diff --git a/html/index.html b/html/index.html
index a24c048..da09654 100644
--- a/html/index.html
+++ b/html/index.html
@@ -910,7 +910,7 @@
                           <span> <input id="altimeter_input" type="number" step="0.01" value="29.92" class="searchInput"></span>
                           <span> <button class="formButton" type="submit">Set</button></span>
                           <span> <button class="formButton" type="button" id="altimeter_set_standard">Standard</button>
-                          <span> <button class="formButton" type="button" id="altimeter_set_selected">From Plane</button>
+                          <span> <button class="formButton" type="button" disabled id="altimeter_set_selected">From Plane</button>
                         </form>
                       </td>
                     </tr>
diff --git a/html/script.js b/html/script.js
index 228839d..96b5f50 100644
--- a/html/script.js
+++ b/html/script.js
@@ -3368,6 +3368,12 @@ let somethingSelected = false;
 function refreshSelected() {
     const selected = SelectedPlane;
 
+    if (!selected || !selected.nav_qnh) {
+        jQuery('#altimeter_set_selected').prop("disabled", true);
+    } else {
+        jQuery('#altimeter_set_selected').prop("disabled", false);
+    }
+
     if (!selected) {
         if (somethingSelected) {
             adjustInfoBlock();
diff --git a/html/style.css b/html/style.css
index ffd4844..475ffc9 100644
--- a/html/style.css
+++ b/html/style.css
@@ -350,10 +350,13 @@ select {
 
 .formButton {
     font-size: var(--FS2);
-    color:var(--TXTCOLOR3);
+    color:var(--TXTCOLOR2);
     background-color: var(--BGCOLOR2);
     border-color: var(--BGCOLOR1);
 }
+.formButton:disabled {
+    color:var(--TXTCOLOR3);
+}
 
 select.error, textarea.error, input.error {
     color: #FF0000;