B777-200
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Time Pressure; Troubleshooting; Situational Awareness
Aircraft Equipment Problem Less Severe
Flight Crew Diverted; General Maintenance Action
Aircraft; Procedure
We were at cruise when we noticed a Status message prompt. Normally Status messages are something like 'one loop of a dual loop fire detection system has failed and the system has automatically reverted to single loop detection.' Status message; in that case; is information only; you are good to continue. After all [the guide material] says 'After engine start; it is not necessary to check status messages because any message having an adverse effect on the flight and requiring crew attention appears as an EICAS alert message. Status messages are checked after engine shutdown to determine if maintenance action should be initiated prior to the next flight. ' Our intermittent Status message said 'ELEC STANDBY SYS' Well; that doesn't sound good for ETOPS Operations so we have a look at our QRH; MISC; ETOPS System Failures; which [has] a list of no-go EICAS 'Messages' and; there it is. QRH says 'For any EICAS message inflight; refer to the table for guidance. If the EICAS message is listed; ETOPS entry is not recommended; unless any listed proviso can be complied with.'My FO (First Officer) said 'Status messages are not EICAS messages. EICAS messages are Alert messages. We are not even required to look at Status messages until gate arrival.' We looked at the menu to see if ELEC STANDBY SYS is one of the many Electrical system EICAS Caution Alert message and there it is. My concern is why are we getting a Status and not an Alert message? It seems to me; we should be getting a Master Caution Light and an amber EICAS Alert message. I sent Dispatch a free text; emphasizing that we have a Status but not a Caution message. He acknowledged our message but didn't have anything else to say. I sent another free text and asked 'Are you saying it is both safe and legal to continue and enter ETOPS airspace?' He replied 'I think not; standby while I get [Maintenance] on the line.' [Maintenance] gets on and tells me it is a repeat item and not to enter ETOPS airspace. He said he is looking at our electrical system as we speak and it shows a failed CA (Captain)/FO Standby System Tie Relay. I found out later; [Maintenance] has access to a Boeing program that allows them to see certain systems while the jet is airborne. We had already looked at our Electric Synoptic and it was normal. We diverted to ZZZ; MX replaced the failed relay and we continued to ZZZ1. I'd still like to know why we got a Status message and didn't get a Caution message when a component had clearly failed with no automatic reversion like fire loops. I wonder how many times this jet has crossed the pond with crews ignoring the intermittent Status message. Not slamming the crews; our published guidance and training supports it. We don't have detailed schematics but; it is possible there are 2 identical cross-ties (redundancy) that serve the same function which would explain a Status message with loss of one and a Caution message with loss of both.If all Status messages are excluded from EICAS messages that affect ETOPS; that should be clearly stated in first paragraph of ETOPS System Failures in MISC section of QRH.
B777-200 Captain reported receiving what should have been an EICAS alert as a status message.