Merge pull request #1096 from Rohilalala/fix/military-sticky-track

fix(military): hold the last track and speed when a poll omits them

changelog.d/1096-military-hold-track-speed.md

@@ -0,0 +1,3 @@
+- Military aircraft keep their last heading and speed when an adsb.lol row omits
+  `track` or `gs`, instead of turning north and stopping; a grounded row without
+  a speed still reads 0 (Aditya, @Rohilalala, #1096).

docs/CURRENT-STATE.md

@@ -584,7 +584,9 @@ pinning, first-position grace, source time and sea-surface placement are unchang
 
 Military flights also separate portable records and source acquisition from
 Cesium snapshot application. The metadata owner retains aviation feet, source
-fix times, sticky fields and partial-feed retention. Rendering retains ground
+fix times, sticky fields and partial-feed retention. A row without track or
+speed holds the last known value, as civil records do; a grounded row without
+speed reads 0. Rendering retains ground
 model ownership, motion history, military registration and tracking cleanup.
 
 Civil flights separate source acquisition, portable record reconciliation and

src/layers/military/records.js

@@ -39,8 +39,6 @@ export class MilitaryFlightRecords {
           ? prevMeta.altitudeFt * 0.3048
           : 0
         : 3048);
-    const track = aircraft.courseDeg || 0;
-    const speedMps = aircraft.speedMps ?? 0;
     const verticalRateMps = aircraft.verticalRateMps;
     const callsign = aircraft.callsign;
     const type = aircraft.typeCode;
@@ -148,8 +146,15 @@ export class MilitaryFlightRecords {
       // altitudeFt/baro).
       geoAltitudeM,
       renderAltitudeM,
-      speedMps: stickyNumber(speedMps, prevMeta?.speedMps, null),
+      // A poll that omits track/speed holds the last values, like the civil
-      track: stickyNumber(track, prevMeta?.track, null),
+      // records; 0 only until one is known. A grounded row without a speed
+      // reads 0, so a parked plane never coasts at its landing speed.
+      speedMps: stickyNumber(
+        aircraft.speedMps,
+        onGround ? 0 : prevMeta?.speedMps,
+        0,
+      ),
+      track: stickyNumber(aircraft.courseDeg, prevMeta?.track, 0),
       // Analyst seam (additive): sticky like the other kinematics.
       verticalRateMps: stickyNumber(
         verticalRateMps,

src/layers/military/records.test.mjs

@@ -114,3 +114,39 @@ test('military emergency status follows the latest poll instead of sticking', ()
   );
   assert.equal(next.meta.emergency, null);
 });
+
+test('military records hold the last track and speed when a poll omits them', () => {
+  const records = store();
+  records.receive(observation({ courseDeg: 270, speedMps: 200 }), context());
+  const missing = records.receive(
+    observation({ courseDeg: null, speedMps: null }),
+    context(),
+  );
+  assert.equal(missing.meta.track, 270);
+  assert.equal(missing.meta.speedMps, 200);
+  const north = records.receive(
+    observation({ courseDeg: 0, speedMps: 0 }),
+    context(),
+  );
+  assert.equal(north.meta.track, 0);
+  assert.equal(north.meta.speedMps, 0);
+  const unseen = store().receive(
+    observation({ courseDeg: undefined, speedMps: undefined }),
+    context(),
+  );
+  assert.equal(unseen.meta.track, 0);
+  assert.equal(unseen.meta.speedMps, 0);
+  const landing = store();
+  landing.receive(observation({ courseDeg: 90, speedMps: 70 }), context());
+  const parked = landing.receive(
+    observation({
+      onGround: true,
+      baroAltitudeM: null,
+      courseDeg: null,
+      speedMps: null,
+    }),
+    context(),
+  );
+  assert.equal(parked.meta.speedMps, 0);
+  assert.equal(parked.meta.track, 90);
+});