diff --git a/src/modules/sih/sih.cpp b/src/modules/sih/sih.cpp
index 76e0bde5d6..16f6029e6f 100644
--- a/src/modules/sih/sih.cpp
+++ b/src/modules/sih/sih.cpp
@@ -348,8 +348,6 @@ void Sih::generate_force_and_torques()
 // apply the equations of motion of a rigid body and integrate one step
 void Sih::equations_of_motion()
 {
-    static bool grounded=true;  // the simulation starts with the vehicle on the ground
-
     _C_IB=_q.to_dcm();  // body to inertial transformation
 
     // Equations of motion of a rigid body
@@ -359,26 +357,24 @@ void Sih::equations_of_motion()
     _w_B_dot=_Im1*(_Mt_B+_Ma_B-_w_B.cross(_I*_w_B));    // conservation of angular momentum
 
     // fake ground, avoid free fall
-    if(_p_I(2)>0.0f && (_v_I_dot(2)>0.0f || _v_I(2)>0.0f))
-    {
-        if (grounded==false)    // if we just hit the floor
+    if(_p_I(2)>0.0f && (_v_I_dot(2)>0.0f || _v_I(2)>0.0f)) {
+        if (!_grounded) {    // if we just hit the floor
             // for the accelerometer, compute the acceleration that will stop the vehicle in one time step
             _v_I_dot=-_v_I/_dt;
-        else
+        } else {
             _v_I_dot.setZero();
+        }
         _v_I.setZero();
         _w_B.setZero();
-        grounded=true;
-    }
-    else
-    {
+        _grounded = true;
+    } else {
         // integration: Euler forward
         _p_I = _p_I + _p_I_dot*_dt;
         _v_I = _v_I + _v_I_dot*_dt;
         _q = _q+_q_dot*_dt;     // as given in attitude_estimator_q_main.cpp
         _q.normalize();
         _w_B = _w_B + _w_B_dot*_dt;
-        grounded=false;
+        _grounded = false;
     }
 }
 
diff --git a/src/modules/sih/sih.hpp b/src/modules/sih/sih.hpp
index 6132e88f9e..0dde73782c 100644
--- a/src/modules/sih/sih.hpp
+++ b/src/modules/sih/sih.hpp
@@ -146,13 +146,13 @@ private:
 
 	px4_sem_t       _data_semaphore;
 
-	int32_t     _counter = 0;
 	hrt_call    _timer_call;
 	hrt_abstime _last_run;
 	hrt_abstime _gps_time;
 	hrt_abstime _serial_time;
 	hrt_abstime _now;
 	float       _dt;            // sampling time [s]
+	bool        _grounded{true};// whether the vehicle is on the ground
 
 	matrix::Vector3f    _T_B;           // thrust force in body frame [N]
 	matrix::Vector3f    _Fa_I;          // aerodynamic force in inertial frame [N]