diff --git a/mission/acs/defs.h b/mission/acs/defs.h
index 3f0b31c4..827047dd 100644
--- a/mission/acs/defs.h
+++ b/mission/acs/defs.h
@@ -71,6 +71,8 @@ static constexpr Event MEKF_INVALID_MODE_VIOLATION = MAKE_EVENT(6, severity::HIG
 //! failed.
 //! P1: Missing information about magnetic field, P2: Missing information about rotational rate
 static constexpr Event SAFE_MODE_CONTROLLER_FAILURE = MAKE_EVENT(7, severity::HIGH);
+//! [EXPORT] : [COMMENT] The TLE for the SPG4 Propagator has become too old.
+static constexpr Event TLE_TOO_OLD = MAKE_EVENT(8, severity::INFO);
 
 extern const char* getModeStr(AcsMode mode);
 
diff --git a/mission/controller/AcsController.cpp b/mission/controller/AcsController.cpp
index 6ae108c5..febe385a 100644
--- a/mission/controller/AcsController.cpp
+++ b/mission/controller/AcsController.cpp
@@ -167,13 +167,19 @@ void AcsController::performSafe() {
   timeval now;
   Clock::getClock_timeval(&now);
 
-  navigation.useSpg4(now, &gpsDataProcessed);
+  ReturnValue_t result = navigation.useSpg4(now, &gpsDataProcessed);
+  if (result == Sgp4Propagator::TLE_TOO_OLD and not tleTooOldFlag) {
+    triggerEvent(acs::TLE_TOO_OLD);
+    tleTooOldFlag = true;
+  } else if (result != Sgp4Propagator::TLE_TOO_OLD) {
+    tleTooOldFlag = false;
+  }
   sensorProcessing.process(now, &sensorValues, &mgmDataProcessed, &susDataProcessed,
                            &gyrDataProcessed, &gpsDataProcessed, &acsParameters);
   fusedRotationEstimation.estimateFusedRotationRateSafe(&susDataProcessed, &mgmDataProcessed,
                                                         &gyrDataProcessed, &fusedRotRateData);
-  ReturnValue_t result = navigation.useMekf(&sensorValues, &gyrDataProcessed, &mgmDataProcessed,
-                                            &susDataProcessed, &mekfData, &acsParameters);
+  result = navigation.useMekf(&sensorValues, &gyrDataProcessed, &mgmDataProcessed,
+                              &susDataProcessed, &mekfData, &acsParameters);
   if (result != MultiplicativeKalmanFilter::MEKF_RUNNING &&
       result != MultiplicativeKalmanFilter::MEKF_INITIALIZED) {
     if (not mekfInvalidFlag) {
@@ -293,13 +299,19 @@ void AcsController::performDetumble() {
   timeval now;
   Clock::getClock_timeval(&now);
 
-  navigation.useSpg4(now, &gpsDataProcessed);
+  ReturnValue_t result = navigation.useSpg4(now, &gpsDataProcessed);
+  if (result == Sgp4Propagator::TLE_TOO_OLD and not tleTooOldFlag) {
+    triggerEvent(acs::TLE_TOO_OLD);
+    tleTooOldFlag = true;
+  } else {
+    tleTooOldFlag = false;
+  }
   sensorProcessing.process(now, &sensorValues, &mgmDataProcessed, &susDataProcessed,
                            &gyrDataProcessed, &gpsDataProcessed, &acsParameters);
   fusedRotationEstimation.estimateFusedRotationRateSafe(&susDataProcessed, &mgmDataProcessed,
                                                         &gyrDataProcessed, &fusedRotRateData);
-  ReturnValue_t result = navigation.useMekf(&sensorValues, &gyrDataProcessed, &mgmDataProcessed,
-                                            &susDataProcessed, &mekfData, &acsParameters);
+  result = navigation.useMekf(&sensorValues, &gyrDataProcessed, &mgmDataProcessed,
+                              &susDataProcessed, &mekfData, &acsParameters);
   if (result != MultiplicativeKalmanFilter::MEKF_RUNNING &&
       result != MultiplicativeKalmanFilter::MEKF_INITIALIZED) {
     if (not mekfInvalidFlag) {
@@ -380,11 +392,17 @@ void AcsController::performPointingCtrl() {
   timeval now;
   Clock::getClock_timeval(&now);
 
