I would like to know how the AHRS work on Boeing 737 aircraft. If this aircraft (like every the other ones I guess) has an Inertial Reference System (IRS), composed of 3 accelerometers and 3 gyroscopes, what elements compose its AHRS? 3 accelerometers and 3 gyroscopes as well?


1 Answer 1


The 737 does not have a separate AHRS. Those functions are simply outputs from the two IRS's.

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(Source) 737 IRS panel.

ATT (attitude) mode selects the AHRS-only output of the IRS.

  • $\begingroup$ Thank you for this info! What I am actually trying to figure out is Boeing's flight management system's "architecture" i.e.: does it use GPS, does it use radio navigation, does it use AHRS, automatic compass, etc... Any idea about how I can find that out? $\endgroup$
    – traducerad
    Mar 9, 2017 at 17:10
  • 2
    $\begingroup$ @traducerad For a good description, check out this document from SmartCockpit.com. Flight Management and Navigation It's a bit long to try and summarize here. $\endgroup$
    – Gerry
    Mar 9, 2017 at 17:18

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