An Air Canada Rouge Airbus A319 was forced to return to Toronto on 6 April 2025 following multiple intermittent instrument faults, VHF radio issues, and uncommanded aircraft movements in climb. The crew declared a PAN-PAN emergency and conducted a safe return. The cause was later traced to a defective Integrated Drive Generator (IDG).
Event Summary
Air Canada Rouge flight RV1878, operated with an Airbus A319-114 registered C-GBHZ, departed Toronto Pearson International Airport (CYYZ) at approximately 09:00 local time, bound for Hewanorra International Airport (UVF) in Saint Lucia with 115 occupants onboard. The aircraft was climbing through FL250 when the flight crew encountered multiple transient anomalies affecting critical flight instruments and aircraft control.
According to preliminary information, the Electronic Centralised Aircraft Monitoring (ECAM) system began displaying intermittent failure messages affecting:
Primary Flight Display (PFD) Navigation Display (ND) VHF radio systems Transient control inputs (uncommanded yaw and roll)
The aircraft also exhibited uncommanded lateral motion, described by the crew as yaw and roll oscillations, which necessitated immediate disconnection of the autopilot. The ECAM began generating caution messages, and the aircraft was manually controlled as the crew stabilised the situation.
In-Flight Emergency Declaration
As the aircraft continued to experience mild oscillations and continued loss of primary and navigation instrumentation, the flight crew elected to return to Toronto. During the return, they received a FAC 1 fault indication—related to one of the two Flight Augmentation Computers responsible for flight envelope protection and rudder/yaw control logic.
The crew performed the appropriate non-normal checklist and declared a PAN-PAN emergency, informing ATC of degraded systems and abnormal flight behaviour, but not a life-threatening situation. At this stage, yaw and roll oscillations had reduced in severity and subsequently ceased as the aircraft descended through FL170.
With the aircraft stabilised, and fault indications no longer active, the crew cautiously re-engaged the autopilot and coordinated an uneventful return to Toronto Pearson, landing on a standard approach with emergency services on standby.
Post-Landing Maintenance Action
Following the event, the aircraft was removed from service for inspection. On 2 May 2025, the Transportation Safety Board of Canada (TSB) issued a brief statement indicating that the Integrated Drive Generator #1 (IDG#1) was found to be defective. The IDG was subsequently removed and replaced.
The IDG is a critical component that mechanically drives an electrical generator via the engine accessory gearbox, ensuring constant frequency AC power to essential aircraft systems. A failure of the IDG can result in power fluctuations or loss to one of the aircraft’s AC buses, which in turn affects systems like the flight displays, radios, autopilot, and flight control computers.
In this case, the failure of IDG#1 likely caused erratic or transient electrical power supply to key avionics systems on AC Bus 1. This can explain the observed intermittent faults across PFDs, NDs, VHF radios, and associated fly-by-wire instability—particularly with the FAC system and yaw damper input logic.
Aircraft and Systems Background
Type: Airbus A319-114 Registration: C-GBHZ Engines: 2 × CFM56-5A5 Operator: Air Canada Rouge Delivery Year: 2001 (ex-Air Canada mainline)
The Airbus A319, like all A320 family aircraft, relies on a sophisticated three-bus electrical architecture consisting of AC and DC power sources. Critical components like flight computers (FAC, SEC, ELAC), displays, and communication radios are distributed across multiple buses for redundancy.
A single IDG failure should not ordinarily cause loss of control or flight instability, but in rare cases, spiking voltage, partial frequency failure, or AC bus transfer anomalies during IDG degradation can trigger cascading fault logic within digital systems.
The Airbus Flight Augmentation Computers (FACs) provide key functions including:
Yaw damping Rudder trim Turn coordination Flight envelope protection
Loss of FAC 1 input, in combination with electrical instability, can lead to transient uncommanded rudder movement and lateral control degradation—consistent with the reported uncommanded yaw and roll.
Crew Response and Safety Protocols
The crew’s decision to immediately disconnect the autopilot, declare PAN-PAN, and return while managing multiple ECAM faults reflects standard adherence to Airbus abnormal procedures. The decision to re-engage the autopilot only after stabilisation below FL170 and after fault cessation shows effective CRM and systems knowledge.
The use of the PAN-PAN designation (as opposed to MAYDAY) correctly categorised the situation as serious but not immediately life-threatening.
Operational Impact and Resolution
The aircraft remained out of service for approximately 11 hours following landing. Following IDG#1 replacement and ground testing, the aircraft was returned to line operations. No injuries or damage were reported, and no further system anomalies have been recorded since the event.
There has been no indication of wider fleet issues involving IDG units across Air Canada Rouge’s fleet or the Airbus A319 type generally.
Conclusion
This incident highlights the complex interdependence of electrical systems, flight control computers, and avionics in modern fly-by-wire aircraft. A single component degradation—such as an IDG—can initiate cascading system behaviour, affecting autopilot performance, control stability, and flight crew situational awareness.
Despite encountering multiple simultaneous technical anomalies at cruise climb altitude, the Air Canada Rouge crew demonstrated effective procedural discipline and systems management under pressure. The prompt PAN-PAN declaration, checklist execution, and safe return to base underscore the resilience of Airbus system architecture and the importance of robust crew training in handling electrical and control system faults in real time.
Disclaimer
This article is based on publicly available information and reports at the time of writing. While every effort has been made to ensure accuracy, we cannot guarantee the completeness of the information provided.
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