diff --git a/drb-c2-core/app/routers/telemetry.py b/drb-c2-core/app/routers/telemetry.py
index 8b9bc20..e46ef76 100644
--- a/drb-c2-core/app/routers/telemetry.py
+++ b/drb-c2-core/app/routers/telemetry.py
@@ -1,5 +1,6 @@
-from datetime import datetime, timezone
-from typing import List, Optional
+import asyncio
+from datetime import datetime, timedelta, timezone
+from typing import Dict, List, Optional, Tuple
 
 from fastapi import APIRouter, Depends, HTTPException
 from pydantic import BaseModel
@@ -10,6 +11,20 @@ from app.internal.logger import logger
 
 router = APIRouter(prefix="/telemetry", tags=["telemetry"])
 
+# Flight trail: every position change is also written to
+# aircraft/{icao}/positions/{epoch_ms}, so clicking an aircraft on the map can
+# draw the path heard so far. Points expire via a Firestore TTL policy on
+# expire_at (infra/firestore/firestore.indexes.json fieldOverrides).
+POSITIONS_SUBCOLLECTION = "positions"
+POSITION_TTL = timedelta(hours=24)
+
+# Last position written per icao, so an aircraft reported unchanged across
+# several 10s uploads (readsb holds a position until a new one decodes)
+# doesn't get a duplicate point each time. Process-local and lossy by design:
+# after a restart the worst case is one duplicate point per aircraft.
+_last_position: Dict[str, Tuple[float, float]] = {}
+_LAST_POSITION_MAX = 5000
+
 
 class AircraftReport(BaseModel):
     icao: str
@@ -32,8 +47,8 @@ async def upload_adsb(
 ):
     """
     Node-initiated: a second-SDR ADS-B decoder (node-26#9) periodically posts
-    its current aircraft snapshot here. One doc per icao, last-seen-wins —
-    this is a live-map overlay, not a flight history.
+    its current aircraft snapshot here. One doc per icao, last-seen-wins,
+    plus one trail point per position change (see POSITIONS_SUBCOLLECTION).
     """
     node_id = decoded.get("node_id")
     if not node_id:
@@ -43,7 +58,11 @@ async def upload_adsb(
     org_id = node.get("org_id") if node else None
     now = datetime.now(timezone.utc).isoformat()
 
+    expire_at = datetime.now(timezone.utc) + POSITION_TTL
+    epoch_ms = int(datetime.now(timezone.utc).timestamp() * 1000)
+
     writes = []
+    trail = []
     for ac in body.aircraft:
         if not ac.icao:
             continue
@@ -62,12 +81,33 @@ async def upload_adsb(
             doc["org_id"] = org_id
         writes.append(("aircraft", ac.icao, doc))
 
-    for collection, doc_id, doc in writes:
+        if ac.lat is None or ac.lon is None:
+            continue
+        pos = (ac.lat, ac.lon)
+        if _last_position.get(ac.icao) == pos:
+            continue
+        _last_position[ac.icao] = pos
+        point = {
+            "lat": ac.lat,
+            "lon": ac.lon,
+            "altitude_ft": ac.altitude_ft,
+            "t": now,
+            "expire_at": expire_at,
+        }
+        trail.append((f"aircraft/{ac.icao}/{POSITIONS_SUBCOLLECTION}", str(epoch_ms), point))
+
+    if len(_last_position) > _LAST_POSITION_MAX:
+        _last_position.clear()
+
+    async def _write(collection: str, doc_id: str, doc: dict) -> None:
         try:
             await fstore.doc_set(collection, doc_id, doc, merge=True)
         except Exception as e:
             logger.warning(f"Failed to upsert {collection}/{doc_id} from node {node_id}: {e}")
 
