Saints Row: Gat out of Hell
45 Achievements
20-25h
Epic Flight Quest
Fly from the roof of Snowball's Chance to Sinterpol HQ's roof, without landing
3.9%
How to unlock the Epic Flight Quest achievement in Saints Row: Gat out of Hell - Definitive Guide
Sinterpol HQ can be found in "Rebellion Square" towards the southwest, near the highway.
I highly recommend you have ALL the Flight Upgrades, although they aren't 100% necessary, they do help a lot. You will need a good amount of stamina and at least 3 flaps to get there without major problems.
Now go to Snowball's Chance Hotel & Casino, and make your way to the roof of the tallest part. Use your map to mark the location of Sinterpol HQ. Charge your jump, and begin sprinting in a circle until maximum speed and then jump out towards the middle of the map. At the peak of your jump, begin flying. I recommend 1 flap pretty early, another soon after, and your 3rd and final flap as you pass the large floating building that you pass at about the halfway mark. Maneuver your way around the building towards the marked building. I recommend that you fly directly over it and then use "Flight - Hover" above it to get the achievement/trophy to unlock, although hitting the the very peak of it will also work. If you miss the peak, it will most likely not work.
Note: From personal experience, it will not work if you dodge spire missiles along the way.
I used the following flight upgrades:
EFFICIENCY 2
FLAP 4
LAUNCHING JUMP
POWER 2
The quickest path is straight through the buildings especially if you don't have all upgrades. Try to spare one flap for the landing. This way you can jump in the air and coordinate the landing. If you get lucky like me, the achievement pops by simply getting very close to the rooftop.
Fly from the snowball's chance roof to sinterpol HQ's roof without landing.
This trophy earned for flying from the top of the Snowball’s Chance Casino (large white building that looks like an upside down cone) to the rooftop of Sinterpol HQ in one go without touching ground in between. Once you have upgraded your flight this is easy to do as long as you know which roof you are going to. This can be completed in either direction (starting at Sinterpol HQ and going to Casino), of which going to the Casino is probably easier due to it being a much larger and easier to spot target.
The following video by Maka shows the locations on the map to fly between as well as an explanation of how you should go about your short flight between the two buildings.