B737-800 flight crew reported loss of HUD guidance in flight due to failure of Inertial Reference Unit #1. Flight crew continued the flight to destination airport without descending out of RVSM airspace as required by the flight manual.
Synopsis
B737-800 flight crew reported loss of HUD guidance in flight due to failure of Inertial Reference Unit #1. Flight crew continued the flight to destination airport without descending out of RVSM airspace as required by the flight manual.
Narrative
I was Pilot Flying (PF) during Captain (CA) OE. At rotation; I lost all Flight Guidance in the HUD and attempted to transition to my PFD. I lost all vertical and lateral guidance; Flight Director; Flight Path Vector; Magnetic Compass; Heading Bug; and Terrain on my PFD and ND. The Check Airman gave excellent assistance to make the quick turn on the RNAV SID. I got the aircraft leveled off around 12;000 ft. over the water and that's when we realized he had everything working - I transferred the aircraft to him and started diagnosing the problems. We noticed TCAS and XPONDER FAIL messages at this time. No Amber Lights were Illuminated. We attempted a Recall and nothing posted. I checked our PERF INIT page and realized the L IRS (Inertial Reference System) was blank and ran the checklist. IRS on R restored all my data until the approach in ZZZ. We continued our flight to FL300. Over ZZZ1; in RVSM airspace; we found a reference in the Flight Manual that required 2 IRSs. I requested a descent to FL280. I looked at all the IRS checklists and none had a note to exit RVSM airspace. We talked about it for about an hour and half before finding the FOM reference for RVSM. The checklist should include a note to exit RVSM or request relief from ATC. Can we add notes to checklists to exit RVSM or request relief if the failed system is required for RVSM?
Second reporter narrative
During cruise in RVSM at FL 300; we descended to FL280 due to a loss of 1 Primary Altitude Measurement System. During flight we had a loss of the L IRS which lead to a loss of a Primary Altitude Measurement System.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.