AirA FO 3-43 Command Guidance for CHECK NAV caution or own ship position/HUD discrepancy

Question 1

What should aircrew do is the EICAS CHECK NAV is displayed?

Answer 1

1) If IMC, establish flight reference to the PFD
2) If VMC, establish flight WRT PFD or visual attitude (HUD IRS Data is invalid)

3) To remove the erroneous info from the HUD, select the PRS on the HUD Mode
4) Select the MFD NAV > STS page, if hybrid solution is the only amber NAV source, then select another nav source.