F-15C HUD Operation

The Head-Up Display (HUD) is the primary flight and weapons reference in the F-15C. It combines attitude, navigation, air data, target, and weapon information so the pilot can keep looking outside during maneuvering and engagements.

Basic HUD Symbology

Many HUD symbols remain visible regardless of the selected master mode.

Symbol	Meaning
Heading scale	Magnetic heading tape. The center mark is the current aircraft heading.
Bank angle reference	Shows bank attitude at the top of the HUD.
Airspeed scale	Indicated airspeed in knots. Below low speed the tape may be blank.
Altitude scale	Barometric altitude in feet unless replaced by radio-altitude landing references.
Velocity vector	Actual flight path of the aircraft. During high AoA it may sit well below the nose reference.
Aircraft waterline	Aircraft longitudinal reference line.
Gun cross	Fixed reference aligned with the internal M61 cannon.
Pitch ladder	Pitch attitude in 5-degree increments, tied to aircraft roll attitude.
G readout	Current G and maximum recorded G.

Navigation Modes

Navigation Mode

In NAV mode the HUD gives steering to the selected route point.

Key cues:

• The heading scale includes a steering marker for the selected waypoint bearing.
• The lower-right mode line shows the current route point and NAV state, for example 1NAV.
• Distance to the selected point is shown in nautical miles, for example N 42.1.
• Estimated time to the selected point appears below the distance, computed from current groundspeed.

Instrument Landing System Navigation

ILSN mode adds approach steering and landing references to the normal navigation display.

During ILS approach, keep the flight path marker centered on the landing steering references. At low altitude, the right-side altitude reference changes to radio altitude. The AoA bracket helps hold the correct landing AoA; keep the velocity vector in the bracket rather than chasing pitch angle alone.

Gun Modes

The F-15C has two practical gun HUD presentations: one without radar lock and one with radar-directed gun solution.

Gun Without Radar Lock

Select the M61 cannon with no radar lock to display the no-lock gun sight. The HUD shows a fixed aiming reference and gun ammunition remaining in the lower-left data area.

Use this mode as a backup when radar ranging is unavailable. Place the target in the sight picture, fire short bursts, and correct from tracer impact.

Gun Director Sight

When the radar has a single target track and the gun is selected, the HUD enters Gun Director Sight (GDS) mode.

GDS adds:

• A Target Designator (TD) box around the locked target.
• A computed gun solution cue.
• Target range and closure information.
• Current weapon, ammunition, own Mach, and target Mach in the lower-left data area.

Fire only when the computed pipper and target relationship is stable. Long bursts waste ammunition and expose the aircraft to overshoot.

AIM-9 Sidewinder Modes

The AIM-9 seeker is infrared and can be used with or without radar support. It does not require radar illumination after launch.

Caged Mode

In caged mode the seeker is held near the aircraft boresight.

This is useful when selecting a specific target in a dense formation because the seeker will not freely wander outside the caged reference.

Uncaged / Scan Mode

Press the cage/uncage control to switch between caged and scan behavior.

The larger circle represents the seeker field of view. The smaller circle shows the current seeker line of sight. Once the seeker locks a heat source, the outer reference disappears and the seeker circle tracks the target within its gimbal limits.

Radar-Slaved AIM-9

With a radar lock, the AIM-9 seeker can be slaved toward the radar target.

The HUD shows the TD box, range scale, closure rate, and launch range cues. The missile still guides on infrared energy, but radar ranging improves the pilot's launch judgment.

AIM-7 Sparrow Modes

The AIM-7 is semi-active radar homing. The F-15C radar must illuminate the target until impact.

Flood Mode

Flood mode is a close-range backup mode for AIM-7 employment when a normal radar lock is unavailable.

The HUD displays a large flood circle. Keep the target inside that circle for the full missile flight so the missile can guide on reflected radar energy. Flood mode is not a fire-and-forget mode.

Single Target Track Mode

In STT, the HUD presents Sparrow launch steering.

Important cues:

• The TD box shows target position.
• The ASE circle shows allowable steering error.
• The target range scale shows current range and launch limits.
• The target aspect cue shows target heading relative to own aircraft.
• A launch cue appears when the target is in range and the steering solution is valid.

After launch, maintain lock until missile impact. Breaking lock deprives the missile of guidance.

AIM-120 AMRAAM Modes

The AIM-120 can receive mid-course support from the F-15C and then guide itself after its own active radar seeker turns on.

Visual Mode

Visual mode is a close-range active missile mode.

The HUD shows a visual acquisition circle and the VISUAL cue. A missile fired in this condition searches within its seeker volume. Use it only when the target is visually confirmed and the risk of guiding on the wrong aircraft is acceptable.

STT Before Launch

With a radar lock, the HUD provides normal AMRAAM launch steering and range cues before firing.

The display resembles AIM-7 STT but supports active missile timing. Confirm the target is inside valid launch parameters before release.

STT After Launch

After launch, the HUD displays missile time cues.

Typical cues include time to active seeker and estimated time to impact. Continue supporting the missile until it goes active when tactics allow; then crank, recommit, or defend based on threat state.

Auto-Acquisition Radar Modes

Auto-acquisition modes are intended for visual-range combat where manually slewing the radar cursor is too slow.

Boresight / BORE

BORE searches a narrow cone in front of the aircraft and locks the first target that enters the scan volume.

Vertical Scan

Vertical scan searches a tall, narrow volume above the nose. It is useful during high-G nose-up maneuvering when the bandit is crossing through the lift vector.