The heads up display (HUD) is a display of weapon selection for any secondary weapons (green square in upper left side that indicates the current selected weapon with an icon of that weapon and the ammo in it before becoming empty and must wait for ammo to regenerate before it can be used again), the health bar (divided in 4 sections, health will regenerate according to difficulty to the end of that section and will not regenerate a section of health if the health surpasses the end of that section), objective meter (a bar that indicates that there is a certain amount of time you have left to complete an objective before mission failure or how much damage the objective can take before it is destroyed), mission and bonus mission

Th (4)

objective (tan rectangle that pops up when an objective has been given, completed, or failed) and will show any enemy planes that are targeting you which are represented by an arrow with corresponding color for type of plane (unidentified planes have clear arrows with a red outline that disappears after a second of appearing, targeted planes have yellow arrows with a red outline that points in the direction of the target, and an untargeted plane will have a red arrow that disappears after a second of appearing). There is also a small red icon that says "ALT" that will warn you if you are critically low to the ground to the point that any descending at that point will cause the plane to crash (instant death).