From b327f80946aaef786a75cf51588dad85f802d728 Mon Sep 17 00:00:00 2001
From: Hwurzburg <hwurzburg@yahoo.com>
Date: Tue, 5 Oct 2021 17:42:22 -0500
Subject: [PATCH] AP_Airspeed: do not cal if backend does not exist

---
 libraries/AP_Airspeed/AP_Airspeed.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libraries/AP_Airspeed/AP_Airspeed.cpp b/libraries/AP_Airspeed/AP_Airspeed.cpp
index 195c656ab6..3ef378eb98 100644
--- a/libraries/AP_Airspeed/AP_Airspeed.cpp
+++ b/libraries/AP_Airspeed/AP_Airspeed.cpp
@@ -486,6 +486,10 @@ void AP_Airspeed::calibrate(bool in_startup)
         if (in_startup && param[i].skip_cal) {
             continue;
         }
+        if (sensor[i] == nullptr) {
+            GCS_SEND_TEXT(MAV_SEVERITY_INFO,"Airspeed %u not initalized, cannot cal", i+1);
+            continue;
+        }
         state[i].cal.start_ms = AP_HAL::millis();
         state[i].cal.count = 0;
         state[i].cal.sum = 0;