Mr. Maurice Quinn:

When one has a jet or any highly sophisticated piece of equipment, it comes with service intervals. We knew, for example, that in 2018 or 2019 we would have a major job to do on the engines. There are certain jobs that have to be done every year and certain jobs that come up to be done, on a timely basis, based on things like the number of landings, number of flight hours and so on. One knows the jobs that have to be done and therefore, one can cast ahead. Unanticipated maintenance costs emerge when something arises with the aircraft which would not, in the normal course, arise through general use. We knew that the amount of unanticipated maintenance work required would increase the older the jet got and that is what transpired in terms of the corrosion and so forth.