Multiple Guidance Modes
During flight, the Phoenix utilizes three different types of guidance in order to complete its task. Upon launch, the missile activates an onboard autopilot mode in order to fly a pre-determined flightpath.  At mid-range, the radar antenna of the missile is able to detect the F-14's radar energy, which is reflecting off of the target aircraft. This semi-active radar homing (SARH) mode provides the missile with mid-course corrections as it nears the target so that when the missile's own onboard radar takes over in the terminal stage, the target will be within the radar's constraints. This active radar homing mode takes place when the target is within range of the AIM-54's radar. At this point the Phoenix becomes a truly autonomous "fire-and-forget" weapon, following its own radar beam to the target. It requires nothing more from its launching aircraft. Time between launch and contact with the target can be as much as three minutes.
It has been widely reported that in addition to these guidance modes, the AIM-54 also features a home-on-jamming mode. It is speculated that the missile will travel most of the distance under autopilot mode until the target is suspected to be within range of the missile's radar. The radar then utilizes this special homing feature to seek out the source of the jamming energy. It is not known how successful this mode has been during trials. Given that it receives no mid-course corrections during flight suggests that there is a danger of the target aircraft maneuvering out of the onboard radar's coverage by the time the Phoenix covers the enormous distance. This fact may impose a limitation on the range of the missile, requiring the Tomcat to close the distance before launch.
In all cases, long-range Phoenix shots follow a parabolic trajectory. This has two advantages. First, there is an increase in range, as the missile does not have to waste energy maintaining level flight to the target following motor burnout. Second, the trajectory carries the missile out of the direct path of the Tomcat's radar, thus diminishing the interference between the F-14's initial radar waves and its reflective waves. Following this parabolic trajectory, the reflective waves are the stronger of the two signals.
One Missile, One Radar, One Aircraft
Rather than being a mere missile, the AIM-54 is actually part of a complex weapon system that marries a missile and radar together into a single unit. For this reason, the Phoenix cannot simply be mounted on another aircraft. The AWG-9/APG-71 fire control system allows a single F-14 to carry out a simultaneous attack against up to six separate targets while tracking a total of 24 contacts. The radar is capable of updating all of the missiles until such time as they can become autonomous, thus guiding themselves to the target in the terminal stage of flight.
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