Care Package

Care Package is a multiplayer killstreak reward in Call of Duty: Modern Warfare 2. After achieving a killstreak of 4, or 3 with the Hardline perk, the player will be given a special Smoke Grenade that emits red smoke. A helicopter drops a large crate at the point designated by the smoke. This crate can contain a full ammo restock, or any killstreak except Emergency Airdrop, a Tactical Nuke, or another Care Package. This helicopter can be shot down before dropping the care package, although it's relatively difficult to do so.

There were initially two major glitches with the Care Package, Sentry Gun, and Emergency Airdrop. While holding the smoke grenade, players would receive a large increase in movement speed, which was often combined with continuously call in

Advantages and Disadvantages
Care Packages can be quite advantageous in that they have a chance of giving the player a killstreak reward that otherwise would take more kills to earn. However, they will often contain lower killstreak rewards or ammo resupplies, making the care package a gamble.

However, any player, including enemies, can take the care package. The player that calls the care package in can capture it almost instantaneously, but any other player will take five seconds to pick it up. If an enemy captures a powerful killstreak reward, the results can be disastrous.

The care package itself can also be deadly. If it lands on top of any player or rolls onto them after touching down, they will be killed, although it's rare to get a kill that way and hard to use tactically. Care packages also bounce of walls and various surfaces when dropped, and can kill you if badly thrown.

Caution must be exercised when throwing the smoke grenade to ensure that the care package lands in a place where it is both reachable and safe to pick up, as the package can be dropped outside the map or on top of inaccessible buildings, considering the fact that the game doesn't consider the actual location where it drops the package. Also, using packages in open areas or contested areas is unadvised, as enemies can easily kill you and steal it.

Care Packages appear on the radar. Both friendly and enemy care package marker's smoke is red. If the helicopter is shot down before the drop zone it will fall out where ever it is shot down, however shooting down Little Bird helicopters is very hard.

You can kill an enemy with the care package marker with direct impact. Any kills gotten with whatever the Care Package gives to the player do not count towards a player's killstreak, except if the care package falls on a player in which case that kill counts towards whoever called in the care package.

Content Probabilities
The probability of any given item is as follows (according to PC code):
 * 14.78% - UAV
 * 14.78% - Ammo
 * 13.04% - Counter-UAV
 * 10.43% - Sentry Gun
 * 10.43% - Predator Missile
 * 9.57% - Precision Airstrike
 * 6.09% - Harrier Airstrike
 * 6.09% - Attack Helicopter
 * 4.35% - Pave Low
 * 4.35% - Stealth Bomber
 * 2.61% - Chopper Gunner
 * 2.61% - AC-130
 * 0.87% - EMP
 * 0% - Tactical Nuke 
 * 0% - Care Package 
 * 0% - Emergency Airdrop 

Tips

 * Be careful while picking up Care Packages, as enemies will often look for easy kills and a free killstreak reward when Care Packages are called in.
 * Consider leaving unwanted crates as bait for ambushes.
 * Care Packages can smash through glass, which is useful when indoors.
 * Look up before throwing the care package marker to make sure there is nothing above the marker that the package will get stuck on, especially on the map, "Underpass."
 * If a UAV or Counter-UAV is dropped, leave it for a teammate as this will award the "Share Package" XP bonus while having the exact same effect, as UAVs and Counter-UAVs apply to the whole team.
 * It's often a good idea to wait until there are teammates nearby to drop a Care Package, as they have a chance to get it before the enemy in the event that you are killed.
 * Be careful holding on to Care Package Markers. It can be beneficial to carry them until especially needed, but can also be harmful; the game can end before the Care Package is retreived, or before the awarded Killstreak is used to its full potential. Keep an eye on the scores and the time. Make full use of every Care Package and Killstreak. They can mean the difference between winning and losing a game.

Trivia

 * Infinity Ward has confirmed that it is impossible to get a Tactical Nuke in a care package.
 * Any kills scored though the reward gained from a Care Package will not count towards earning additional killstreaks (with the exception of getting a sentry gun in a care package). However the Care package can add kills towards killstreaks if it crushes a hostile player by landing on him.
 * Though a difficult feat due to the small amount of time it spends on the map, the care package delivery helicopter can be shot down. However, no points are awarded to the player that manages to do so, but will count toward challenges that involve destroying killstreaks (I.E. Cold Blooded Pro). Care package delivery helicopters can also be shot down before they drop their load. This feat is most easily pulled off if the player positions himself on a high area with a full 360 degree, unobstructed view of the skies. The player will need to pay close attention to his map and respond quickly to the incoming delivery helicopter. If lucky, the delivery helicopter will take a longer route than normal and cross over more of the map than necessary before dropping off its care package. This gives the player an opportunity to shoot it down. When shot down with the care package still attached, the care package detaches from the helicopter and falls down. No points are awarded for this either. Having to concentrate on this one task ruins your game however, and since there are no awards it is usually never attempted by anyone. However if an EMP is detonated while the Little Bird is in the air it will be destroyed.
 * Like Tactical Insertion, the player can choose to forgo using the package, and instead use it as bait for ambushing an unsuspecting enemy. However, the player may be killed by the intended victim(s), who may then take the package for themselves, or even teammates might steal the package.
 * A player can be killed if the care package hits them when coming down.
 * The radius from which players can open a care package actually forms a sphere - allowing some lucky players to capture a care package from underneath it. This can commonly be done in maps like Favela, where Care Packages can land on roofs or other structures.
 * It is generally inadvisable to use the Care Package killstreak on Hardcore game types, as particularly malicious teammates will simply kill the player and steal the package (Unless playing on one of the "Ricochet" game types). This is even more applicable towards Emergency Airdrops for the same reason.
 * A player cannot survive being crushed with a package even if the care package hits their riot shield.
 * It is generally frowned upon attempting to take a teammates care package unless they are killed before capturing it.
 * There is a nice tactic for safely obtaining the Care Package. When the player throws a marker, he or she should deploy a Tactical Insertion near it. Thus, if they are killed by the enemy, they will respawn near the Package, with high chances of killing a foe and obtaining ammo or killstreak.
 * There is a Challenge to be completed when later unlocked under Finishing Moves to drop a care package on a hostile and winning the match as per last kill.
 * If one knifes an opponent while the care package canister is in hand, the knife will still knife, but make a different noise, noticeably softer than the normal knife sound. It sounds very much like the melee sound from Call of Duty 2. (NOTE: This has been patched. It used to increase running speed and you were generally harder to hit. Now you actually use your knife, and you run your normal speed).
 * On gametypes that have rounds, like Capture the Flag, Search and Destroy and Demolition remember to watch the timer to see if there is enough time for you to retrieve your care package. If you do not have enough time save it till the next round.
 * When a player knifes while holding a care package, they bend over in a strange way.
 * The killstreak icon for the Care Package sees it dropping down with a parachute attached. However in game the Little Bird drops it straight down with no parachute. This may be because the Little Bird was meant to be a different killstreak and the Care Package could have been dropped with a parachute. Or another theory is that there was a Little Bird and a parachute but the game developers decided it would take too long to reach the ground so they removed the parachute.
 * The challenge "Droppin' Crates" (Obtain the Game Winning Kill by dropping a crate on an enemy) is a possible reference to the Disturbed song "Droppin' Plates"
 * There is a glitch where a Care Package cannot be called in. (Confirmed on PC)
 * While taking the care package, if you jump and start to take it (better of with a teammate because they take a little longer) you will float. When you finish obtaining it, you fall back like normal.
 * An easy way the get the challenge "Droppin' Crates" is to find a sniper who is laying down and camping, and simply call in the crate on his location.