Mind the Gap Achievement in Halo: The Master Chief Collection

This mission-specific achievement is obtained in the following mission: Tvaso Highway. Additionally, while this can technically be done in a Solo playthrough of the mission, it is highly recommended to work on this achievement in four-player Co-Op play. Once you have three other Co-Op partners and are in the Campaign Lobby, go ahead and turn on the aforementioned skulls.

After the lobby has been set up, start the mission. Once all the players present gain control of their characters, break off into two groups and grab both Warthogs in the basement hanger. Then, start rolling out into the valleys outside. Along the way, you can find three more overturned Warthogs, two of which the passengers should grab as their own. As a note, you don't necessarily need to fight against the Covenant within these valleys, though it might be necessary to jump out of the Warthogs for a few minutes and lay waste to the Jackal Snipers, Turrets, and Brute Captains/Chieftains so that the Warthogs stay intact.

Once all four players have their own Warthog, continue through the mission until you reach the area that houses two Choppers, half a dozen Brutes, and an energy barrier that blocks vehicular movement through the tunneled highway. In this area, everyone should get out of their Warthogs and work together in clearing out the Covenant threat. Once that's done, head through the energy barrier on foot, destroy the energy source and get ready to lay waste on the Drones that spawn inside the tunnel. After they have been eliminated, head backwards to the main valley and check the small buildings. One of them has a Gravity Lift which is necessary for this achievement.

With the Gravity Lift in possession, all four players should now hop back into their Warthogs and head through the tunnel. Continue to drive down the highway and accelerate over the first small jump in the road. Just ahead, you should see a few concrete barriers blocking passage to the rest of the highway. At this point, everyone should line their Warthogs up in a straight line and the first player should drop the Gravity Lift in front of the barriers. This player should then quickly get back in the Warthog and now all four players should proceed to drive forwards through the Gravity Lift. If angled correctly, the lift will shoot all the players up in the air as they drive over it and launch they'll be launched forward over the gap in the highway. Once the fourth player has safely landed on the highway, the achievement will unlock for all four players in the game.