Several manufacturers continue to make strides in offering affordable digital, electronic replacements for original, traditional analog attitude indicator instruments (aka “horizons”). Most noteworthy are the instruments offered by Sandia Aerospace, L3 Avionics, and Mid-Continent Instruments. These OEMs have all released products that are not only reasonably affordable but offer higher reliability and some additional features over original, analog instruments. Believe it or not, most of these newer, electronic instruments are less expensive than the analog alternative. In some cases, buying a digital replacement might even be less expensive than the next overhaul on the analog instrument that you might currently have.


In conjunction with the availability and lower pricing of the digital attitude instrument announcements, theFAA has recently published a policy describing the acceptable methods of replacing analog attitude instruments with electronic replacements. In this policy, the FAA provides further background for the substantiation of replacing aging, analog instruments with more current electronic technology. These reasons may include:

• Costs to maintain
• Parts availability
• Reliability

The policy explains some of the acceptable and airworthiness methods of replacing primary attitude instruments. Some of these methods include:

• Replacement of a single function analog indicator with a single primary function electronic indicator (i.e. not interfaced to other systems such as autopilot or other systems)

• Replacement of vacuum, analog instrument with electronic instrument containing a dedicated standby battery

These are not the only methods and other installation conditions that must be met, but the point is that there are reasonable means and methods to upgrade to a more ideal, electronic instrument as a minor alteration in the aircraft.

A quick rundown of 3 highlighted electronic replacements shows some of the features and advantages of each:

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