How do I get the Midnight Launch achievement?

The description for the achievement Midnight Launch is

In mission 2, get significant air in the warthog at midnight.

Is "midnight" supposed to refer to a location in the level, or do I actually have to do it at real life midnight local time? What exactly do I have to do to get it?

Solution 1:

The requirement is in fact "real life midnight", although lucky for you your XBox doesn't really know what time it is. To do so, the steps are:

1. Disconnect from Xbox live and go to your system setting to manually adjust time. Set it around 5-7 min before midnight.

2. Go to Rally point Alpha on Requiem (Mission 2).

3. Update: As Slenderman points out, the fastest/most reliable way to "jump" is simply to go off the cliff right next to where the Warthog spawns - unless of course you've got something against respawning... :).
   Check your time by pressing the XBox button as you progress, to keep track. You need to hit that jump in air at exactly midnight to get the achievement. Naturally this may prompt some trial and error, but its pretty easy to drive off a cliff - so hopefully you get it on the first try.
   If you want to go the conventional route, you can head for the big jump a little later in the level.

This video shows all the details: