altitude_mode is still undefined when FGAutopilot::update is
first run.
altitude_hold = false ; // turn the altitude hold off
auto_throttle = false ; // turn the auto throttle off
heading_mode = DEFAULT_AP_HEADING_LOCK;
+ altitude_mode = DEFAULT_AP_ALTITUDE_LOCK;
DGTargetHeading = fgGetDouble("/autopilot/settings/heading-bug-deg");
TargetHeading = fgGetDouble("/autopilot/settings/heading-bug-deg");
#define DEFAULT_AP_HEADING_LOCK FGAutopilot::FG_DG_HEADING_LOCK
// #define DEFAULT_AP_HEADING_LOCK FGAutopilot::FG_TRUE_HEADING_LOCK
+#define DEFAULT_AP_ALTITUDE_LOCK FGAutopilot::FG_ALTITUDE_LOCK
/**