The business cycle is to what you allude. Convention is the business cycle is around seven years between peaks. We are currently due excessive money printing (Quantitative easing) about eleven years into the cycle and well overdue for a correction..
When is the big question
It is this cycle the IR practitioners (a dark art if ever there was one) use to
time their delay to negotiation in order to simultaneously threaten to take away any nominal salary(payment for delay) and drive through concessions. Australian authors have done a lot of work in this field for those inclined to do some research
Organised labour is not really ahead of the cycle, rather they react to implied threats, with the possible exception of ALPA in the USA who with Chapter 11 provisions have some forewarning what is upon them. Much research has been done into the topic and it is well known in corporate circles have to control 'negotiation' with cancelled meetings the norm.
This time however the underlying forces (business cycle) correction may be sufficient to delay the shortage, but it will not be curtailed by a cyclical correction. The hope is that in providing a glimpse from the other side of the curtain, pilots consider the veiled threats and whispers as just that.