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Airship Down is an Institute main quest in Fallout 4. In this quest, the Sole Survivor, along with an army of synths, storms Boston Airport in an attempt to cripple the Brotherhood of Steel. This is done by hacking Liberty Prime into targeting the Brotherhood of Steel as Chinese Communists. Liberty Prime then destroys the Prydwen via his dual eye lasers.

Quick walkthrough

Institute main quest: Airship Down
Speak to Evan Watson or Doctor Li.
Use the relay to reach the Boston Airport.
Infiltrate the Airport.
Destroy the Brotherhood generators.
(Optional) Place Teleport Beacons
Reach Liberty Prime.
Defend the Synth hacking Liberty Prime.
Evacuate the Airport
Reward: 600 XP
Leads to: Nuclear Family

Detailed walkthrough

Doctor Li or Doctor Watson greets the Sole Survivor and then leaves Rosalind Orman to explain the details of this quest. She explains that the target is the base of the Brotherhood of Steel operations in the Commonwealth - the Boston Airport. It is shielded by an electromagnetic shield that makes it impossible for the Institute to teleport troops into the base. The plan is that the Sole Survivor will take down the field by infiltrating a poorly-guarded part of the airport, and from there work a way through to the generators and destroy them. For each generator that is destroyed, the Institute will teleport some synths into the base. The player character is provided with a couple of Institute beacons, which are used to relay synths to the location in which they are thrown.

After that, the Sole Survivor will go to the main target - Liberty Prime. Doctor Li explains that it is an old weapon, and also tells about her role in making it operational. Working with Liberty Prime has given her good knowledge on how it works, which will now be used to manipulate it. Rosalind enthusiastically explains that a synth has been programmed with a computer virus and will transfer it to Liberty Prime, making it believe that the Brotherhood airship the Prydwen is a communist vehicle. The Sole Survivor is to escort that synth safely to Liberty Prime.

Following the conversation the player character is relayed from the Institute to the airfield in order to execute the plan. Firstly, one fights their way to the generators, and then to Liberty Prime. They then climb up to the head of the robot so that the hacker synth can begin uploading the virus. The player character must then defend the hacker against a massive assault from both the air and ground. Before finishing the upload, Elder Maxson attacks via a vertibird. If the vertibird is destroyed, he will fight on the ground. This gives the opportunity to obtain his Elder power armor and his unique weapon: Final Judgment. When the upload is complete, Liberty Prime will announce that it will attack the "communist" vessel, and fires its eye laser at the ship. As the ship begins to fall, the Sole Survivor will be teleported a short distance away to observe the fiery wreckage.

The quest completes, and the next quest starts.

Quest stages

Quest stages
StageStatusDescriptionLog Entry
10 Speak to Doctor LiI need to work with members of the Institute in order to devise a plan for getting rid of the Brotherhood of Steel.
15 Speak to Doctor Watson (If Doctor Li is no longer in the Institute)I need to work with members of the Institute in order to devise a plan for getting rid of the Brotherhood of Steel.
30 Use the Relay to reach the AirportThere are generators at the airport preventing the Institute from relaying synths directly to the site. They need to be destroyed.
33 Infiltrate the Terminal
35 Destroy Brotherhood Generators
40 (Optional) Place Teleport Beacons
50 Reach Liberty Prime
60 Defend the Synth hacking Liberty PrimeWith the Brotherhood's defenses compromised, I need to defend the area around Liberty Prime while he's being re-programmed.
70 Evacuate the Airport
200Quest finishedQuest completeIt's over. The Brotherhood has been annihilated. I can safely return to the Institute
1500Quest failedQuest failed

Notes

  • The higher the player's level is, the stronger synth variants will spawn. Doing the quest above level 71 will cause synth eradicators to spawn, which are on par with Brotherhood knights.
  • Brotherhood soldiers will keep spawning until the virus upload is complete.
  • Advancing this quest in any way marks the end of the Sole Survivor's ability to become banished from The Institute in time to follow the Commonwealth Minutemen mission line. As long as the player backs out of the conversation with Father and quickly kills him after End of the Line completes, they will still receive Banished from the Institute.
  • If having convinced Doctor Li to rejoin the Brotherhood through From Within, Doctor Watson will explain the quest details instead.
  • Depending on various quest choices, several named characters may be present during the fight:
  • Having completed Rockets' Red Glare for the Railroad before completing End of the Line, this quest is skipped entirely and one will progress immediately to Nuclear Family.
  • Fast traveling away from the airport, and then back to it, one will spawn in front of many heavily armed brotherhood soldiers.
  • This quest is the only known method (aside from console commands) to acquire Elder Maxson's BOS VII T-60f power armor with the unique BoS Elder paint scheme.
  • If the player is still friendly with the Brotherhood due to taking the available exploit during Mass Fusion, this quest will become much easier. Note that the Brotherhood will still become hostile, if the player is detected while destroying a generator.

Bugs

  • Icon pc.png Icon xboxone.png If the player killed all of the BoS members at the airport before destroying the last generator, they may not be able to complete the objective "Reach Liberty Prime". [verified]
  • Icon pc.png Icon ps4.png Icon xboxone.png Elder Maxson may not appear during the battle, making his unique items unobtainable. [verified]
  • Icon ps4.png Icon xboxone.png If fast traveling away from the airport after killing BoS members, their weapons and armor may respawn on return, including that of Quinlan, allowing for extra loot. This may even occur if the player uses the lift to get to the third generator. [verified]
  • Icon ps4.png Icon xboxone.png When asked to "work with members of the Institute," the quest will take the player to Evan (if Madison Li is killed or persuaded to join the BoS). They will be able to ask him "want to fill me in on what's happening", but he will never give them the information, but will instead repeat the same lines over and over again. [verified]
  • Icon pc.png Icon ps4.png Dialogue with Dr. Li and Rosalind Orman will sometimes be unable to finish, as T.S. Wallace often pushes the two away from each other.[verified]
  • [Platforms needed] Sometimes the synth carrying the virus will be stuck in a permanent downed state and the upload will get stuck at 0%. Simply killing this Synth will cause a new one to teleport in and allow the quest to continue. [verification needed]
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