HI ,
I have starting ArduPlane4.0.6 SITL with xplane ,but when i have disable the gps from parameter “sim_gps_disable” ,then i have no_fix in GS but i steel have correct location from the GPS 
.so i can’t test GPS loss situation. 
is there any thing that can in I do to really disconnect the GPS in the SITL?
best regard,
raj