+    # Concurrent: a busy sky is dozens of aircraft, two writes each, every 10s.
+    await asyncio.gather(*(_write(*w) for w in writes + trail))
+
     return {"ok": True, "count": len(writes)}
 
 
diff --git a/drb-c2-core/tests/test_telemetry.py b/drb-c2-core/tests/test_telemetry.py
index 3854d12..c3852a2 100644
--- a/drb-c2-core/tests/test_telemetry.py
+++ b/drb-c2-core/tests/test_telemetry.py
@@ -24,6 +24,11 @@ def _override(decoded: dict):
 
 def teardown_function():
     app.dependency_overrides.pop(require_node_service_or_firebase_token, None)
+    telemetry._last_position.clear()
+
+
+def _writes_to(mock_set, collection_prefix: str):
+    return [c for c in mock_set.await_args_list if c.args[0].startswith(collection_prefix)]
 
 
 def test_service_token_without_node_id_is_rejected():
@@ -41,8 +46,9 @@ def test_node_upload_upserts_and_stamps_org_id():
         })
     assert resp.status_code == 200
     assert resp.json() == {"ok": True, "count": 1}
-    mock_set.assert_awaited_once()
-    (collection, doc_id, doc), kwargs = mock_set.await_args
+    snapshot = [c for c in mock_set.await_args_list if c.args[0] == "aircraft"]
+    assert len(snapshot) == 1
+    (collection, doc_id, doc), kwargs = snapshot[0]
     assert collection == "aircraft"
     assert doc_id == "A1B2C3"
     assert doc["node_id"] == "node-1"
@@ -92,3 +98,38 @@ def test_ais_node_upload_skips_entries_missing_mmsi():
     assert resp.status_code == 200
     assert resp.json() == {"ok": True, "count": 0}
     mock_set.assert_not_awaited()
+
+
+def _post_adsb(aircraft):
+    with patch.object(telemetry.fstore, "doc_get_cached", AsyncMock(return_value={"org_id": "org-A"})), \
+         patch.object(telemetry.fstore, "doc_set", AsyncMock()) as mock_set:
+        resp = client.post("/telemetry/adsb", json={"aircraft": aircraft})
+    assert resp.status_code == 200
+    return mock_set
+
+
+def test_position_writes_trail_point_with_ttl():
+    _override({"node": True, "node_id": "node-1"})
+    mock_set = _post_adsb([{"icao": "A1B2C3", "lat": 41.1, "lon": -73.8, "altitude_ft": 3000}])
+    trail = _writes_to(mock_set, "aircraft/A1B2C3/positions")
+    assert len(trail) == 1
+    (_, doc_id, point), _ = trail[0]
+    assert doc_id.isdigit()
+    assert (point["lat"], point["lon"], point["altitude_ft"]) == (41.1, -73.8, 3000)
+    assert point["expire_at"] > telemetry.datetime.now(telemetry.timezone.utc)
+
+
+def test_unchanged_position_is_not_rewritten_to_trail():
+    _override({"node": True, "node_id": "node-1"})
+    _post_adsb([{"icao": "A1B2C3", "lat": 41.1, "lon": -73.8}])
+    again = _post_adsb([{"icao": "A1B2C3", "lat": 41.1, "lon": -73.8}])
+    moved = _post_adsb([{"icao": "A1B2C3", "lat": 41.2, "lon": -73.8}])
+    assert _writes_to(again, "aircraft/A1B2C3/positions") == []
+    assert len(_writes_to(moved, "aircraft/A1B2C3/positions")) == 1
+
+
+def test_aircraft_without_position_gets_no_trail_point():
+    _override({"node": True, "node_id": "node-1"})
+    mock_set = _post_adsb([{"icao": "A1B2C3", "callsign": "UAL123"}])
+    assert _writes_to(mock_set, "aircraft/A1B2C3/positions") == []
+    assert len(_writes_to(mock_set, "aircraft")) == 1
diff --git a/drb-frontend/components/MapView.tsx b/drb-frontend/components/MapView.tsx
index 34eee14..10682fd 100644
--- a/drb-frontend/components/MapView.tsx
+++ b/drb-frontend/components/MapView.tsx
@@ -9,13 +9,15 @@ import {
   Polyline,
   Popup,
   TileLayer,
+  Tooltip,
   useMap,
 } from "react-leaflet";
 import L from "leaflet";
-import type { CallRecord, IncidentRecord, NodeRecord, NodeStatus } from "@/lib/types";
+import type { AircraftTrack, CallRecord, IncidentRecord, NodeRecord, NodeStatus } from "@/lib/types";
 import { isKnownSeverity, SEVERITY_COLORS, SEVERITY_LABEL, type Severity } from "@/lib/severity";
 import { MachineOutputNotice } from "@/components/ui/MachineOutputNotice";
 import { useAircraft } from "@/lib/useAircraft";
+import { useAircraftTrail } from "@/lib/useAircraftTrail";
 import { useVessels } from "@/lib/useVessels";
 
