"Plant signal boosters around the city to triangulate Karen's position"
Continuing this story-arc, we need to go for a helicopter ride with E-Man to plant some triangulation devices around the city - then we'll phone frank and find out where he is. E-Man drops you on the first helipad - you need to parachute onto it (steer so that you land safely on it and make sure you open your parachute!). Then, walk into the waypoint to plant the first signal booster.
This causes a huge police presence to appear. E-Man has to pull out, meaning we're on our own for the final two boosters. To get off the helipad, simply jump off the edge and use a parachute to land safely. You may need to steal a police vehicle at the bottom or secure a vehicle. Then, head to the second booster.
one of them is in a railway station, which you can access via the stairs. The other one is on a gangway next to a large storage container, again accessible by using some stairs. They are all up high compared to road-level. You also have to compete with a regular high wanted level during this mission.
After you have planted all three of the boosters, you will phone frank. His position will be triangulated, and you then need to race to the location in the time limit so that you can detect where exactly he is.
It turns out he's at the City of Saints Casino. That gives us something to focus on for the next mission.
Reward: G350,000, Respect: 1,365,000