diff --git a/libraries/AP_InertialSensor/AP_InertialSensor.cpp b/libraries/AP_InertialSensor/AP_InertialSensor.cpp
index 29fd0f288b..504d89b988 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor.cpp
+++ b/libraries/AP_InertialSensor/AP_InertialSensor.cpp
@@ -332,7 +332,8 @@ AP_InertialSensor::AP_InertialSensor() :
     _calibrating(false),
     _log_raw_data(false),
     _backends_detected(false),
-    _dataflash(NULL)
+    _dataflash(NULL),
+    _accel_cal_requires_reboot(false)
 {
     if (_s_instance) {
         AP_HAL::panic("Too many inertial sensors");
@@ -1318,6 +1319,8 @@ void AP_InertialSensor::_acal_save_calibrations()
         hal.console->print("ERR: Trim over maximum of 10 degrees!!");
         _new_trim = false;  //we have either got faulty level during acal or highly misaligned accelerometers 
     }
+
+    _accel_cal_requires_reboot = true;
 }
 
 void AP_InertialSensor::_acal_event_failure()
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor.h b/libraries/AP_InertialSensor/AP_InertialSensor.h
index 433d90dffd..4304b5c201 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor.h
+++ b/libraries/AP_InertialSensor/AP_InertialSensor.h
@@ -241,6 +241,8 @@ public:
 
     // update accel calibrator
     void acal_update();
+
+    bool accel_cal_requires_reboot() const { return _accel_cal_requires_reboot; }
 private:
 
     // load backend drivers
@@ -405,6 +407,8 @@ private:
     float _trim_pitch;
     float _trim_roll;
     bool _new_trim;
+
+    bool _accel_cal_requires_reboot;
 };
 
 #include "AP_InertialSensor_Backend.h"