B737 Next Generation Undifferentiated
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition
Aircraft
At FL390 the autopilot kicked off and we noticed our heading; attitude; navigation system on both the Captain and F/O (First Officer) side went blank as well as standby HSI had off flags. We looked up and noticed the right IRS (Inertial Reference System) fault light was illuminated. At approximately 100 miles from [the departure airport]; we elected to turn back around and returned. We [advised ATC]; due to lack of navigation system and no heading information. I was getting no-gyro vectors from ATC as F/O ran the IRS fault checklist. Upon completing the checklist we were able to get an attitude and heading information back; however; we still were missing our navigation data. With help from ATC we were able to safely navigate back to [the airport] where it was VFR and landed uneventfully.
Upon level off at FL 390; the autopilot kicked off. As we looked at our instruments; we noticed that we had lost our attitude; heading; and navigation displays on both the Captain and FO's side. Our Standby heading compass had off flags and all we had for navigation purposes was our standby ADI (Attitude Director Indicator) and our Whiskey Compass. As we continued to investigate; we noticed we had a right IRS fault light and referenced the QRH for this problem. Due to the fact that we could not safely navigate and [the departure airport] was VFR; we elected to coordinate with ATC to return. We request no-gyro vectors back as we began to run the steps of the QRH. Upon completion of the QRH steps; we were able to get main ADI and heading display back on the Captain's side but still no navigation displays. The FO's side still remained blank until we put both IRS's to left as the last step in QRH. With the help of ATC and great crew coordination; we were able to land uneventfully.
While level at FL390; B737NG crew reported a failure of the right IRS which resulted in the loss of all navigation and flight instruments. After completion of the QRH checklist and recovery of flight display data the crew returned to the departure airport.