Disintegration

Most likely you are going to have no issues getting the challanges done bar one. (If you are struggling with the Survival Mission on Mission Cold Comfort just lower the difficulty to the lowest setting and its a cakewalk). The kill 10 flying enemies on Hot Wire (last mission). First of all do NOT attempt this challenge on anything but Recruit or higher difficulty. (the other two challenges can easily be knocked out on the lowest difficulty if needed)

Up to the final section where you need to destroy the electric coils you should have gotten 7 fliers (they are pretty much unavoidable) then you need to do some obscure and specific order of coil destruction to trigger the last 3 fliers. When exiting the hall where your two buddies are waiting on you to destroy the coils face the North first destroy the closest coil behind which the titan camps. Then kill the titan after which destroy the left coil, then the right coil. This should spawn one flier. Kill it and move up one row where you will destroy the right coil and then the left coil which will spawn the last two. If you mess up somewhere just reload your last checkpoint and it will respawn all coils and the titan. Good luck.