Hornet Radar Trainer — learn the AN/APG-73 radar
THROTTLE · LEFT HAND
TDC · DRAG TO SLEW
RADAR
STICK · RIGHT HAND
SENSOR CONTROL SWITCH
INSTRUCTOR MAP · TRUTH
START HERE
New to the Hornet's radar? Take the tutorial first. Each lesson then drills one skill in its own short scenario. When you're ready, free play sends you random encounters with an AWACS tasking, a clock and a score.
LESSONS
FREE PLAY
HOW THE APG-73 WORKS
The AN/APG-73 is the F/A-18C/D Hornet's X-band pulse-Doppler radar, an upgrade of the earlier APG-65 with much faster processing. Its antenna is a flat plate that the radar physically swings around to scan the sky. Everything below is how this trainer models it, from public sources and with simplified numbers.
The B-scope is not a map
The display plots azimuth (left–right of your nose, ±70°) across and range (0 at the bottom) up. Because every range gets the full width, contacts close to you are stretched along the bottom edge and the picture no longer matches the real geometry. A target on a collision course keeps the same azimuth and slides straight down. The instructor map shows the true picture beside the scope.
Scan volume and frame time
The antenna sweeps one horizontal line, a bar, then steps down and sweeps back. Azimuth width × bars is the volume searched, and the time to cover it all is the frame time. At about 80°/s (an estimate):
| Scan | Frame time |
|---|---|
| 140° × 4 bars | 7.0 s |
| 140° × 6 bars | 10.5 s |
| 80° × 2 bars | 2.0 s |
| 60° × 4 bars | 3.0 s |
| 20° × 2 bars | 0.5 s |
A bigger scan means an older picture: between looks the radar only knows where a target was. Search wide to find, then narrow the scan (or move its centre with the TDC) to follow.
Elevation and altitude coverage
The bars are stacked 1.2° apart around the antenna elevation you set with the wheel. That thin wedge gets taller with distance: the two numbers beside the cursor are the highest and lowest altitudes (thousands of feet) it covers at the cursor's range. A target at long range can easily fly above or below it. Check the numbers where you expect the bandit and roll the antenna until it paints.
PRF and the Doppler notch
A pulse-Doppler radar separates aircraft from the ground by their speed toward you. HI pulse-repetition frequency sees nose-on targets far away but struggles with anything moving away; MED sees every aspect at shorter range; INTL alternates the two bar by bar. Anything whose speed along your line of sight matches the ground's is thrown away with the clutter. A bandit flying 90° across your line of sight ("beaming") drops into that notch and disappears.
RWS, TWS and STT
RWS (Range While Search) paints raw hits, or bricks, that fade with age: good for finding things. TWS (Track While Scan) limits the scan so every contact is revisited within about 3 s and keeps a trackfile on each. You designate a primary target (L&S, ★) and a secondary (DT2, ◇). STT (Single Target Track) points the antenna at one target continuously: the best data, but that target's warning receiver knows it is locked, and the lock breaks if the target leaves the ±70° gimbal limit or stays in the notch for more than 3 s.
RWS keeps trackfiles too, just hidden. With Latent TWS (on by default, as in DCS) the cursor on a brick shows its trackfile, so the first TDC press designates it (★) and the second one locks. Pushing the castle switch toward the radar display (Fast Acquisition) locks whatever is under the cursor in one press.
ACM: close-in auto-acquisition
Inside 10 nm there is no time to hunt for bricks. Push the castle switch forward for Boresight (a 3.3° beam down the nose). Inside ACM, castle left gives Wide acquisition (a 60°-wide box) and aft gives Vertical acquisition (a tall column above the nose, for turning fights). Each mode locks the first aircraft it finds in its box.
Which mode, and when
- RWS: searching. Wide scan, long range, nobody knows you are looking yet. Use it to find contacts and to check a wide piece of sky. Bricks are only raw hits, so you get little data on them.
- TWS: building the picture. Once there are several contacts, or you want to watch where they are going without committing. You get heading and speed on each, at the price of a narrower scan. Designate L&S for the one you care about and DT2 for the next.
- STT: committing. You have decided on one target and want the best data, for example to shoot or to run NCTR. It is also the loudest choice: the target's warning receiver sees the lock, and the rest of the picture stops updating while you stare at one aircraft.
