diff --git a/conf/messages.xml b/conf/messages.xml
index 1c8e01b03d1..76420029183 100644
--- a/conf/messages.xml
+++ b/conf/messages.xml
@@ -1938,8 +1938,8 @@
   </message>
 
   <message name="AMSL" id="222">
-    <field name="AMSL_BARO" type="float" unit="ft"/>
-    <field name="AMSL_GPS" type="float" unit="ft"/>
+    <field name="AMSL_BARO" type="float" unit="ft" alt_unit="m"/>
+    <field name="AMSL_GPS" type="float" unit="ft" alt_unit="m"/>
   </message>
 
  <!--223 is free -->
diff --git a/conf/units.xml b/conf/units.xml
index acfd74dff6a..e8f485c98c6 100644
--- a/conf/units.xml
+++ b/conf/units.xml
@@ -1,6 +1,8 @@
 <!-- Table of default units convertion -->
 <!-- used to convert from unit to alt_unit (messages) or code_unit (airframe) -->
 <units>
+  <unit from="m" to="ft" coef="0.3048"/>
+  <unit from="ft to="m" coef="3.28084"/>
   <unit from="m" to="cm" coef="100."/>
   <unit from="cm" to="m" coef="0.01"/>
   <unit from="m/s" to="cm/s" coef="100."/>