 // ── Leaflet icon fix ──────────────────────────────────────────────────────────
@@ -92,36 +94,113 @@ function nodeIcon(status: NodeStatus): L.DivIcon {
   });
 }
 
-// ── Aircraft icon — node-26#9 second-SDR ADS-B overlay ────────────────────────
-function aircraftIcon(trackDeg: number | null): L.DivIcon {
-  const size = 16;
-  const rotation = trackDeg ?? 0;
+// ── Aircraft — node-26#9 second-SDR ADS-B overlay ─────────────────────────────
+// Styled after ADS-B Exchange / tar1090: a sized airliner silhouette with a
+// dark outline, filled by altitude on tar1090's hue ramp, so height reads at a
+// glance and the icon stands out from OSM's own (purple) airport symbols.
+const ALT_HUE_STOPS: [number, number][] = [
+  [0, 20], [2000, 32.5], [4000, 43], [6000, 54], [8000, 72], [9000, 85], [11000, 140], [40000, 300],
+];
+
+function altitudeColor(altFt: number | null): string {
+  if (altFt == null) return "hsl(0, 0%, 55%)";
+  if (altFt <= 0) return "hsl(0, 0%, 45%)"; // on the ground
+  let hue = ALT_HUE_STOPS[ALT_HUE_STOPS.length - 1][1];
+  for (let i = 1; i < ALT_HUE_STOPS.length; i++) {
+    const [a1, h1] = ALT_HUE_STOPS[i];
+    if (altFt <= a1) {
+      const [a0, h0] = ALT_HUE_STOPS[i - 1];
+      hue = h0 + ((h1 - h0) * (altFt - a0)) / (a1 - a0);
+      break;
+    }
+  }
+  return `hsl(${hue.toFixed(0)}, 88%, 48%)`;
+}
+
+const AIRLINER_PATH =
+  "M32 2 C34.2 2 35.2 5 35.2 8 L35.2 23 L61 37.5 L61 42 L35.2 35 L34.2 51 L42.5 57.5 L42.5 61 L32 58.5 " +
+  "L21.5 61 L21.5 57.5 L29.8 51 L28.8 35 L3 42 L3 37.5 L28.8 23 L28.8 8 C28.8 5 29.8 2 32 2 Z";
+
+function aircraftIcon(trackDeg: number | null, altFt: number | null, selected: boolean): L.DivIcon {
+  const size = selected ? 36 : 30;
+  const outline = selected ? "#ffffff" : "#000000";
+  const shadow = selected ? "drop-shadow(0 0 3px #000)" : "drop-shadow(0 1px 1px rgba(0,0,0,.45))";
   return L.divIcon({
     className: "",
-    html: `<div style="width:${size}px;height:${size}px;transform:rotate(${rotation}deg)"><svg width="${size}" height="${size}" viewBox="0 0 24 24" fill="var(--accent)" stroke="var(--surface)" stroke-width="1"><path d="M12 2 L15 11 L22 15 L15 15.5 L14 21 L17 22.5 L12 21.5 L7 22.5 L10 21 L9 15.5 L2 15 L9 11 Z"/></svg></div>`,
+    html:
+      `<div style="width:${size}px;height:${size}px;transform:rotate(${trackDeg ?? 0}deg);filter:${shadow}">` +
+      `<svg width="${size}" height="${size}" viewBox="0 0 64 64"><path d="${AIRLINER_PATH}" ` +
+      `fill="${altitudeColor(altFt)}" stroke="${outline}" stroke-width="${selected ? 3 : 2}" stroke-linejoin="round"/></svg></div>`,
     iconSize: [size, size],
     iconAnchor: [size / 2, size / 2],
   });
 }
 
