Flyable Pelican and Phantom

The flyable Pelican and Phantom easter egg in Halo: Reach allows the player to pilot the Pelican and Phantom in the Halo: Reach campaign level New Alexandria. This was first revealed to exist to the players, after Bungie's campaign designer Dan Miller revealed that the Pelican is pilotable. The easter egg was figured out several hours after the release of the weekly update.

Walkthrough
First complete all objectives assigned until you are given the final objective to destroy the Shade turrets at the ONI Headquarters. Fly to the tower with Club Errera (It will have an orange rectangle on the top of the tower, look high) and look as if you are coming out. Approach the tower to the right of where you are and head to the right side of this building. There should be a hollow area with a ceiling but no floor whatsoever. If all the mission objectives prior to the ONI Headquarters are completed, a switch should be on the ceiling. The player must toggle it before the next step. This is possible on Solo and Co-Op.

Solo
The player must land their Falcon on the building's ledge, with its rotors balanced and touching the ledge so it remains in position. Then, using a jetpack, which is obtainable from Club Errera or the New Alexandria Hospital, fly up the the roof and trigger the switch. If done correctly and quickly enough, the Falcon should still be in place, and you should be able to return to it.

Co-op
First, one player stands on top of a Falcon, the pilot must then carefully hover into the hollow area in the back of the tower and adjust the altitude until they can activate the switch. This is best done if the player has a jetpack, which is obtainable during the Hospital and Nightclub segments of the mission.

After Activating the Switch
After activating the switch, you must fly through the oval ring in the tower that resembles the Shanghai World Financial Center. It may take several passes through the ring at a certain altitude to trigger the Easter Egg. Try aiming for about 3 quarters up in the ring.

At this point, if the player is in a Falcon or Banshee, they will be put into a Pelican or Phantom, respectively. The previous vehicle that they were in will then fall to the ground since the player is no longer piloting it.

Gameplay
Both vehicles are operated by using RB button to ascend and LB button to descend, with the default controls. The Phantom can boost by pressing LT button. Co-op players can ride in the back by holding action (although the indicator is not shown, it will still work). The chin gun of the Pelican can be operated by a player that holds action near it. They will have full motion and firing abilities but cannot see anything because of camera placement. The chin gun is the same as the Falcon's chin gun. Friendly Army troopers will automatically man the chin turret or ride in the back if the Pelican lands nearby. The Phantom's side plasma turrets where Unggoy usually man them can be manned by other players.

If the pilot exits the Pelican, it will disappear. Phantoms function almost identically, except that they are faster and the pilot cannot exit, except by committing suicide by flying too low. The Phantom can fly through buildings although the player will be killed instantly when this happens. If the player wishes to finish the level by themselves with the pelican they can simply push the shade turrets off the edge and not have to worry about their health.

Trivia

 * Note that if there are any passengers or gunners inside the Falcon during transformation, they will remain in the Falcon as it falls down. If the party leader is a passenger in the Falcon then they will get a Pelican first.
 * The player may also exit the normal barriers of the map while in a Pelican or Phantom and explore freely, even up to the Covenant CSS-Battlecruisers. If the player starts getting out too far, they will start seeing the effects of the Hall of Mirrors.
 * Please note that the Phantom is destructible. After taking large amounts of damage, it will explode. Unlike other vehicles in Reach, there is no way to tell how much strength the Phantom has left before exploding. The Pelican on the other hand is entirely indestructible.
 * The manner in which the Pelican flies seems to defy aerodynamics. To bank left, the right wing and its attached thruster tilts upward while the left wing and thruster tilts downward. The opposite is true when the Pelican banks right. In reality, these wing/thruster positions should have the opposite effect on the aircraft.
 * Projectiles fired from inside the cargo hold of the Pelican will travel straight outside through the Pelican.
 * If the Pelican is holding a passenger and makes too tight of a turn, the passenger will sometimes be booted from the seat.
 * If a Pelican looks down but is going backwards, passengers can exit but instead of exiting the Pelican, the passenger can actually move around in the Pelican however are prone to damage from the Pelican's movements.
 * Curiously, while there is no "affective" AI controlling the chin/"concussion" turret of the Pelican/Phantom respectively; they still turn around and point at threats or other players staring at them, but don't fire unless they are actually taken over by another player or trooper.
 * If you're a passenger and the pilot leaves, you will fall under the level's boundaries.
 * The altitude which triggers the change is 777 according to the Falcon's HUD; an obvious seven reference.

External

 * Youtube: Halo Reach Easter Egg : How To Drive The Pelican And Phantom (Co-op)
 * Youtube: Halo Reach - Flyable Pelican & Phantom Easter-egg Tutorial [New Alexandria ]