Alien Aircraft, also known as Manta Rays or simply Mantas are large creatures used as living aircraft by the Xenian 'Military' during the Black Mesa incident, both around the Black Mesa compound and Xen.
There are two types of Alien Aircraft. One type, encountered in the first map of the Half-Life chapter Interloper, has a pointed head and a single tail. The other, which is encountered in all Half-Life games, has a cleft head and two tails. The outer hides of both are impervious to damage even from the RPG.
These aliens are capable of reaching the speed of a military fighter jet, evidenced by the shock waves created as they zoom past; In addition, the Alien Aircraft are capable of generating an orange beam of energy from their similarly colored underside, most notably seen in the beginning of Opposing Force, where several crafts take down US Ospreys Goose 7 and 3 using the same beam.
It is yet unknown how this ray-shaped Alien Aircraft is capable of hovering above ground, emitting light and generating high-voltage electricity beams, however, their seemingly intelligent behavior and quick reactions suggest that these alien flying machines are in fact living beings with a somewhat sophisticated predator-like intelligence. They seem to ignore living beings which are smaller than them, they don't even react to being attacked, which suggests that the Alien Aircrafts' outer layer is impenetrable for most types of weapons, even high-powered energy blasts will leave them unharmed. Another theory is that if these Aircrafts are living beings, they are capable of self-healing and regenerating themselves.
Despite the Alien Aircraft's' peaceful nature, they can be unimaginably dangerous in battle. The single-tailed specimens are capable of emitting a highly destructive energy beam from their broadside, killing a living creature instantly, or destroying heavily armored machines and structures (the destruction of the two Escort Carriers are the most notable examples). The downside is, however, the alien aircraft must re-charge itself from time to time between these energy beam attacks, and it also requires precise aiming as well. Having no other attacking capabilities, the Alien Aircraft's tough outer shell and high agility is essential for them to survive.
The twin-tailed variant of the alien aircraft is seemingly unarmed, though it's just as quick and heavily armored as the single-tailed counterpart.
Alien Aircrafts are also capable of vaporizing into thin air and re-appear a more distant location using the same method, although this ability was only seen being used on Xen. It is noticable alien aircraft don't use the same method of teleporting as other Xen creatures.
The double-tailed Alien Aircraft is used widely by other Xen aliens, usually for transporting Alien Grunts, somewhat imitating deployment of US Marines from Ospreys, as well as the troop transport structures commonly carried by Combine Dropships. However, as they pass by, it is notable that these soldiers appear through violet flashes from its skin, suggesting that it merely teleports them from other places.
Behind the scenes
As it is only named in the Half-Life Prima Guide that few players own, the Alien Aircraft is commonly known among players as the "Manta Ray", due to its similarities with the fish of the same name. "Flyer" is also sometimes used, as it is its entity name in Decay.
- In Half-Life: Decay, a double-tailed Alien Aircraft serves as the game's final boss, and bears a couple slight differences to its counterparts. Specifically, A scarlet red underside with a slit down the middle, and faint yellow stripes on its outer skin.
- This particular Alien Aircraft appearance is the only one that can be destroyed by rockets. Its purpose is to destroy the "Displacement beacon" set up by Dr. Richard Keller, meant to create a "Resonance reversal".
- The Alien Aircrafts that destroy "Goose 3" and "7" are also colored differently than their normal appearances.