VMU

The VMU (Voice Messaging Unit) provides cockpit announcements on the E-10, E-11, P-13, A-4, W-6 and T-19. It requires cockpit power and completes its normal warm-up before speaking. Its announcements use the aircraft's installed cockpit voice.

Engine failure

“Engine one failure,” “Engine two failure,” or “Engine three failure” identifies an installed engine that has persistently failed to deliver its commanded output. The third-engine announcement applies to the E-10 and E-11; two-engine aircraft announce only engines one and two.

The discrepancy must persist for about one second. A continuing failure is announced once; confirmed recovery permits another announcement if the failure returns. Reducing the command to idle or deliberately shutting down for coast does not itself produce a failure call. A recovered failure waiting behind other speech is discarded.

This monitoring remains available on the ground, in hover, during atmospheric flight, ascent, suborbital or orbital flight, and re-entry, whether hand flown or under Autoflyte. It compares commanded and delivered output; it does not identify individual damaged parts.

Flap position confirmations

On the W-6 Manx and T-19, selecting a new flap detent produces a confirmation when the flaps reach it:

Flap position	Announcement
0°	“Flaps up.”
8°	“Flaps eight.”
20°	“Flaps twenty.”
30°	“Flaps thirty.”
40°	“Flaps forty.”

Default controls are Shift+F8 to extend one detent and Shift+F9 to retract one detent. Custom key bindings may differ. Confirmation applies in both directions and waits for actual position, so a lever movement or jammed flap does not by itself confirm the requested setting. Passing an intermediate detent on the way to a different selection does not announce that intermediate position.

Entering a cockpit or restoring valid flap information establishes the current position quietly. If another setting is selected while a confirmation is waiting to play, the old confirmation is discarded. These position confirmations remain available in flight and on the ground, including spaceflight; they are not an aerodynamic clearance to extend flaps.

Radio-height callouts

GPWS altitude advisories include “Three hundred” when descending through 300 feet (91.44 m) of radio height. This is height above the terrain beneath the aircraft, not MSL or pressure altitude. The existing “Minimums, minimums” priority at the default 200-foot decision height is retained, followed by the existing 100-foot call when applicable. Higher-priority alerts and valid sensor requirements still apply.

Mach callouts

The installed Catherine or Erin voice announces changes in the onboard Mach reading:

Transition	Announcement
Accelerating from below Mach 1 to Mach 1 or above	“Supersonic”
Decelerating from Mach 1 or above to below Mach 1	“Subsonic”
Accelerating from below Mach 5 to Mach 5 or above	“Hypersonic”

These automatic calls operate in flight through 100 km MSL and are inhibited above 100 km MSL. The limit uses altitude above mean sea level, not radio height or pressure altitude. It applies during hand flying and Autoflyte flight. There is no additional announcement when decelerating through Mach 5.

Crossing above the ceiling clears a waiting Mach announcement and stops one already playing. Returning below it establishes the current Mach quietly; only a subsequent Mach crossing produces a call. A crossing that happens in orbit is not replayed on re-entry. Entering a cockpit, restoring power or valid sensor information, leaving flight freeze, or entering or leaving the simulator also establishes a quiet baseline. Cockpit Mach callouts remain available in simulator flight for training.

Only the latest applicable Mach call waits for a voice slot, for up to three seconds. If a rapid change crosses both upward thresholds before a call can play, only “Hypersonic” is spoken. GPWS and TCAS warnings take priority and can interrupt Mach speech. The aural warning self-test plays all three recordings independently of the automatic flight thresholds.

Speech and self-test

Announcements share the cockpit speech queue. Ordinary queued announcements wait for the current phrase to finish; Mach callouts yield immediately to GPWS and TCAS warnings. Escape warnings take priority over waiting engine announcements; flap confirmations have lower priority. Power loss or a vehicle change clears stale pending engine and flap speech. Entering or leaving the in-world simulator also resets these pending calls; cockpit engine and flap monitoring remains available for training.

The default Shift+Scroll Lock binding starts or stops the aural warning test. It plays the recordings installed for that aircraft. Ctrl+Shift+Scroll Lock requests the separate TCAS test. GPWS has its own functional test and hazard controls.