diff --git a/ArduSub/crash_check.cpp b/ArduSub/crash_check.cpp
deleted file mode 100644
index 37fef2055a..0000000000
--- a/ArduSub/crash_check.cpp
+++ /dev/null
@@ -1,61 +0,0 @@
-#include "Sub.h"
-
-// Code to detect a crash
-#define CRASH_CHECK_TRIGGER_SEC         2       // 2 seconds inverted indicates a crash
-#define CRASH_CHECK_ANGLE_DEVIATION_DEG 30.0f   // 30 degrees beyond angle max is signal we are inverted
-#define CRASH_CHECK_ACCEL_MAX           3.0f    // vehicle must be accelerating less than 3m/s/s to be considered crashed
-#define CRASH_CHECK_ACCEL_LPF_CUTOFF    1.0f    // LPF cutoff frequency for acceleration vector
-
-// crash_check - disarms motors if a crash has been detected
-// crashes are detected by the vehicle being more than 20 degrees beyond it's angle limits continuously for more than 1 second
-// called at MAIN_LOOP_RATE
-void Sub::crash_check(uint32_t dt_seconds)
-{
-    static uint16_t crash_counter;  // number of iterations vehicle may have been crashed
-
-    static LowPassFilterVector3f crash_accel_ef_filter(CRASH_CHECK_ACCEL_LPF_CUTOFF); // acceleration for checking if crashed
-
-    // update 1hz filtered acceleration
-    Vector3f accel_ef = ahrs.get_accel_ef_blended();
-    accel_ef.z += GRAVITY_MSS;
-
-    crash_accel_ef_filter.apply(accel_ef, dt_seconds);
-
-    // return immediately if disarmed, or crash checking disabled
-    if (!motors.armed() || g.fs_crash_check == 0) {
-        crash_counter = 0;
-        return;
-    }
-
-    // return immediately if we are not in an angle stabilized flight mode
-    if (control_mode == ACRO || control_mode == MANUAL) {
-        crash_counter = 0;
-        return;
-    }
-
-    // vehicle not crashed if 1hz filtered acceleration is more than 3m/s (1G on Z-axis has been subtracted)
-    if (crash_accel_ef_filter.get().length() >= CRASH_CHECK_ACCEL_MAX) {
-        crash_counter = 0;
-        return;
-    }
-
-    // check for angle error over 30 degrees
-    const float angle_error = attitude_control.get_att_error_angle_deg();
-    if (angle_error <= CRASH_CHECK_ANGLE_DEVIATION_DEG) {
-        crash_counter = 0;
-        return;
-    }
-
-    // we may be crashing
-    crash_counter++;
-
-    // check if crashing for 2 seconds
-    if (crash_counter >= (CRASH_CHECK_TRIGGER_SEC * scheduler.get_loop_rate_hz())) {
-        // log an error in the dataflash
-        Log_Write_Error(ERROR_SUBSYSTEM_CRASH_CHECK, ERROR_CODE_CRASH_CHECK_CRASH);
-        // send message to gcs
-        gcs_send_text(MAV_SEVERITY_EMERGENCY,"Crash: Disarming");
-        // disarm motors
-        init_disarm_motors();
-    }
-}
diff --git a/ArduSub/failsafe.cpp b/ArduSub/failsafe.cpp
index c27591972a..b60ec4e4b5 100644
--- a/ArduSub/failsafe.cpp
+++ b/ArduSub/failsafe.cpp
@@ -287,6 +287,66 @@ void Sub::failsafe_gcs_check()
     }
 }
 
+// Code to detect a crash
+#define CRASH_CHECK_TRIGGER_SEC         2       // 2 seconds inverted indicates a crash
+#define CRASH_CHECK_ANGLE_DEVIATION_DEG 30.0f   // 30 degrees beyond angle max is signal we are inverted
+#define CRASH_CHECK_ACCEL_MAX           3.0f    // vehicle must be accelerating less than 3m/s/s to be considered crashed
+#define CRASH_CHECK_ACCEL_LPF_CUTOFF    1.0f    // LPF cutoff frequency for acceleration vector
+
+// crash_check - disarms motors if a crash has been detected
+// crashes are detected by the vehicle being more than 20 degrees beyond it's angle limits continuously for more than 1 second
+// called at MAIN_LOOP_RATE
+void Sub::crash_check(uint32_t dt_seconds)
+{
+    static uint16_t crash_counter;  // number of iterations vehicle may have been crashed
+
+    static LowPassFilterVector3f crash_accel_ef_filter(CRASH_CHECK_ACCEL_LPF_CUTOFF); // acceleration for checking if crashed
+
+    // update 1hz filtered acceleration
+    Vector3f accel_ef = ahrs.get_accel_ef_blended();
+    accel_ef.z += GRAVITY_MSS;
+
+    crash_accel_ef_filter.apply(accel_ef, dt_seconds);
+
+    // return immediately if disarmed, or crash checking disabled
+    if (!motors.armed() || g.fs_crash_check == 0) {
+        crash_counter = 0;
+        return;
+    }
+
+    // return immediately if we are not in an angle stabilized flight mode
+    if (control_mode == ACRO || control_mode == MANUAL) {
+        crash_counter = 0;
+        return;
+    }
+
+    // vehicle not crashed if 1hz filtered acceleration is more than 3m/s (1G on Z-axis has been subtracted)
+    if (crash_accel_ef_filter.get().length() >= CRASH_CHECK_ACCEL_MAX) {
+        crash_counter = 0;
+        return;
+    }
+
+    // check for angle error over 30 degrees
+    const float angle_error = attitude_control.get_att_error_angle_deg();
+    if (angle_error <= CRASH_CHECK_ANGLE_DEVIATION_DEG) {
+        crash_counter = 0;
+        return;
+    }
+
+    // we may be crashing
+    crash_counter++;
+
+    // check if crashing for 2 seconds
+    if (crash_counter >= (CRASH_CHECK_TRIGGER_SEC * scheduler.get_loop_rate_hz())) {
+        // log an error in the dataflash
+        Log_Write_Error(ERROR_SUBSYSTEM_CRASH_CHECK, ERROR_CODE_CRASH_CHECK_CRASH);
+        // send message to gcs
+        gcs_send_text(MAV_SEVERITY_EMERGENCY,"Crash: Disarming");
+        // disarm motors
+        init_disarm_motors();
+    }
+}
+
 // executes terrain failsafe if data is missing for longer than a few seconds
 //  missing_data should be set to true if the vehicle failed to navigate because of missing data, false if navigation is proceeding successfully
 void Sub::failsafe_terrain_check()
@@ -386,4 +446,3 @@ bool Sub::should_disarm_on_failsafe()
         break;
     }
 }
-