their operations.