Flight Mode 6 disabled for Plane?

In the Mission Planner flight mode setup for Plane, the flight mode 6 option is disabled. Does anyone know why?

[attachment=0]Mission Planner Flight Modes.png[/attachment]

I looked at the source code and it is deliberate:

if (MainV2.comPort.MAV.cs.firmware == MainV2.Firmwares.ArduPlane ||
MainV2.comPort.MAV.cs.firmware == MainV2.Firmwares.Ateryx) // APM
updateDropDown(CMB_fmode1, “FLTMODE1”);
updateDropDown(CMB_fmode2, “FLTMODE2”);
updateDropDown(CMB_fmode3, “FLTMODE3”);
updateDropDown(CMB_fmode4, “FLTMODE4”);
updateDropDown(CMB_fmode5, “FLTMODE5”);
updateDropDown(CMB_fmode6, “FLTMODE6”);

    CMB_fmode1.SelectedValue = int.Parse(MainV2.comPort.MAV.param["FLTMODE1"].ToString());
    CMB_fmode2.SelectedValue = int.Parse(MainV2.comPort.MAV.param["FLTMODE2"].ToString());
    CMB_fmode3.SelectedValue = int.Parse(MainV2.comPort.MAV.param["FLTMODE3"].ToString());
    CMB_fmode4.SelectedValue = int.Parse(MainV2.comPort.MAV.param["FLTMODE4"].ToString());
    CMB_fmode5.SelectedValue = int.Parse(MainV2.comPort.MAV.param["FLTMODE5"].ToString());

[color=#BF0040] CMB_fmode6.Text = “Manual”;
CMB_fmode6.Enabled = false;
[/color] }

I’m able to set the value to something other than Manual for FLTMODE6 on the Full Parameters list screen. Is there a reason why Flight Modes forces 6 to be Manual?

It is deliberate to make sure you have “manual” as an option in case it all starts to go wrong.