New Alexandria is the ninth level in Halo: Reach and the eighth playable one. This is one of the only levels in the Halo Games that has a unique structure. There are three main objectives which may be assigned to the player in any order, and then their is minor objectives between these are randomly selected from a larger pool every time the mission is played. This means the first play through and the second play through will most definitely be different. The level requires Noble Six to take out Communication Jammers.
This walkthrough will be relative to my play through. Although there will be some things the same.
 Fly by Night
In this level no matter what you will take out three jammers. The first jammer for me was the Jammer in the New Alexandria hospital. While flying there shot any Banshees that shot you, if they are not shotting you, you can leave them. Near the hospital on the other building there is a Shade, take it out and land the Falcon. Once inside, head down the ramps killing any enemies in your way. There are many random armour abilities scattered through the ramps, and located next to the Drop Shield and Armour Lock is a Shotgun. Continue head downstairs and you will find DMR ammo.
Once at the bottom, kill all the Brutes in your way. If you can try and take out the Engineer as they will provide shields for the Brutes. Once you get to the end, you will deactivate the Jammer and some Elites will appear. Kill them on the way back to the Falcon. The next objective is random, for me it is to defend marines from Jackal Snipers. Once you do your random objective, you will once again have to destroy a jammer. This one for me is located at the Tower or Club Errera. Once at the tower, kill the platform from the Shades, Brutes and Skirmishers, but always watch your back for Banshees. Once they are dead hop out and head into the tower. Once inside clear one side of Hunters and then deactivate the jammer. Then head down the other side and kill the remaining Hunters. Once again a random objective will happen, complete it. The last remaining jammer is in the SinoViet HM Center. Once again, kill the Shades on the landing pad. It is possible to get the Falcon in the building if you want to take the enemies out easy. Once they are dead head into the elevator. Once at the top head left and grab some shot gun ammo to the left as well as active Camouflage. Activate the Jammer, once that happens a lot of Drones will appear the Active Camou comes in handy when you are beginning to be overwhelmed. Really you can just run out and not kill them.
 Emergency Missions
This missions are randomly selected and are done between the Jammer missions.
 Last One Out…Turn Out the Lights
Head over to the tower now. Take out the shades, this is an easy section. Once the Shade turrets are destroyed, land at the platform.