diff --git a/libraries/AP_Airspeed/AP_Airspeed.cpp b/libraries/AP_Airspeed/AP_Airspeed.cpp
index 7ad908378c..340bef649b 100644
--- a/libraries/AP_Airspeed/AP_Airspeed.cpp
+++ b/libraries/AP_Airspeed/AP_Airspeed.cpp
@@ -755,6 +755,40 @@ bool AP_Airspeed::healthy(uint8_t i) const {
     return ok;
 }
 
+// return the current airspeed in m/s
+float AP_Airspeed::get_airspeed(uint8_t i) const {
+    if (!enabled(i)) {
+        // we can't have negative airspeed so sending an obviously invalid value
+        return -1.0;
+    }
+    return state[i].airspeed;
+}
+
+// return the unfiltered airspeed in m/s
+float AP_Airspeed::get_raw_airspeed(uint8_t i) const {
+    if (!enabled(i)) {
+        // we can't have negative airspeed so sending an obviously invalid value
+        return -1.0;
+    }
+    return state[i].raw_airspeed;
+}
+
+// return the differential pressure in Pascal for the last airspeed reading
+float AP_Airspeed::get_differential_pressure(uint8_t i) const {
+    if (!enabled(i)) {
+        return 0.0;
+    }
+    return state[i].last_pressure;
+}
+
+// return the current corrected pressure
+float AP_Airspeed::get_corrected_pressure(uint8_t i) const {
+    if (!enabled(i)) {
+        return 0.0;
+    }
+    return state[i].corrected_pressure;
+}
+
 #else  // build type is not appropriate; provide a dummy implementation:
 const AP_Param::GroupInfo AP_Airspeed::var_info[] = { AP_GROUPEND };
 
@@ -764,6 +798,8 @@ void AP_Airspeed::calibrate(bool in_startup) {}
 bool AP_Airspeed::use(uint8_t i) const { return false; }
 bool AP_Airspeed::enabled(uint8_t i) const { return false; }
 bool AP_Airspeed::healthy(uint8_t i) const { return false; }
+float AP_Airspeed::get_airspeed(uint8_t i) const { return 0.0; }
+float AP_Airspeed::get_differential_pressure(uint8_t i) const { return 0.0; }
 
 #if HAL_MSP_AIRSPEED_ENABLED
 void AP_Airspeed::handle_msp(const MSP::msp_airspeed_data_message_t &pkt) {}
diff --git a/libraries/AP_Airspeed/AP_Airspeed.h b/libraries/AP_Airspeed/AP_Airspeed.h
index 7e9bd74a95..2d0336be31 100644
--- a/libraries/AP_Airspeed/AP_Airspeed.h
+++ b/libraries/AP_Airspeed/AP_Airspeed.h
@@ -73,15 +73,11 @@ public:
     void calibrate(bool in_startup);
 
     // return the current airspeed in m/s
-    float get_airspeed(uint8_t i) const {
-        return state[i].airspeed;
-    }
+    float get_airspeed(uint8_t i) const;
     float get_airspeed(void) const { return get_airspeed(primary); }
 
     // return the unfiltered airspeed in m/s
-    float get_raw_airspeed(uint8_t i) const {
-        return state[i].raw_airspeed;
-    }
+    float get_raw_airspeed(uint8_t i) const;
     float get_raw_airspeed(void) const { return get_raw_airspeed(primary); }
 
     // return the current airspeed ratio (dimensionless)
@@ -114,9 +110,7 @@ public:
     bool enabled(void) const { return enabled(primary); }
 
     // return the differential pressure in Pascal for the last airspeed reading
-    float get_differential_pressure(uint8_t i) const {
-        return state[i].last_pressure;
-    }
+    float get_differential_pressure(uint8_t i) const;
     float get_differential_pressure(void) const { return get_differential_pressure(primary); }
 
     // update airspeed ratio calibration
@@ -173,9 +167,7 @@ public:
     static AP_Airspeed *get_singleton() { return _singleton; }
 
     // return the current corrected pressure, public for AP_Periph
-    float get_corrected_pressure(uint8_t i) const {
-        return state[i].corrected_pressure;
-    }
+    float get_corrected_pressure(uint8_t i) const;
     float get_corrected_pressure(void) const {
         return get_corrected_pressure(primary);
     }