Question: my understanding is that the purpose of MCAS is to make the 737 MAX behave very similar to prior 737s in some unusual flight situations. There are two main reasons for this:

(1) Existing 737 pilots would not need to be recertified for the MAX. They would just need to read a short document that updated the procedure for handling runaway trim.

This would make the plane more attractive to airlines because it meant not having to pay for expensive recertification of pilots, and

(2) The plane itself would not need to be certified as a new aircraft type. The requirements for certifying new tapes change over the years, and older planes like the 737 would not meet today's requirements. By making it fly similar enough to the existing 737s, it could be classified as a variant on the existing model and be grandfathered in on the old certification.

Certifying a new type is very expensive and takes a long time.

My question is this: how long does the MAX have to be grounded before the costs of it not being service end up more than (1) the costs of recertifying pilots, and (2) the costs of making the other design changes that would be needed to certifying as a new type under current rules and then getting it certified?