diff --git a/ArduCopter/crash_check.cpp b/ArduCopter/crash_check.cpp
index 1df3b1dd93..3b17cd0007 100644
--- a/ArduCopter/crash_check.cpp
+++ b/ArduCopter/crash_check.cpp
@@ -4,7 +4,7 @@
 
 // Code to detect a crash main ArduCopter code
 #define CRASH_CHECK_TRIGGER_SEC         2       // 2 seconds inverted indicates a crash
-#define CRASH_CHECK_ANGLE_DEVIATION_CD  3000.0f // 30 degrees beyond angle max is signal we are inverted
+#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
 
 // crash_check - disarms motors if a crash has been detected
@@ -33,8 +33,8 @@ void Copter::crash_check()
     }
 
     // check for angle error over 30 degrees
-    const Vector3f angle_error = attitude_control.get_att_error_rot_vec_cd();
-    if (norm(angle_error.x, angle_error.y) <= CRASH_CHECK_ANGLE_DEVIATION_CD) {
+    const float angle_error = attitude_control.get_att_error_angle_deg();
+    if (angle_error <= CRASH_CHECK_ANGLE_DEVIATION_DEG) {
         crash_counter = 0;
         return;
     }
@@ -99,8 +99,8 @@ void Copter::parachute_check()
     }
 
     // check for angle error over 30 degrees
-    const Vector3f angle_error = attitude_control.get_att_error_rot_vec_cd();
-    if (norm(angle_error.x, angle_error.y) <= CRASH_CHECK_ANGLE_DEVIATION_CD) {
+    const float angle_error = attitude_control.get_att_error_angle_deg();
+    if (angle_error <= CRASH_CHECK_ANGLE_DEVIATION_DEG) {
         control_loss_count = 0;
         return;
     }
diff --git a/ArduCopter/land_detector.cpp b/ArduCopter/land_detector.cpp
index 114d6863f1..739add6d11 100644
--- a/ArduCopter/land_detector.cpp
+++ b/ArduCopter/land_detector.cpp
@@ -2,6 +2,11 @@
 
 #include "Copter.h"
 
+// Code to detect a crash main ArduCopter code
+#define LAND_CHECK_ANGLE_ERROR_DEG  30.0f       // maximum angle error to be considered landing
+#define LAND_CHECK_LARGE_ANGLE_CD   1500.0f     // maximum angle target to be considered landing
+#define LAND_CHECK_ACCEL_MOVING     3.0f        // maximum acceleration after subtracting gravity
+
 
 // counter to verify landings
 static uint32_t land_detector_count = 0;
@@ -141,16 +146,16 @@ void Copter::update_throttle_thr_mix()
 
         // check for aggressive flight requests - requested roll or pitch angle below 15 degrees
         const Vector3f angle_target = attitude_control.get_att_target_euler_cd();
-        bool large_angle_request = (norm(angle_target.x, angle_target.y) > 1500.0f);
+        bool large_angle_request = (norm(angle_target.x, angle_target.y) > LAND_CHECK_LARGE_ANGLE_CD);
 
         // check for large external disturbance - angle error over 30 degrees
-        const Vector3f angle_error = attitude_control.get_att_error_rot_vec_cd();
-        bool large_angle_error = (norm(angle_error.x, angle_error.y) > 3000.0f);
+        const float angle_error = attitude_control.get_att_error_angle_deg();
+        bool large_angle_error = (angle_error > LAND_CHECK_ANGLE_ERROR_DEG);
 
         // check for large acceleration - falling or high turbulence
         Vector3f accel_ef = ahrs.get_accel_ef_blended();
         accel_ef.z += GRAVITY_MSS;
-        bool accel_moving = (accel_ef.length() > 3.0f);
+        bool accel_moving = (accel_ef.length() > LAND_CHECK_ACCEL_MOVING);
 
         // check for requested decent
         bool descent_not_demanded = pos_control.get_desired_velocity().z >= 0.0f;