The HUD in combat

Each master mode changes the HUD. The speed and altitude boxes, the autopilot line and the red warnings are on every page; the rest changes. NAV is described in The HUD in NAV mode.

#The target box (all modes)

When the radar is locked:

• a small square sits on the target. It flashes while the lock is being made;
• if the target is outside the HUD, the square stays at the edge and a line from the centre points towards it;
• R (range, in NM or km) and VC (closure speed) show at the lower right;
• LOCK LOST flashes in the centre for 2 seconds if the lock breaks.

#BVR (2)

For long-range radar work. The pitch ladder and flight path marker are gone, leaving more room:

• Heading tape and a short horizon line.
• Scan zone: a dashed frame showing how wide and how tall the radar is scanning, with a tick for the antenna.
• Range scale on the right, the radar's range at the top. With a lock, a caret shows the target's range, and marks show the selected missile's launch zone: its longest range, the range it can't escape from, and its shortest range.
• LA (launch authorised) flashes under the centre when the selected missile can be fired.
• After a launch, T counts down the seconds until the missile reaches the target.
• The selected missile and how many you have, or NO MSL; and the radar state: RWS, TWS, ACQ or LOCK.

#WVR (3)

For close combat:

• An aiming circle in the centre, about 5.4° across.
• Where the close combat radar is looking, until it locks: two lines up from the nose for VS, a small circle for BORE, four corner marks for HUD.
• The flight path marker, and big G and α (angle of attack) readouts on the left: in a turning fight you watch these, not the speed.
• The seeker circle, LA, T, the selected missile and the radar state, as in BVR.

#GUN (5)

• Without a lock: a funnel, two curved walls showing where the shells go. Put the target between the walls, where its wingspan fills the gap.
• With a lock, once the target is within the shells' reach (about 2.5 seconds of flight): a lead computing sight: a cross in a ring, with an arc that shrinks as the range closes and the range in metres. SHOOT appears between 200 and 800 m. Put the cross on the target and fire.
• GUN and the rounds left (150 when full), the flight path marker, G and α.

Space fires the gun in GUN mode, in the air.

#GND (4)

A bombing sight: a pipper on a fall line from the flight path marker, with the height above the ground (AGL). There are no air-to-ground weapons yet, so it shows NO STORES.

#The missile seeker

With a heat-seeking missile selected (R-73, R-27T or R-27ET) in BVR or WVR:

1. The seeker looks straight ahead in a small cone, or, when the radar is locked, at the radar's target, as long as it is within the missile's launch limits (45° off the nose for the R-73, 50° for the R-27T and R-27ET).
2. When it sees a hot target, you hear a growl and a small circle on the HUD flashes.
3. After half a second on the same target it locks: a steady tone, and the circle stays steady with a ring round it.

It locks by itself; there is no key to uncage it. It can't tell friend from foe. Radar missiles have no seeker cue: they use the radar lock.