L-1011 Flight Instruments: Central Air Data Computer (CADC)

The L-1011 has a fully electronic Air Data Computer system that replaced many analog systems except for the standby instruments. All in all, the flight instruments are driven by:

• Air Data Computers (ADC)
• Attitude Reference System 
• Heading Reference System 
• Instrument Comparator
• Radio Altimeter 

A total of four pitot/static probes are mounted on the L-1011.

• Two on the Captain's side (Capt. top, F/O lower).
• Two on the F/O side (F/Os top, Capt. lower)

Each probe senses both pitot and static pressure. There are no connections between pitot inputs. Cross over static sensing is provided for balance pressure sessions. Captain's and F/Os total air temperature probes are also provided.

All instruments which have traditionally been pitot/static are operated electrically by air data computers (ADC). ADC#1 provides data to the Captain's instruments and is sourced from the AC STBY BUS. ADC#2 provides data to the F/O's instruments and is powered form the Number 2 AC BUS. ADC#1 uses the Captain pitot/static and air temperature system and ADC2 uses the same system from the F/O. The basis inputs into to the ADC are not switchable, however, the ADC outputs can be switched between sides.