A321 flight crew reported partial failure of navigation systems followed by multiple electrical system faults during initial climb. Flight crew returned to departure airport and landed safely.
Synopsis
A321 flight crew reported partial failure of navigation systems followed by multiple electrical system faults during initial climb. Flight crew returned to departure airport and landed safely.
Narrative
On initial climb out from ZZZ; we experienced a series of sporadic malfunctions. Passing through approximately 7;000 ft; clean at 250 knots; we observed a navigation data disagreement between the CA and FO NDs (Navigation Display). With no immediate alert; a quick global assessment revealed NAV FM/POS DISAGREE on the MCDU (Multipurpose Control Display Unit). The CA side data appeared correct while the FO side was inaccurate; so I remained pilot flying.While attempting to troubleshoot without losing track of departure procedures; additional malfunctions occurred: AUTO FLT AP OFF; followed shortly by AUTO FLT A/THR OFF and thrust lock. At that point; we [requested assistance]; discontinued the climb; and requested vectors off the SID to clear traffic. The decision was based on three factors: (1) partial navigation failure; (2) insufficient time to confirm remaining navigation data integrity; and (3) being forced to hand-fly at low altitude on a SID out of a busy airport.Once vectored away as a priority aircraft; we continued to diagnose. The only ECAMs were automation-related; consistent with the original fault; and the status page confirmed both sets of automation were inoperative. We also noted NAV IRS (Inertial Reference System) 2 was blank and NAV IRS 3 was beginning to drift significantly. With the aircraft stable; no traffic or weather concerns; and handling priority; we began troubleshooting: checking circuit breakers; referencing applicable checklists; resetting the flight directors; etc. Despite the failures; the aircraft was flying normally; and the problem appeared contained.Given favorable weather and the availability of ZZZ; we elected to remain airborne to reduce fuel and avoid an overweight landing. I attempted to contact Dispatch via the crew phone on my iPad to conference with Maintenance Control; but the aircraft Wi-Fi proved inoperative. Progress continued; including notification of the FAs and passengers. An ACARS message and a detailed free-text message were also sent; though we received no response.Subsequently; further malfunctions occurred: FMS1/FMS2 POS DISAGREE on the MCDU and eventually a NAV IR 2 FAULT; resulting in unreliable navigation data on both sides. We then received GPS 2 FAIL. NAV IRS (Inertial Reference System) 2 remained blank; while NAV IRS 3 showed a drift of 77 miles.Given the progressive and expanding nature of these failures; it was clear the aircraft was experiencing a deeper electrical malfunction. I started the APU as a precaution in case the issue branched into power systems and elected to expedite the fuel burn. We increased drag; requested tighter vectors; and landed as soon as we were below maximum landing weight.After landing; I chose to vacate the runway and requested a safety vehicle inspection before taxiing to the gate as an added precaution. Almost immediately after touchdown; we then received NAV IR 2 + 3 FAULT. We taxied in and parked with no further issues. After briefing maintenance personnel; they were unable to immediately identify the problem. Several experienced team members remarked they had never seen anything like it before.Cause: Electrical malfunctions.
Second reporter narrative
On climb out from ZZZ around 7;000 feet; we noted a nav data disagreement between Captain and FO displays; with NAV FM/POS DISAGREE" on the MCDU (Multipurpose Control Display Unit). The Captain's side appeared correct. Shortly after; the autopilot disconnected; followed by autothrust disengaging and thrust lock. We requested priority handling; leveled off; and were vectored off the SID.At that point; I took over as pilot flying and handled ATC; while the Captain focused on troubleshooting. ECAM and the Status Page showed multiple automation faults; NAV IRS (Inertial Reference System) 2 was blank; and IRS 3 began drifting. The airplane itself remained stable and controllable.Given favorable weather and proximity to ZZZ; we held to reduce fuel below max landing weight while continuing to work the problem. The Captain attempted to contact Dispatch but was unable due to Wi-Fi issues. We updated the FAs and passengers and sent ACARS messages to dispatch without response.Failures continued to escalate (including FMS position disagree; NAV IR 2 fault; GPS 2 fail; and later NAV IR 2+3 fault after landing and taxiing clear of the runway). The captain started the APU as a precaution. Once fuel allowed; the Captain resumed PF duties for approach and landing and the Checklist was completed in order to make sure we hadn't missed anything.We landed without further issues; requested a runway inspection; and taxied to the gate. Maintenance was unable to immediately identify the cause.Causal / Contributing Factors:Progressive automation and navigation system failures created uncertainty in navigation data. Low altitude SID departure from a busy airport increased workload while hand-flying.Limited communication capability due to inoperative Wi-Fi hindered coordination with dispatch/Maintenance Control.Unprecedented system behavior and erratic ECAM messaging.Recommendations to Reduce Risk:Reinforce PF/PM role clarity during system failures to ensure effective division of flying; communication; and troubleshooting responsibilities.Include multi-system failure scenarios (IRS/FMS; autopilot; autothrust) in simulator training; especially at low altitude.Ensure reliable communication redundancy to maintain contact with Dispatch/Maintenance Control when Wi-Fi or ACARS is unavailable.Share this event internally as a case study to familiarize crews with progressive multi-system failures and recommended handling procedures."
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.