The names Raytheon and RTN are owned by the Raytheon Company. ST40 Compass Instrument - quick reference guide Normal operation SWITCH ON t Compass heading Times out to the Compass heading screen after 5 seconds. o Locked heading Course computer sets auto lock Off course alarm values _Course computer sets auto lock ' Alarm on/off -+o 3 seconds Auto locked heading o -+- o Momentary :i>| alarm level 4+ o -I o i- With Set alarm level screen displayed, press the O and O