Have you ever been involved in such a migration?
It’s invariably a complete clusterfuck.
It’s invariably a complete clusterfuck.
[0] https://amadeus.com/en/insights/blog/celebrating-one-year-fu...
My initial approach would be to weed out anyone with that point of view before any work took place (the "not HR friendly" part being to be purposefully exclusionary). The only way a problem of this scope/scale can be solved is by a team of people with extremely thick skin who are comfortable grabbing a beer and telling jokes after they spent the day telling each other to go f*ck themselves.
The amount of wise-cracks and beers your team can handle after a work day is not the determinate factor in success. /Most/ of these organizations /want/ to migrate these systems to something better. There is political will and budget to do so, these are still inglorious multi-decade slogs which cannot fail, ever, because failure means people die. No amount of attitude will change that.
Of course it isn't. But it's a starting point for building a team that can deal with what you describe (a decade-plus long timeline, zero room for failure, etc). If the people responsible are more or less insufferable, progress will be extremely difficult, irrespective of how talented they are.