-function AircraftLayer() {
-  const { aircraft } = useAircraft();
+function AircraftTrail({ icao, current }: { icao: string; current: AircraftTrack }) {
+  const trail = useAircraftTrail(icao);
+  // Extend to the live position so the path always meets the icon.
+  const points = [...trail];
+  if (current.lat != null && current.lon != null) {
+    points.push({ lat: current.lat, lon: current.lon, altitude_ft: current.altitude_ft, t: current.last_seen });
+  }
+  // One segment per leg, colored by altitude like tar1090's track.
   return (
     <>
-      {aircraft
-        .filter((a) => a.lat != null && a.lon != null)
-        .map((a) => (
-          <Marker key={a.icao} position={[a.lat as number, a.lon as number]} icon={aircraftIcon(a.track_deg)}>
-            <Popup minWidth={160}>
-              <div className="space-y-1">
-                <div className="font-semibold">{a.callsign || a.icao}</div>
-                <div className="text-xs text-ink-muted">ICAO {a.icao}</div>
-                {a.altitude_ft != null && <div className="text-xs">Altitude: {Math.round(a.altitude_ft)} ft</div>}
-                {a.ground_speed_kt != null && <div className="text-xs">Speed: {Math.round(a.ground_speed_kt)} kt</div>}
-              </div>
-            </Popup>
-          </Marker>
-        ))}
+      {points.slice(1).map((p, i) => (
+        <Polyline
+          key={`${icao}-${i}`}
+          positions={[[points[i].lat, points[i].lon], [p.lat, p.lon]]}
+          pathOptions={{ color: altitudeColor(p.altitude_ft), weight: 3, opacity: 0.9, lineCap: "round" }}
+          interactive={false}
+        />
+      ))}
+    </>
+  );
+}
+
+function AircraftLayer() {
+  const { aircraft } = useAircraft();
+  const [selected, setSelected] = useState<string | null>(null);
+  const positioned = aircraft.filter((a) => a.lat != null && a.lon != null);
+  const selectedTrack = positioned.find((a) => a.icao === selected);
+
+  return (
+    <>
+      {selectedTrack && <AircraftTrail icao={selectedTrack.icao} current={selectedTrack} />}
+      {positioned.map((a) => (
+        <Marker
+          key={a.icao}
+          position={[a.lat as number, a.lon as number]}
+          icon={aircraftIcon(a.track_deg, a.altitude_ft, a.icao === selected)}
+          zIndexOffset={a.icao === selected ? 1000 : 0}
+          eventHandlers={{
+            click: () => setSelected(a.icao),
+            popupclose: () => setSelected((cur) => (cur === a.icao ? null : cur)),
+          }}
+        >
+          <Tooltip direction="top" offset={[0, -14]}>
+            {a.callsign || a.icao}
+            {a.altitude_ft != null && ` · ${Math.round(a.altitude_ft).toLocaleString()} ft`}
+          </Tooltip>
+          <Popup minWidth={160}>
+            <div className="space-y-1">
+              <div className="font-semibold">{a.callsign || a.icao}</div>
+              <div className="text-xs text-ink-muted">ICAO {a.icao}</div>
+              {a.altitude_ft != null && (
+                <div className="text-xs">
+                  <span
+                    className="inline-block w-2 h-2 rounded-full mr-1 align-middle"
+                    style={{ background: altitudeColor(a.altitude_ft) }}
+                  />
+                  Altitude: {Math.round(a.altitude_ft).toLocaleString()} ft
+                </div>
+              )}
+              {a.ground_speed_kt != null && <div className="text-xs">Speed: {Math.round(a.ground_speed_kt)} kt</div>}
+              {a.track_deg != null && <div className="text-xs">Heading: {Math.round(a.track_deg)}°</div>}
+            </div>
+          </Popup>
+        </Marker>
+      ))}
     </>
   );
 }
diff --git a/drb-frontend/lib/types.ts b/drb-frontend/lib/types.ts
index 98bb5bd..ab1f048 100644
--- a/drb-frontend/lib/types.ts
+++ b/drb-frontend/lib/types.ts
@@ -74,6 +74,14 @@ export interface AircraftTrack {
   last_seen: string;
 }
 