- ACM: the visual fight. Inside about 10 nm, when hunting for a contact is too slow. Pick Boresight if the target is on the nose, Wide if it is off to the side, Vertical in a turning fight.
A typical flow: RWS to find, TWS to sort, STT to shoot. Drop to ACM only if the merge happens.
IFF, NCTR and HAFU symbols
Pressing the castle switch interrogates the aircraft under the cursor. A friendly's transponder replies; silence makes a contact ambiguous, not hostile. In STT, NCTR (non-cooperative target recognition) can identify the engine type of a nose-on target inside about 25 nm; an ambiguous contact with a hostile type becomes hostile. The symbols show identity by shape:
- Unknown
- Ambiguous
- Friendly
- Hostile
Scan rate, detection ranges, the NCTR limits and some timings are estimates: the real figures are not public. See Sources below.
CONTROLS REFERENCE
Pushbuttons are numbered clockwise from the bottom of the left column: PB1–5 up the left side, PB6–10 across the top, PB11–15 down the right side, PB16–20 back along the bottom (PB18 is the middle one).
| PB | RWS | TWS | STT | ACM | DATA |
|---|---|---|---|---|---|
| PB1 | PRF (MED / HI / INTL) | PRF | PRF | — | — |
| PB5 | RWS → TWS | TWS → RWS | RTS (back to search) | Shows the ACM sub-mode | — |
| PB6 | Bars 1/2/4/6 | Bars 2/4/6 | Bar number only | — | — |
| PB7 | SIL (silent) | SIL | SIL | SIL | — |
| PB8 | ERASE bricks | — | — | — | — |
| PB10 | — | — | TWS (keep target as ★) | — | AGE 2–32 s |
| PB11 / 12 | Range ↑ / ↓ | Range ↑ / ↓ | — | — | — |
| PB13 | — | AUTO / MAN centring | — | — | — |
| PB14 | RSET (clear ★ ◇) | RSET | RSET | — | — |
| PB15 | NCTR on/off | NCTR | NCTR | — | LTWS on/off |
| PB16 | DATA page | DATA | DATA | — | DATA (back) |
| PB18 | MENU | MENU | MENU | MENU | MENU |
| PB19 | Azimuth 20–140° | Azimuth (TWS limits) | — | — | — |
Every control takes one key and one joystick or HOTAS input. Click a slot, then press the key, or press the joystick button, or push the axis or hat switch and let it go. Esc cancels, Backspace clears the slot.
| Control | Keyboard | Joystick / HOTAS | What it does |
|---|---|---|---|
| TDC up | Move the cursor. Push it into the top or bottom edge to change range, a side edge to change azimuth. | ||
| TDC down | |||
| TDC left | |||
| TDC right | |||
| TDC depress | Designate: trackfile (or, with LTWS, a brick) → ★, then ◇; ★ → lock; brick with LTWS off → lock; empty space → move the scan centre | ||
| Antenna elevation up | Raise all bars together | ||
| Antenna elevation down | Lower all bars together | ||
| Castle forward | ACM Boresight | ||
| Castle aft | In ACM: Vertical acquisition | ||
| Castle left | In ACM: Wide acquisition | ||
| Castle right | Take the TDC (the diamond); then lock what is under the cursor, else the ★, else the #1 trackfile (AACQ) | ||
| Castle press | IFF interrogation of the contact under the cursor | ||
| Undesignate | Break lock / leave ACM; in RWS and TWS: make #1 the ★, swap ★ ◇, or step ★ through the ranks |
| Control | Keyboard | Joystick / HOTAS | What it does |
|---|---|---|---|
| Turn left | |||
| Turn right | |||
| Fine turn | Hold while turning for small corrections | ||
| Nose down | Descend | ||
| Nose up | Climb | ||
| Faster | |||
| Slower | |||
| Pause | |||
| Instructor map | On / off |
Bindings are saved in this browser. A joystick shows up once you press one of its buttons on this page, and only over HTTPS or on localhost. Keys work while the cockpit fills at least half the screen, so Space still scrolls the page down here. Every on-screen control can also be clicked or tapped.
COMING FROM DCS
The trainer follows the DCS Hornet's radar controls where it can. These are the questions new DCS Hornet pilots ask most.
