diff --git a/app/autonomy/LocalizationMeasurements.js b/app/autonomy/LocalizationMeasurements.js
index d5156419..d6c29fd2 100644
--- a/app/autonomy/LocalizationMeasurements.js
+++ b/app/autonomy/LocalizationMeasurements.js
@@ -296,8 +296,17 @@ export function buildGnssMeasurement(snapshot, sensorConfig, rng, state = {}) {
     }
 
     const outageProbability = Number(faults.outageProbability ?? 0);
-    const inOutage = state.inOutage || (outageProbability > 0 && rng.next() < outageProbability);
-    if (inOutage) {
+    // A missing or zero duration means the outage lasts to the end of the run.
+    const outageDurationNs = Math.max(0, Number(faults.outageDurationSec || 0)) * 1e9;
+    const outageEnded = state.inOutage
+        && state.outageEndNs != null
+        && snapshot.captureTimeNs >= state.outageEndNs;
+    const continuing = state.inOutage && !outageEnded;
+    const starting = !continuing && outageProbability > 0 && rng.next() < outageProbability;
+    if (continuing || starting) {
+        const outageEndNs = starting
+            ? (outageDurationNs > 0 ? snapshot.captureTimeNs + outageDurationNs : null)
+            : state.outageEndNs ?? null;
         return {
             measurement: {
                 status: -1,
@@ -309,7 +318,7 @@ export function buildGnssMeasurement(snapshot, sensorConfig, rng, state = {}) {
                 positionCovarianceType: 0,
                 noFix: true,
             },
-            nextState: { ...state, multipath: nextMultipath, inOutage: true, lastCaptureTimeNs: snapshot.captureTimeNs },
+            nextState: { ...state, multipath: nextMultipath, inOutage: true, outageEndNs, lastCaptureTimeNs: snapshot.captureTimeNs },
         };
     }
 
@@ -338,7 +347,7 @@ export function buildGnssMeasurement(snapshot, sensorConfig, rng, state = {}) {
             positionCovarianceType: 2,
             noFix: false,
         },
-        nextState: { ...state, multipath: nextMultipath, inOutage: false, lastCaptureTimeNs: snapshot.captureTimeNs, dropped: false },
+        nextState: { ...state, multipath: nextMultipath, inOutage: false, outageEndNs: null, lastCaptureTimeNs: snapshot.captureTimeNs, dropped: false },
     };
 }
 
diff --git a/app/simulation/sensors/SensorTypeRegistry.js b/app/simulation/sensors/SensorTypeRegistry.js
index 9df88d2d..10162f06 100644
--- a/app/simulation/sensors/SensorTypeRegistry.js
+++ b/app/simulation/sensors/SensorTypeRegistry.js
@@ -174,6 +174,7 @@ const gnssRunFields = [
     { label: "Position noise N (m)", path: ["calibration", "positionNoiseEnu", "y"], control: "number", min: 0, step: 0.001, advanced: true },
     { label: "Dropout probability", path: ["calibration", "faults", "dropoutProbability"], control: "number", min: 0, max: 1, step: 0.001, advanced: true },
     { label: "Outage probability", path: ["calibration", "faults", "outageProbability"], control: "number", min: 0, max: 1, step: 0.001, advanced: true },
+    { label: "Outage duration (s, 0 = rest of run)", path: ["calibration", "faults", "outageDurationSec"], control: "number", min: 0, step: 0.1, advanced: true },
 ];
 
 const wheelOdometryRunFields = [
diff --git a/docs/run-manifests.md b/docs/run-manifests.md
index d134a41c..664a97cb 100644
--- a/docs/run-manifests.md
+++ b/docs/run-manifests.md
@@ -342,7 +342,7 @@ appearance/analytic readback.
 | Sensor | Rate | Key calibration | Units |
 | --- | --- | --- | --- |
 | IMU | 100 Hz | `gravity`, per-axis `angularVelocityStdDev`, `linearAccelerationStdDev`, drift τ, saturation | rad/s, m/s² |
-| GNSS | 10 Hz | `datum` (lat/lng/alt), `positionNoiseEnu`, `faults.dropoutProbability`, `faults.outageProbability`, multipath τ | deg, m |
+| GNSS | 10 Hz | `datum` (lat/lng/alt), `positionNoiseEnu`, `faults.dropoutProbability`, `faults.outageProbability`, `faults.outageDurationSec` (0 or absent: outage lasts to the end of the run), multipath τ | deg, m |
 | Wheel odometry | 50 Hz | `wheelRadius`, `ticksPerRevolution`, `trackWidth`, `slipFactor`, pose/twist noise | m, ticks/rev |
 
 GNSS treats map/odom position as ENU offset from the manifest datum. Wheel odometry integrates an independent measured `odom → base_link` estimate; oracle truth on `/oracle/vehicle/odometry` remains isolated for scoring.
diff --git a/tests/localization-sensors.test.js b/tests/localization-sensors.test.js
index fe0a249b..d444c41b 100644
--- a/tests/localization-sensors.test.js
+++ b/tests/localization-sensors.test.js
@@ -113,6 +113,30 @@ test("WGS84 conversion returns datum at zero ENU offset", () => {
     assert.ok(Math.abs(converted.lng - datum.lng) < 1e-4);
 });
 
+test("GNSS outage ends after outageDurationSec and is permanent without it", () => {
+    const run = (faults) => {
+        const start = normalizeRunSensor({ type: "gnss", calibration: { faults: { ...faults, outageProbability: 1 } } });
+        const after = normalizeRunSensor({ type: "gnss", calibration: { faults: { ...faults, outageProbability: 0 } } });
+        const rng = new SeededRNG("gnss-outage-duration");
+        let state = createMeasurementSeedState(start, rng);
+        const noFix = [];
+        // 10 Hz fixes. The outage starts on the first fix only.
+        for (let index = 1; index <= 20; index += 1) {
+            const snapshot = captureVehicleSnapshot(mockVehicle(), index * 100_000_000);
+            const result = buildGnssMeasurement(snapshot, index === 1 ? start : after, rng, state);
+            state = { ...state, ...result.nextState };
+            noFix.push(result.measurement.noFix);
+        }
+        return noFix;
+    };
+    // Starts at 0.1 s and ends at 0.6 s: fixes at 0.1 through 0.5 s have no fix.
+    const timed = run({ outageDurationSec: 0.5 });
+    assert.deepEqual(timed.slice(0, 5), [true, true, true, true, true]);
+    assert.ok(timed.slice(5).every((value) => value === false));
+    assert.ok(run({}).every((value) => value === true));
+    assert.ok(run({ outageDurationSec: 0 }).every((value) => value === true));
+});
+
 test("GNSS dropout returns no sample and outage emits no-fix status", () => {
     const config = normalizeRunSensor({
         type: "gnss",