L-1011 Navigation: VHF NAF (34-1/2)

The Lockheed L-1011 as two in depended VHF NAV systems. The control heads are not located as part of the center console, but are part of the glare shield (see image above). A four-position DME control switch is also provided (outlined). The DME control switch has the following functions:

1. STBY - permits audio reception but no search display 
2. NORM - permits reception of up to 200 NM 
3. OVRD - permits reception of up to 400 NM
4. TEST - provides the following interactions on the RDDMI within a 9 second period after pushing the spring loaded switch to TEST: a) DME fail flag, b) Four dashes followed by c) Four zeros