737 Max Delivery Rate / Backlog
Throughout the period that the 737 Max has been grounded, Boeing's production line has continued to build, but not deliver, new aircraft. There is now a significant number of aircraft waiting for airlines to accept these new aircraft. I am assuming that Boeing will eventually come up with sufficient modifications to gain clearance by major aviation regulators
I understand that airlines are limited as to how many new aircraft they can effectively absorb per month. Thus the backlog of parked aircraft cannot be cleared immediately
What are the major constraints that cause this ? Lack of crew ? Time needed to sell tickets before aircraft can go into service ? Something else ?