Originally taken from here. Corrections and additional info by me.
Prison Break Heist Guide - Grand Theft Auto V (GTA 5) Online
Complete walkthrough of the prison break heist in GTA V Online.
Setup Cost: $40,000
Reward: ~$500,000 - depending on difficulty
Playing on normal difficulty, you get 1 extra life. During the heist, the pilot death / vehicle destruction is mission failure.
Playing on hard means any death fails the mission.
Your first real heist will require 4 players to complete. Your task is to liberate a [s]scientist[/] chemist named Walter White from prison using misdirection and a little shooting. There are 4 setup phases and one final phase to the heist, so get ready to buckle in a for a little while.
The Setup
The Plane – Your first task is to acquire a plane from Mackenzie Airfield. The mission set up selects a designated pilot, and the ground team. You will need to make your way over to Mackenzie Airfield in Sandy Shore. Be careful not to sight your weapon over any enemies while you’re getting in to position. Doing so will activate them. Be careful of incoming enemy vehicles flanking you. Once you’ve cleared out the armed guards, the designated pilot will hop into the plane and fly it back to Lost Santos International Airport. There, he will need to land the plane and taxi in to the Devon Weston aircraft hangar and stop on the marked spot. While the pilot is flying the aircraft, the ground team will be required to leave the airfield area. Once they are out of the area, they can either use their quick menu and observe the pilot, or use the bulldozer from the airfield to completely mangle the pilot’s personal vehicle.
The Bus – If you haven’t noticed you need a lot of vehicles for this heist. The bus will be marked on your GPS when you start this setup mission so head to its location. It’s handy to have someone take out the escort chopper with a homing missile while someone else takes out the bus driver and nabs the bus. You will then need to lose your stars and drop the bus off at the storage location.
Your best bet is to take the bus off road because you are not out running anything with its extremely slow speed and acceleration. After everyone has lost their wanted stars, you will still need to keep your distance from any law enforcement, which will give you a one star rating after sighting you.
The Station – This setup is a little more complicated and requires two teams of two to complete, the cops team and the cargo ship team. The cops team need to get their hands on a police cruiser and then head to the police station marked on the map. There are many ways to accomplish the task, but bear in mind that you will need to lose any wanted stars before you can continue with the mission. Once you have lost your stars (if any), you can head to the police station marked on your map. Once there, head inside but do not open fire or take a weapon out. Simply head to the marked bus schedule on your map, pick it up and calmly walk out of the station. If that went well you will be prompted to park the cop car under an overpass and destroy it to get rid of the evidence.
The cargo ship team has the simple task of stealing a car from a heavily guarded cargo ship. No advanced strategies here, kill the guards, steal the car and return it to the marked location on the map to complete the setup. We’ve found the simplest way to do it is to climb up one of the cranes, snipe a few of the guards, drop to the top of the cargo containers on the ship with a parachute, and grab the car. You will have to fight off some vehicle attacks on your way out. Be careful of NPCs trying their damnedest to veer in to you while you’re escaping.
Wet Work - The last setup mission has you getting your assassin on by taking out some lawyers. Again there are two teams of two for this mission, the City Hall team and the Mansion Team.
The City Hall team have to head to the roof of city hall using the ladder marked on your GPS. Shortly after arriving on the roof, two lawyers will pull up in a car that you must kill. They most effective way to deal with them is to assign one player a lawyer and then time your shots to take them out at the same time.
Spend some time taking out the cops attacking you. Once you’ve gotten rid of the immediate cops, climb down and get in to your hopefully fast getaway car. Escape the cops sight, and go hide in a parking garage until your wanted level is gone.
The mansion team has to kill Popov. The problem is that he is surrounded by guards, and if they are alerted, Popov will run. If he escapes, the mission fails. Some people like the stealthy method of breaking in to the mansion without alerting the guards (killing them silently), but the easiest way we’ve found is to alert the guards causing Popov to run, catching him and killing him quickly. He doesn’t always use the same path when he runs, so be alert for him.
The Breakout
After deciding who gets what percentage of the heist rewards (bearing in mind the heist initiator spent $40k of his own money and didn’t get any cash during the setup missions), it’s time to start the big show. First off you will have to assign each player a role for the heist. The four roles available are Demolition, Prisoner, Prison Officer, and Pilot. Communicate with your team, find out their strengths and weakness and assign the roles to suit.
