Flight Details
Aircraft Type: Airbus A320-214 Operator: TAP Air Portugal Registration: CS-TNK Flight Number: TP687 Route: Luxembourg Airport (LUX), Luxembourg to Francisco Sá Carneiro Airport (OPO), Porto, Portugal Date of Incident: 16 April 2025 Total Occupants: Not officially confirmed; typical A320 configuration for TAP is approximately 174 passengers with 6 crew Weather Conditions: Visual meteorological conditions on arrival, no adverse weather reported
Introduction
On 16 April 2025, a TAP Air Portugal Airbus A320-200 operating flight TP687 from Luxembourg to Porto encountered smoke in the cockpit during descent. The crew advised air traffic control of the situation while continuing the approach to runway 17 at Porto, where the aircraft landed safely. Emergency services met the aircraft on arrival. Two individuals were later transported to hospital due to smoke inhalation. The airline denied reports of smoke in the cabin and confirmed no fire occurred. The event has been classified as an in-flight smoke emergency involving cockpit air contamination and potential environmental system malfunction.
Sequence of Events
The A320 was nearing the end of its scheduled flight when, during descent into Porto, the flight crew reported the presence of smoke in the cockpit. Communications with ATC indicated an abnormal situation, but the aircraft did not declare a Mayday or request immediate priority handling.
Flight tracking showed a normal descent profile with no significant deviations. The aircraft maintained its planned arrival routing and made a straight-in approach to runway 17. Emergency services were placed on standby by Porto tower in response to the smoke report.
Upon landing, the aircraft exited the runway and was directed to a remote stand for evaluation by airport fire and medical personnel. The engines were shut down, and the cabin was disembarked under supervision. There was no evacuation via slides.
Portuguese Civil Protection initially reported fire and smoke onboard, stating that emergency response units were dispatched to treat affected individuals. However, TAP Air Portugal clarified that while there was smoke in the cockpit, there was no actual fire and no smoke present in the passenger cabin.
Crew & Communication
The flight crew identified the presence of smoke during descent, most likely either via visual confirmation or odour/sensory cues. Airbus cockpit systems include smoke detectors in the avionics bay and electronic centralised aircraft monitoring (ECAM) alerts for air conditioning, electrical smoke, or avionics bay smoke.
The crew relayed their condition to ATC but continued with a controlled descent and approach rather than initiating diversion or emergency descent procedures. The decision not to divert suggests that while the smoke was visible or detectable, it did not degrade visibility, instrumentation, or flight control functionality.
Crew resource management (CRM) was applied to ensure coordination between monitoring duties, systems checklist management, and descent navigation. ATC communications remained clear, and no distress signal was sent.
Cabin crew were likely informed, though no announcements were made indicating smoke in the cabin. Cabin conditions were reported as normal by the airline.
Aircraft Systems & Technical Analysis
The Airbus A320’s environmental control systems, which regulate cockpit and cabin air, are supplied by bleed air tapped from the engines or APU and passed through air conditioning packs. Smoke in the cockpit can result from:
Electrical short circuit or relay overheating Oil fumes entering bleed air ducting Avionics bay component overheating Failure of air conditioning components or recirculation fans
The aircraft continued flight and landed normally, indicating that critical systems such as pressurisation, flight controls, and electrical power remained operational.
Post-flight inspections would focus on avionics bay components, environmental control systems (ECS), and cockpit circuit breakers. The absence of a fire confirms that no open flame or combustion occurred, but the source of smoke—whether electrical, hydraulic mist, or oil-based—remains under investigation.
The aircraft remained grounded after landing pending technical inspection.
Passenger Experience & Cabin Conditions
According to the airline, no smoke was present in the cabin and the flight proceeded uneventfully for passengers. There were no reports of panic, oxygen mask deployment, or cabin crew distress.
Nevertheless, two individuals were transported to hospital for symptoms consistent with smoke inhalation. Their identities were not disclosed, though they were possibly flight crew or front-row passengers exposed to airflow from the cockpit environment.
Medical responders treated those affected on the apron. No evacuation or emergency disembarkation occurred, and standard procedures were followed to transfer passengers to the terminal.
Emergency Response & Aftermath
Porto airport emergency services responded immediately upon landing. Aircraft rescue and firefighting (ARFF) units met the aircraft on the taxiway and conducted external inspection before allowing ground crew to approach.
The Portuguese Civil Protection Agency initially indicated the presence of smoke in the cabin, later corrected by the airline. Fire units inspected the aircraft and confirmed no active fire, no thermal damage to the fuselage, and no structural impact.
Operations at Porto were not significantly affected, and no runway closures were reported.
TAP engineers initiated a ground inspection of the aircraft, which remained out of service at the time of reporting.
Investigation Status
Portugal’s Civil Aviation Authority (ANAC) and aviation safety investigators have been notified. TAP Air Portugal launched an internal investigation alongside aircraft manufacturer Airbus and maintenance teams.
Investigators are focusing on the cockpit ECS, electrical bus systems, and avionics bay condition. Inspection logs, CVR/FDR data, and maintenance history will be examined for any prior anomalies linked to ECS faults, odour complaints, or warning flags.
Initial evidence suggests the smoke may have originated from an environmental component failure rather than combustion or wiring faults.
No formal preliminary report has been issued, but the airline has cooperated fully with emergency services and public health authorities.
Root Cause & Contributing Factors
Pending official findings, the most likely source of cockpit smoke includes:
Overheating of an avionics component or cooling fan Contaminated bleed air supply due to oil seal leak Electrical short in the overhead panel, pedestal, or circuit breaker panels Fault in one of the recirculation fans introducing odorous fumes
Contributing factors may include high electrical system load during descent, maintenance action deferred in prior cycles, or environmental contamination from engine/APU bleed air during throttle transition phases.
There were no reported weather, operational, or human performance factors contributing to the event.
Safety Recommendations & Industry Impact
While no formal recommendations have been issued, this incident reinforces the importance of:
Accurate reporting of smoke origin and severity by aircrew Prompt but controlled response to non-fire smoke incidents Enhancing ECS filtration and bleed air monitoring systems
TAP Air Portugal is expected to review its checklist procedures and crew training for distinguishing between minor odours and active smoke, especially in descent phases where workload is high and ECS demand shifts.
If component failure is confirmed, Airbus or component OEMs may issue inspection or service bulletins to affected operators.
Conclusion
The TAP Air Portugal flight TP687 cockpit smoke incident highlights the operational challenges of managing environmental system anomalies at low altitude. The crew handled the situation with discipline, ensuring a safe landing while avoiding unnecessary disruption or escalation.
The event resulted in minor medical consequences but no damage or injuries, and will serve as a case study for cockpit ECS troubleshooting and communication during smoke events.
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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