+/** One point of an aircraft's flight path — aircraft/{icao}/positions. */
+export interface AircraftTrailPoint {
+  lat: number;
+  lon: number;
+  altitude_ft: number | null;
+  t: string;
+}
+
 export interface VesselTrack {
   mmsi: string;
   org_id?: string;
diff --git a/drb-frontend/lib/useAircraftTrail.ts b/drb-frontend/lib/useAircraftTrail.ts
new file mode 100644
index 0000000..df42a84
--- /dev/null
+++ b/drb-frontend/lib/useAircraftTrail.ts
@@ -0,0 +1,43 @@
+"use client";
+
+import { useEffect, useState } from "react";
+import { collection, onSnapshot, orderBy, query, where, FirestoreError } from "firebase/firestore";
+import { db } from "@/lib/firebase";
+import type { AircraftTrailPoint } from "@/lib/types";
+
+// Trail points live at aircraft/{icao}/positions (written by c2-core
+// telemetry.py on every position change, TTL-deleted after ~24h). The same
+// icao can fly several legs a day, so only the latest continuous stretch is
+// "this flight": a gap longer than FLIGHT_GAP_MS starts a new one.
+const LOOKBACK_MS = 6 * 60 * 60 * 1000;
+const FLIGHT_GAP_MS = 20 * 60 * 1000;
+
+function currentFlight(points: AircraftTrailPoint[]): AircraftTrailPoint[] {
+  let start = 0;
+  for (let i = 1; i < points.length; i++) {
+    if (new Date(points[i].t).getTime() - new Date(points[i - 1].t).getTime() > FLIGHT_GAP_MS) start = i;
+  }
+  return points.slice(start);
+}
+
+/** Live flight path for one aircraft; pass null to subscribe to nothing. */
+export function useAircraftTrail(icao: string | null) {
+  const [trail, setTrail] = useState<AircraftTrailPoint[]>([]);
+
+  useEffect(() => {
+    setTrail([]);
+    if (!icao) return;
+    // `t` is Python's isoformat() in UTC ("...T17:06:48.755123+00:00"), so it
+    // sorts and range-filters correctly as a string against toISOString()'s
+    // "...T17:06:48.755Z" down to the second — no composite index needed.
+    const since = new Date(Date.now() - LOOKBACK_MS).toISOString();
+    const q = query(collection(db, "aircraft", icao, "positions"), where("t", ">=", since), orderBy("t"));
+    return onSnapshot(
+      q,
+      (snap) => setTrail(currentFlight(snap.docs.map((d) => d.data() as AircraftTrailPoint))),
+      (err: FirestoreError) => console.error("useAircraftTrail:", err),
+    );
+  }, [icao]);
+
+  return trail;
+}
diff --git a/infra/firestore/firestore.indexes.json b/infra/firestore/firestore.indexes.json
index b210727..51647c7 100644
--- a/infra/firestore/firestore.indexes.json
+++ b/infra/firestore/firestore.indexes.json
@@ -77,5 +77,13 @@
       ]
     }
   ],
-  "fieldOverrides": []
+  "fieldOverrides": [
+    {
+      "//": "TTL: flight-trail points (aircraft/{icao}/positions, server-26 telemetry.py) are deleted ~24h after expire_at. indexes: [] because nothing queries on expire_at.",
+      "collectionGroup": "positions",
+      "fieldPath": "expire_at",
+      "ttl": true,
+      "indexes": []
+    }
+  ]
 }
diff --git a/infra/firestore/firestore.rules b/infra/firestore/firestore.rules
index 64bcbb0..3d98748 100644
--- a/infra/firestore/firestore.rules
+++ b/infra/firestore/firestore.rules
@@ -98,6 +98,14 @@ service cloud.firestore {
     match /aircraft/{icao} {
       allow read: if docInMyOrg();
       allow write: if false;
+
+      // Flight trail points. Org is checked against the PARENT aircraft doc
+      // (one get() per query) so the map can query a trail by time alone,
+      // without an org_id filter and the composite index that would need.
+      match /positions/{pointId} {
+        allow read: if inOrg(get(/databases/$(database)/documents/aircraft/$(icao)).data.org_id);
+        allow write: if false;
+      }
     }
 
     match /vessels/{mmsi} {