-  navigation.useSpg4(now, &gpsDataProcessed);
+  ReturnValue_t result = navigation.useSpg4(now, &gpsDataProcessed);
+  if (result == Sgp4Propagator::TLE_TOO_OLD and not tleTooOldFlag) {
+    triggerEvent(acs::TLE_TOO_OLD);
+    tleTooOldFlag = true;
+  } else {
+    tleTooOldFlag = false;
+  }
   sensorProcessing.process(now, &sensorValues, &mgmDataProcessed, &susDataProcessed,
                            &gyrDataProcessed, &gpsDataProcessed, &acsParameters);
-  ReturnValue_t result = navigation.useMekf(&sensorValues, &gyrDataProcessed, &mgmDataProcessed,
-                                            &susDataProcessed, &mekfData, &acsParameters);
+  result = navigation.useMekf(&sensorValues, &gyrDataProcessed, &mgmDataProcessed,
+                              &susDataProcessed, &mekfData, &acsParameters);
   if (result != MultiplicativeKalmanFilter::MEKF_RUNNING &&
       result != MultiplicativeKalmanFilter::MEKF_INITIALIZED) {
     mekfInvalidCounter++;
diff --git a/mission/controller/AcsController.h b/mission/controller/AcsController.h
index a40dba3b..e03f2a55 100644
--- a/mission/controller/AcsController.h
+++ b/mission/controller/AcsController.h
@@ -3,6 +3,7 @@
 
 #include <eive/objects.h>
 #include <fsfw/controller/ExtendedControllerBase.h>
+#include <fsfw/coordinates/Sgp4Propagator.h>
 #include <fsfw/globalfunctions/math/VectorOperations.h>
 #include <fsfw/health/HealthTable.h>
 #include <fsfw/parameters/ParameterHelper.h>
@@ -61,6 +62,7 @@ class AcsController : public ExtendedControllerBase, public ReceivesParameterMes
 
   ParameterHelper parameterHelper;
 
+  bool tleTooOldFlag = false;
   uint8_t detumbleCounter = 0;
   uint8_t multipleRwUnavailableCounter = 0;
   bool mekfInvalidFlag = false;
diff --git a/mission/controller/acs/Navigation.cpp b/mission/controller/acs/Navigation.cpp
index 61f9bda4..4726586b 100644
--- a/mission/controller/acs/Navigation.cpp
+++ b/mission/controller/acs/Navigation.cpp
@@ -45,7 +45,7 @@ void Navigation::resetMekf(acsctrl::MekfData *mekfData) {
   mekfStatus = multiplicativeKalmanFilter.reset(mekfData);
 }
 
-void Navigation::useSpg4(timeval now, acsctrl::GpsDataProcessed *gpsDataProcessed) {
+ReturnValue_t Navigation::useSpg4(timeval now, acsctrl::GpsDataProcessed *gpsDataProcessed) {
   double position[3] = {0, 0, 0};
   double velocity[3] = {0, 0, 0};
   ReturnValue_t result = sgp4Propagator.propagate(position, velocity, now, 0);
@@ -75,6 +75,7 @@ void Navigation::useSpg4(timeval now, acsctrl::GpsDataProcessed *gpsDataProcesse
       }
     }
   }
+  return result;
 }
 
 ReturnValue_t Navigation::updateTle(const uint8_t *line1, const uint8_t *line2) {
diff --git a/mission/controller/acs/Navigation.h b/mission/controller/acs/Navigation.h
index bc39555f..2785ff2e 100644
--- a/mission/controller/acs/Navigation.h
+++ b/mission/controller/acs/Navigation.h
@@ -21,7 +21,7 @@ class Navigation {
                         AcsParameters *acsParameters);
   void resetMekf(acsctrl::MekfData *mekfData);
 
-  void useSpg4(timeval now, acsctrl::GpsDataProcessed *gpsDataProcessed);
+  ReturnValue_t useSpg4(timeval now, acsctrl::GpsDataProcessed *gpsDataProcessed);
   ReturnValue_t updateTle(const uint8_t *line1, const uint8_t *line2);
 
  protected: