Still amazed someone could fly for 4 hrs on an early era IRS with no GPS or DME updating, make up an uncertified approach and fly down to well below MSA. Drift on those old IRS must have been in the order of 3-6 nm an hour. So doing the homemade IRS letdown may have put him 12-24 miles off apparent track anyway with the IRS still within tolerances. And without DME updating who knew where they actually were.
Another reason why AirNZ attached so many preconditions to descending below MSA which the crew ignored.
I'm impressed so many on here would have happily done the same.