Boeing made a “massive miscalculation” over how quickly they could get the 737 Max back in the air, according to Scott Hamilton, an aviation industry consultant with Leeham Company.
He told the Wake up to Money programme that the company originally thought it would take about three months before it could start flying the 737 Max again.
He said there have been delays because the final software package to fix the problems with the plane has still not been handed over to US authorities for testing and approval, and after that it will still require approval by international authorities.
Mr Hamilton thinks the $9bn estimated cost to Boeing of the problems “could easily double”.