Narrative:

AC arrived with left IRS (left inertial reference system) fault. Pilot debrief contained no useful information. Mechanics started an alignment 3X before a successful alignment achieved. They said this was SOP and signed off the fault. AC flew [first trip] uneventfully. I was PF (pilot flying) on [the second trip] leg; overhead ZZZ @ FL340; I was startled by the ap disconnect horn. I looked up at my screens and they were blank. I announced 'you got it' and the first officer (first officer) took over flying. QRH procedure IRS fault (left) accomplished. At the conclusion of the procedure; there was zero reference in the QRH to what the effect on our aircraft systems were. After a great deal of searching in the FM (flight manual); I found wrong information on what effect the failure had on remaining aircraft systems. 'Should either IRS fail; the IRS transfer switch is used to switch all associated systems to the functioning IRS.' and even a diagram that depicted the wrong information. What I found out during the course of the flight and not from [company] procedures; maintenance or dispatch was that we would have no ap (had to leave rvsm); no ab (auto brakes) and incomplete flight director guidance on my side of the cockpit. The threat here is that if we were going to a short field remote destination in difficult weather; the lack of this awareness would lead to flawed decision making about where to take the aircraft. All of this information needs to be known immediately after the non-normal is complete.in light of the lack of 737X MCAS (maneuvering characteristics augmentation system) information in our boeing driven manuals and there obvious impact on safety; I strongly advocate that we here at [the company] protect our passengers and crew by supplementing these procedures with more information to increase sa (situational awareness). Before you dismiss this suggestion off hand; see the attachment that my jump seater [from another airline with a different aircraft model] showed me after the flight. It is the [other company's] procedure for the same malfunction. Notice the same boeing procedure; however look at the end of the procedure: 'autopilots cannot be engaged. Auto-brakes are not available. Only one FD (flight director) is available for approach mode. If approach mode is desired for PF (pilot flying); turn off the other FD.'FYI: friend [from yet another airline] showed me their procedure. It is the same as ours; junk.

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Original NASA ASRS Text

Title: B737 Captain reported Inertial Reference System failure and flight manual did not state all effects of failure on aircraft systems.

Narrative: AC arrived with L IRS (Left Inertial Reference System) FAULT. Pilot debrief contained no useful information. Mechanics started an alignment 3X before a successful alignment achieved. They said this was SOP and signed off the fault. AC flew [first trip] uneventfully. I was PF (Pilot Flying) on [the second trip] leg; overhead ZZZ @ FL340; I was startled by the AP disconnect horn. I looked up at my screens and they were blank. I announced 'You got it' and the FO (First Officer) took over flying. QRH procedure IRS FAULT (L) accomplished. At the conclusion of the procedure; there was zero reference in the QRH to what the effect on our aircraft systems were. After a great deal of searching in the FM (Flight Manual); I found wrong information on what effect the failure had on remaining aircraft systems. 'Should either IRS fail; the IRS transfer switch is used to switch all associated systems to the functioning IRS.' and even a diagram that depicted the wrong information. What I found out during the course of the flight and not from [company] procedures; maintenance or dispatch was that we would have no AP (had to leave RVSM); no AB (Auto Brakes) and incomplete Flight Director guidance on my side of the cockpit. The threat here is that if we were going to a short field remote destination in difficult weather; the lack of this awareness would lead to flawed decision making about where to take the aircraft. All of this information needs to be known immediately after the non-normal is complete.In light of the lack of 737X MCAS (Maneuvering Characteristics Augmentation System) information in our Boeing driven manuals and there obvious impact on safety; I strongly advocate that we here at [the company] protect our passengers and crew by supplementing these procedures with more information to increase SA (Situational Awareness). Before you dismiss this suggestion off hand; see the attachment that my jump seater [from another airline with a different aircraft model] showed me after the flight. It is the [other company's] procedure for the same malfunction. Notice the same Boeing procedure; however look at the end of the procedure: 'Autopilots cannot be engaged. Auto-brakes are not available. Only one FD (Flight Director) is available for approach mode. If approach mode is desired for PF (Pilot Flying); turn off the other FD.'FYI: Friend [from yet another airline] showed me their procedure. It is the same as ours; junk.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.