Originally Posted by BiggD
Maka was telling me the same. Well, that least least 3 of them were nearly impossible.
Which aircraft are you using? I've read the Buzzard is the best choice for the achievement.
I used the Frogger for 48/50 bridges, but then had to change to the Buzzard for the last two because the propeller is just too big to fit through the gap with the Frogger. The bridges are really easy though, so there's no problem there.
For the Knife Flights, I used the red plane from the Airstrip (the one used for Arms Trafficking). The majority of the KFs are easy, but there are some really frustrating ones, like the one where you have a gap that is only slightly wider than your actual plane, and one where you kind of slither around the building.
Abusing the Quick Save feature is a massive help while attempting them, because you will die quite a few times.