Demolition
Head to the Prison bus and take out the driver. Once he’s taken care of, you can take the bus to the marked location at Sandy Shore airfield, and destroy it once you’re there. Just before you arrive at the marked location, notify the pilot that he can take off. Use a sticky bomb or gasoline to destroy the bus, and hop in to a nearby vehicle. Head to the other end of the airfield where there will be a Buzzard ready for you to steal. It is marked on the map. There are two guards by the buzzard. You can easily shoot them as you drive up. It will be your job to shoot down jets that are trying to destroy the plane. Once the pilot is in your airspace, gain height and try remain near the airfield (STAY AWAY FROM THE PRISON), as you will have to head to the eastern side of the prison to help them as the ground team breaks out of the prison. The pilot should circle you, bringing the jets close enough for you to shoot them down with your missiles. When the prison team reaches the armored vehicles, you will then be able to break off and go assist them by shooting down the police choppers and destroying any other vehicles that are causing trouble for the prison team. Cover them until they can get to the plane. Destroy any police vehicles that could damage the plane or prevent it from taking off. As soon as the plane is in the air, keep covering it until it is out of reach. You will need to lose your wanted stars, and then head to the marker on your map. There, you will need to land on the beach and collect your team.
Pilot
The pilot is the getaway driver in this heist and after he picks group the Velum he must go to Sandy Shores Airfield to wait for the other team members that will be heading there for an extract.
You have an 8 minute timer to get to the Sandy Shores airspace. As soon as you enter the airspace, jets will be scrambled to shoot you down. If you get there too early, you will have to avoid a number of missiles that the jets will fire at you, and you will also have to try avoid their guns. The demolitions player will eventually get in a buzzard and will be able to protect you from the jets.
The easiest way to do this is to waste time at the airport. Wait until the timer reaches 4 minutes remaining before getting in to the plane. By this time the demolition player should be already at the buzzard, ready to go. Fly towards the marker on your map. If there is still more than 1:30 to go on your timer, circle over the Vinewood sign before heading in to the Sandy Shores airspace. As soon as you get in to the airspace (a little past the mountain where the Vinewood sign is), your timer will stop, and jets will be scrambled. If you have timed this correctly, the demolitions player will ascend in the buzzard and start shooting down the jets. To make it easier on yourself and the demolitions player, simply circle the buzzard at a decent height. Your plane is the slowest piece of crap in the game and is difficult to recover from an accidental dive, so maintain that height! Once the prison team has reached the armored vehicles, you will be tasked to land so that the prison team can get on board. Also, the demolitions player will head over to the prison to help cover their escape.
Land the plane on the Sandy Shores airfield, being sure to leave enough space for you to take off again. Open your side door by pressing E (or right d-pad if you’re using a controller). Wait for the prison team + Walter White to get on board. Walter White will get in as co-pilot, since he will be taking the plane a bit later on. As soon as they are inside, accelerate and take off. Hopefully there will be no police vehicles blocking your path. Once you’re in the air, gain as much height as you can, and get away from the cops. Avoid flying over the prison. You should soon lose your wanted levels. Head to the marker on your map. This is the drop zone. It is fairly high up, so don’t bother losing height. As soon as you are in the vicinity of the drop zone, you will jump out the plane and parachute to the beach. Wait for the buzzard to pick you up. Get in and enjoy.
Prisoner/ Prison Officer
The prisoner and prison officer will be infiltrating the prison using the bus you stole in one of the setup missions. To get into the prison, simply follow the way point to the front gate, which should open right up for you. After you’re in the prison get out of the bus, and WALK to the left front corner of the bus. The PO can shoot the immediate two guards, while the prisoner can use his pistol to assist with the further guard. You will become wanted and the officers will open fire on you. Take them out and head to the scientists location on your GPS. Once the area has been cleared, the prisoner can pick up weapons and some armor drops.
It will be a tough battle to get out of the prison once you get to [s]the scientist[/] Walter White. Once you release him, head towards the prison entrance with the scientist in tow while killing any NOOSE agents you see. Near the entrance there will be an armored truck you can get in. Once you’re in, high tail it for the airfield. Your demolitions player will help give you cover at this point.
Cops will automatically spawn at the airfield after you break out of the prison, so it may be a good idea to send the buzzard ahead to clear them out before you roll in with the scientist. When they’re taken care of, head for the pilot who should be waiting there for the plane and take off.
If everyone performed their role successfully, you should be in the clear and a whole lot richer!