diff --git a/sw/ground_segment/cockpit/map2d.ml b/sw/ground_segment/cockpit/map2d.ml
index bd19830bdf..be456996ed 100644
--- a/sw/ground_segment/cockpit/map2d.ml
+++ b/sw/ground_segment/cockpit/map2d.ml
@@ -1347,7 +1347,7 @@ let _main =
   and center = ref ""
   and zoom = ref 1.
   and maximize = ref false
-  and projection= ref G.UTM
+  and projection = ref G.Mercator
   and auto_ortho = ref false
   and mplayer = ref ""
   and plugin_window = ref "" in
@@ -1360,7 +1360,8 @@ let _main =
       "-center_ac", Arg.Set auto_center_new_ac, "Centers the map on any new A/C";
       "-plugin", Arg.Set_string  plugin_window, "External X application (launched the id of the plugin window as argument)";
       "-mplayer", Arg.Set_string mplayer, "Launch mplayer with the given argument as X plugin";
-      "-mercator", Arg.Unit (fun () -> projection:=G.Mercator),"Switch to (Google Maps) Mercator projection";
+      "-utm", Arg.Unit (fun () -> projection:=G.Mercator),"Switch to UTM local projection";
+      "-mercator", Arg.Unit (fun () -> projection:=G.Mercator),"Switch to (Google Maps) Mercator projection, default";
       "-lambertIIe", Arg.Unit (fun () -> projection:=G.LambertIIe),"Switch to LambertIIe projection";
       "-ign", Arg.String (fun s -> ign:=true; IGN.data_path := s), "IGN tiles path";
       "-ortho", Arg.Set_string get_bdortho, "IGN tiles path";
diff --git a/sw/lib/ocaml/mapFP.ml b/sw/lib/ocaml/mapFP.ml
index a3c8c554b9..5e803218d1 100644
--- a/sw/lib/ocaml/mapFP.ml
+++ b/sw/lib/ocaml/mapFP.ml
@@ -85,9 +85,13 @@ let update_xml = fun xml_tree utm0 wp ->
   let xml_wpts = XmlEdit.children (waypoints_node xml_tree) in
   let node = List.find (fun w -> XmlEdit.attrib w "name" = wp#name) xml_wpts in
   let utm = utm_of WGS84 (wp#pos) in
-  let (dx, dy) = utm_sub utm utm0 in
-  XmlEdit.set_attribs node ["name",wp#name; "x",sof dx; "y",sof dy; "alt", sof wp#alt]
-
+  try
+    let (dx, dy) = utm_sub utm utm0 in
+    XmlEdit.set_attribs node ["name",wp#name; "x",sof dx; "y",sof dy; "alt", sof wp#alt]
+  with
+    _ ->
+      prerr_endline "MapFP.update_xml: waypoint too far from ref (FIXME)"
+      
 let new_wp = fun xml_tree waypoints utm_ref ?(alt = 0.) node ->
   let float_attrib = fun a -> float_of_string (XmlEdit.attrib node a) in
   let x = (float_attrib "x") and y = (float_attrib "y") in