Several factors come into play:

- It takes several months to change flying patterns, so reduced Western schedule is only just about to start happening

- until mid-January, aircraft were not available to take out of service due to 100% fleet utilization over Christmas

- the parts have a long lead time for delivery, so changing from the original install schedule (which was set almost 2 years ago) takes a minimum of 6 months. Also, besides the IFEC system, all the new seats, in-seat power and a few other small components have to be available to be installed at the same time, so multiple manufacturers have to coordinate parts delivery

Last year saw a single mod line to start with, that ramps to up to 6 parallel lines at certain times this year, but drops back down at peak times during major holidays and summer travel season due to aircraft being needed to fly the necessary schedule.