My cursor won't move.
The TDC only works on the display that owns it, marked by a diamond in the top-right corner. Push the castle switch toward the radar display (right in DCS, where the radar sits on the right DDI; L here) to take it.
I press the TDC on a brick and it doesn't lock.
That is Latent TWS, on by default in DCS: the cursor on a brick shows its trackfile, the first press makes it the L&S (★) and the second locks it. Castle toward the radar (Fast Acquisition) locks in one press. Turn LTWS off on the DATA page (PB15) if you want one press to lock a brick.
AWACS or the SA page shows a contact, but my radar shows nothing.
Almost always the antenna elevation. Put the cursor at the contact's range, read the two altitude numbers beside it and roll the antenna until the contact's altitude sits between them. Then check the range scale and the azimuth width. The lesson "From an AWACS call to a lock" drills this.
The radar shows nothing at all.
Check the RADAR knob is in OPR (STBY shows a cross in the lower-left corner) and SIL is not boxed. Then elevation, as above. A target flying across your nose can hide in the Doppler notch; one flying away is hard to see in HI PRF.
My lock keeps breaking.
The antenna can only look 70° either side of the nose, so hard turns lose it. A beaming target drops into the notch: MEM shows for about 3 s, then the lock breaks. It also breaks out of range.
Should I lock (STT) or use TWS?
STT gives the best data on one target, but its warning receiver hears the lock and the rest of your picture freezes. TWS tracks several contacts without telling them. See "Which mode, and when" above.
Undesignate does something different each time.
It depends on the state. In STT or ACM it returns to search. In RWS or TWS with nothing designated it makes the #1 trackfile the ★. With a ★ and a ◇ it swaps them; with only a ★ it steps the ★ through the ranks.
What does the trainer leave out?
Weapons (the AIM-120 and its launch zone are planned next), datalink and the SA and Az/El pages, the VS, RAID and Spotlight modes, and bandits that react to your lock. The radar numbers are simplified public estimates.
GLOSSARY
- AACQ
- Automatic Acquisition: castle toward the radar display locks the contact under the cursor (Fast Acq), else the L&S, else the #1 trackfile.
- ACM
- Air Combat Maneuvering modes: automatic lock-on inside 10 nm (Boresight, Vertical, Wide acquisition).
- Bar
- One horizontal sweep of the antenna. Several bars stacked 1.2° apart make up the scan.
- B-scope
- The display format: azimuth across, range up. Not a map: close contacts are stretched sideways.
- BRAA
- Bearing, Range, Altitude, Aspect: how a controller (AWACS) calls where a contact is.
- Brick
- A raw radar hit in RWS: where a target was when the beam passed it. Fades with age.
- DDI
- Digital Display Indicator: the Hornet cockpit screen with 20 pushbuttons around it.
- DT2
- Secondary designated target (◇) in TWS.
- Frame
- One complete pass over the whole scan volume. Frame time = how old the picture can get.
- HAFU
- Hostile / Ambiguous / Friendly / Unknown: the trackfile symbol whose shape shows identity.
- HOTAS
- Hands On Throttle And Stick: flying the radar without letting go of the controls.
- IFF
- Identification Friend or Foe: an interrogation that a friendly transponder answers.
- L&S
- Launch & Steering target (★): the primary designated target.
- LTWS
- Latent TWS: in RWS, putting the cursor on a brick shows its trackfile, which you can then designate. On by default in DCS.
- MEM
- Memory: the radar coasting on its last estimate after losing the target for a moment in STT.
- NCTR
- Non-Cooperative Target Recognition: identifying an aircraft type from its engines, nose-on and in STT.
- Notch
- The Doppler blind spot: targets moving across your line of sight look like ground clutter and are filtered out.
- PRF
- Pulse Repetition Frequency: HI for long range nose-on, MED for all aspects, INTL for both.
- RWS
- Range While Search: the basic search mode, showing bricks.
- STT
- Single Target Track: a lock on one target. Best data; the target knows.
- TDC
- Throttle Designator Controller: the thumb control that moves the cursor and designates.
- TDC priority
- Which display the TDC is working on, marked by a diamond in its corner. The castle switch hands it over.
- TWS
- Track While Scan: search that keeps trackfiles on several targets at once.