They started out with a ~15% margin. How close is acceptable? Behind the scenes the mileage estimates are really a central number with error bars. In this ca

They started out with a ~15% margin. How close is acceptable? Behind the scenes the mileage estimates are really a central number with error bars. In this case the electronics could definitely have come up with better numbers based on altitude changes. And it definitely could have given guidance on speeds to maintain whatever margin is comfortable.