Attitude Indicator / Standby Instrument Replacements

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.

Quite simply, it no longer makes financial or practical sense to maintain some analog instruments in your panel.

In conjunction with the availability and lower pricing of the digital attitude instrument announcements, the FAA 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:


The 3” ESI-500 by L3 Avionics mirrors most Primary Flight Displays presenting attitude, altitude, airspeed and slip data.  The ESI-500 includes an internal lithium-ion battery.  Options for terrain, Synthetic Vision and other NAV aids are available starting at a List Price of $4200.  All backed by a company that has been producing instruments for the aviation community for over 50 years.

SAI 340

The SAI 340 is also a four-in-one standby instrument with an internal battery that weighs less than 1 pound and is only 1.4 inches in depth.  According to Sandia, the instrument can be operated for up to 2 hours from the battery, in the event of aircraft power failure.  The List Price for the SAI-340 is $3595.


Mid-Continent Instruments SAM (Standby Attitude Module) is a 2 inch digital instrument with a unique 2 screen display.  Along with attitude, altitude, airspeed and slip information, SAM shows vertical trend and heading information as well.  SAM features an internal lithium-ion battery with up to 1 hour of operation in standby use.  Because of its additional functions and features, SAM has a List Price of $9973.

For more detailed information on any of these new digital instruments or guidance on replacing any original, analog instruments in your aircraft, please do not hesitate to contact SEA or visit

Please follow and like us:

Leave a Reply

Your email address will not be published. Required fields are marked *