Date: 201511
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Dusk
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Cruise
Airspace: Class A ZZZ
Aircraft component: Central Warning/Master Caution
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Human factors: Confusion; Distraction
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew Overcame Equipment Problem; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: While in cruise; without any warning the following alert lights illuminated: WINDSHEAR; SPEED BRAKES; GRD PROX (GS INHB). Only the left bulb of: PULL UP; CABIN ALT; Master Caution; EICAS ATC FAULT. At the same time: Captain's Altimeter spun continuously; First Officer (FO) Altimeter spun continuously; FO Airspeed went to zero. The autopilot did not disconnect. There were no tones/audible warnings. With the aircraft stable we attempted to figure out what was going on by referencing the QRH. After about 1 minute all lights extinguished and flight instruments returned to normal except for the FO Altimeter; which remained failed for the remainder of the flight. We contacted Dispatch via SATCOM and asked for Maintenance to join the conversation. After discussing; maintenance stated that something was wrong but couldn't identify a single system that might cause the problem. They checked and observed some work was done on the EGPWS over the weekend; but weren't sure what was going on. Maintenance stated they wanted to discuss further and might want to bring the airplane to ZZZ instead of ZZZ1. We determined that we could not remain in RVSM since we were operating via one ADC (failed FO Altimeter) and requested new fuel burn from Dispatch. I also asked Dispatch to bring Flight Operations (pilot) into the discussion on whether everyone agreed it was a good idea to operate the aircraft with possible altimeter and EGPWS issues into a high terrain; special qualification airport at night. SATCOM dropped off line several times which necessitated multiple calls; but an ACP was able to join the conversation. He initially thought we had a simple ADC failure and that we were concerned about the possibility of a second failure. When I explained that we were dealing with an unknown anomaly that had impacted both primary altimeters and potentially the EGPWS and asked if anyone had performed a Risk Assessment of redispatching into the previously described ZZZ airport; the response was we should be fine since we still had a standby altimeter. I had already determined; after conferring with the FO; that we were comfortable operating into ZZZ; but was disappointed that there appeared to be no process of performing a Risk Assessment for the operation. Although ZZZ2 is still being fully implemented into our operation; a process should be created so that when a change to a flight is being considered; before making the change; appropriately qualified people are brought into the decision process so that unintended risk is not allowed to negatively impact the safety of our operations.




Synopsis: While in cruise; the B767 crew received a number of apparently false alerts/warnings as well as failure of altimeters and one airspeed indicator. After a short period of time; most of the warnings disappeared although the First Officers altimeter remained failed. After consulting with the company; they decided to divert into an airport with good maintenance support.