Flight LX-1674 | Registration: HB-AZH
Date: 5 April 2025 | Location: Zurich Airport (LSZH), Switzerland
Flight Details
• Aircraft Type: Embraer ERJ-190-E2
• Engines: 2 × Pratt & Whitney PW1900G
• Operator: Helvetic Airways (on behalf of Swiss International Air Lines)
• Registration: HB-AZH
• Flight Number: LX-1674
• Callsign: SWR1674
• Route: Zurich (LSZH) to Florence (LIRQ)
• Date of Incident: 5 April 2025
• Total Occupants: 110 (103 passengers, 7 crew)
• Weather Conditions: Clear skies, dry runway, VMC
Introduction
On 5 April 2025, a Helvetic Airways Embraer ERJ-190-E2 operating as flight LX-1674 on behalf of Swiss International Air Lines rejected take-off on Zurich’s runway 28 due to a loss of braking capability. The aircraft, registration HB-AZH, had previously reported a technical fault during taxi and returned to the apron before making a second attempt to depart. Following a low-speed acceleration, the crew aborted the take-off and advised air traffic control that the aircraft was unable to vacate the runway due to brake failure. The aircraft remained on the runway until it was towed to a remote stand. No injuries were reported.
Sequence of Events
LX-1674 began taxiing for its scheduled morning departure from Zurich to Florence, holding short of runway 28 before the crew advised they were experiencing a technical issue. ATC instructed the aircraft to cross runway 28 at the threshold and return to the apron. A revised taxi clearance was issued and followed without further incident.
Roughly 20 minutes later, the aircraft re-established contact with the tower and confirmed readiness for departure. HB-AZH was cleared to line up on runway 28. During the early stages of the take-off roll, the aircraft initiated a low-speed rejected take-off. The crew notified ATC that the aircraft had lost braking capability and was unable to exit the runway without assistance.
Operations immediately suspended further departures from runway 28, and a tow vehicle was dispatched. The aircraft was removed from the active runway and positioned at a technical stand for inspection.
Crew & Communication
The crew acted in accordance with standard procedures by reporting the technical issue prior to the first departure attempt and returning to the apron. Upon reinitiating departure, no emergency was declared during the initial take-off roll; however, the crew’s prompt decision to abort and communicate the inability to brake effectively prevented further runway excursion or risk.
Tower communications indicate that the crew remained composed and transparent about the severity of the issue. No emergency squawk was activated. ATC ground coordination and immediate response helped ensure the situation remained under control.
While CVR and FDR data are expected to have captured cockpit dialogue and system readouts, no indications of panic, abnormal aircraft handling, or checklist deviation have been reported at this stage.
Aircraft Systems & Technical Analysis
The Embraer ERJ-190-E2 is equipped with electronically controlled brake-by-wire systems featuring anti-skid protection and redundancy across dual hydraulic systems. Braking performance is monitored through Brake Control Units (BCUs), which regulate pilot input and adjust brake force distribution.
The sequence of events suggests that a braking system fault—either electronic or hydraulic—was first detected during the initial taxi phase. However, the cause may have been deemed transient or cleared during diagnostic checks, allowing the aircraft to be released for a second departure attempt.
The subsequent low-speed take-off rejection revealed that brake performance was insufficient or entirely absent. Potential causes include:
• Faulty BCU response
• Hydraulic pressure loss in one or both systems
• Accumulator depletion or valve malfunction
• Electrical communication loss between brake sensors and the central control system
The failure rendered the aircraft incapable of performing standard runway exit manoeuvres, requiring external towing support. Engineering teams likely conducted a full inspection of hydraulic lines, pressure readouts, and electronic control units immediately following removal from the active runway.
Passenger Experience & Cabin Conditions
Passengers were reportedly calm during the sequence, with one occupant describing the event on social media as a low-speed rejected take-off followed by a wait onboard the aircraft. The captain issued a PA announcement explaining a brake issue, and cabin crew maintained order throughout the process.
There were no injuries, sudden braking events, or evacuation procedures. Passengers remained seated as the aircraft was towed from the runway. Although the rejected take-off caused a delay, the incident was managed without disruption inside the cabin.
Emergency Response & Aftermath
Zurich Airport temporarily suspended departures from runway 28 during the incident. Airside operations responded promptly by dispatching a tow tug and coordinating with the crew to reposition the aircraft.
There was no need for emergency services deployment, and no fire, smoke, or fluid leaks were reported. The aircraft was towed to a maintenance area and held for fault isolation and technical evaluation.
Flight LX-1674 was delayed or cancelled, and passengers were likely rebooked on later services to Florence. Runway operations resumed shortly after the aircraft was cleared from the active surface.
Investigation Status
No formal investigation has been launched by the Swiss Transportation Safety Investigation Board (STSB) at this stage. However, Helvetic Airways’ engineering department, under oversight from Swiss International Air Lines, is conducting an internal fault analysis.
System health monitoring data, crew reports, and cockpit recorders will be evaluated to determine:
• The nature of the fault detected during the initial taxi
• Whether proper diagnostics were carried out before the second take-off attempt
• How the brake failure manifested during the final take-off roll
Manufacturer support from Embraer and BCU component vendors may be requested if systemic faults are suspected.
Root Cause & Contributing Factors
The incident likely resulted from an unresolved or misdiagnosed fault in the brake system, which may have been intermittent or insufficiently confirmed during earlier troubleshooting.
Contributing factors may include:
• An incorrect assumption of fault clearance
• A latent defect in one or more brake system components
• Potential procedural gaps in the release-to-service process
• Failure of redundant systems to engage during braking demand
The ERJ-190-E2 relies heavily on automated brake controls, and a single point failure in the communication or hydraulic interface could result in complete braking loss, particularly at low speeds where reverse thrust is not yet engaged.
Safety Recommendations & Industry Impact
This event highlights the operational risk of reattempting take-off following an unresolved or intermittent technical fault, particularly one involving critical flight control systems.
Recommendations may include:
• Enhanced brake system diagnostics prior to departure after a fault alert
• Prohibition of second departure attempts following any brake or hydraulic system return-to-apron unless full clearance procedures are completed
• Emphasis on brake system redundancy checks in dispatch and crew briefings
• Review of Embraer E2 brake system alerts and logic thresholds for false-clear indications
Operators may also consider incorporating conditional delay protocols to allow deeper technical evaluation before releasing aircraft that have reported safety-critical faults during initial taxi.
Conclusion
The brake failure and resulting rejected take-off involving Helvetic Airways flight LX-1674 was handled professionally and without injury or damage, but it raises significant concerns regarding fault confirmation, release procedures, and the reliance on digital brake control systems in the Embraer E2 fleet.
The redundancy built into the aircraft’s braking architecture prevented a runway excursion, but the inability to vacate the runway unaided underscores the need for cautious operational decision-making when resolving suspected technical issues. The outcome serves as a case study for improving response to on-ground systems failures and preventing recurrence under similar conditions.
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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