Series 8 jetpack

The jetpack is a user-operated jet engine mounted on the back, solely used by the United Nations Space Command. Unlike the T-PACK, which is a maneuvering unit used on deep-space missions, the jetpack is used for atmospheric flight.

In Halo: Reach
A type of unidentified UNSC jetpack provides one of the seven Armor Abilities that are available in Halo: Reach.

Advantages
The Jetpack can be used for travel purposes, as they may bypass any need to walk up many different staircases, ramps, etc by flying up to the destination. Flying up high is also effective in combat; when an enemy has a short-ranged weapon, but the wielder of the Jetpack has a mid to long ranged-weapon, they can fly up high and be out of range of the enemy's weapon. Also, the Jetpack is a great tool for defending a flag carrier, because the flyer can swoop down on anyone trying to kill the flag carrier.

Disadvantages
If the player using the Jetpack flies too high without noting the fuel depleting, the player will fall from the height and be harmed, possibly dying upon impact. This can be countered by crouching just before impact, but requires precise timing.

The jetpack is still affected by the range of many weapons. The MA37 or other short-medium ranged weapons will still have the limited range and power, thus greatly reducing the attack power of the jetpack user.

Players using the jetpack are prone to being attacked by ground forces if they are unaware of their surroundings. Once shields are down and still in mid-air, there is almost always the chance that you will die. To prevent this, always be aware of your surroundings and motion tracker before you take off for long flights.

Players using the jetpack cannot move fast enough to avoid the Needler's lock on.

Trivia

 * The jetpack is the first propulsion equipment made available to the Spartan and Sangheili multiplayer models. The only similar equipment seen was the jetpacks on the Sangheili Rangers in Halo 2 and the Jiralhanae airborne troops in Halo Wars, Halo 3, and Halo 3: ODST.
 * In Halo: Reach, Weapons stored on your back when the Jetpack is equipped appear to be stored 'through' the thruster casing.