Overview
• Operator: Delta Airlines
• Aircraft Model: Boeing 717-200
• Registration: N993AT
• Flight Number: DL-2761
• Route: Detroit, MI (USA) → Kansas City, MO (USA)
• Date: 12 February 2025
• Occupants: Undisclosed
Incident Summary
Delta Airlines flight DL-2761, operated by a Boeing 717-200 (N993AT), was cruising at FL340, approximately 10 nautical miles southeast of Chicago O’Hare (ORD), Illinois, when the flight crew detected a burning or smoky odour in the cockpit.
As a precautionary measure, the crew decided to divert to Chicago O’Hare International Airport and executed a safe landing on runway 10C approximately 18 minutes after initiating the descent.
The aircraft remained on the ground for about 7 hours before re-entering service.
Sequence of Events
Cruise Phase
• The flight was enroute at FL340 when the crew reported a burning odour in the cockpit.
• The decision was made to immediately divert to the nearest suitable airport, Chicago O’Hare (ORD).
Descent and Landing
• The aircraft commenced a rapid descent and was given priority handling by Chicago ATC.
• The flight landed without incident on runway 10C at O’Hare approximately 18 minutes after the issue was reported.
Post-Landing Actions
• Emergency services were on standby but did not observe any visible smoke or fire upon landing.
• The aircraft was inspected by maintenance personnel before being cleared for service.
Airline and FAA Statements
• Delta Airlines confirmed that a smoky odour in the cockpit prompted the diversion as a precaution.
• The FAA is aware of the incident but has not yet announced any formal investigation.
Possible Causes and Technical Analysis
The source of the burning odour remains undetermined, but potential causes include:
1. Electrical System Issue
• Overheating of wiring or electrical components could produce a burning smell without visible smoke.
2. Environmental Control System (ECS) Malfunction
• Issues with the air conditioning packs, bleed air system, or cabin air filters could introduce fumes into the cockpit.
3. Engine Oil or Hydraulic Fluid Leak
• Leakage of engine oil (such as Mobil Jet II or HyJet hydraulic fluid) into the bleed air system is a known cause of odours in the cockpit.
4. Avionics or Insulation Overheating
• Overheating avionics behind the instrument panel or degraded thermal insulation could produce a burning odour.
Aircraft Status
• The Boeing 717-200 remained on the ground in Chicago for approximately 7 hours for inspections.
• After no major faults were detected, the aircraft was cleared for service and resumed normal operations.
Analysis and Safety Recommendations
Given the nature of the incident, Delta Airlines maintenance teams should:
• Conduct a thorough inspection of the electrical and environmental systems.
• Check for potential fluid leaks in the bleed air system.
• Monitor the aircraft for repeat occurrences before resuming long-haul operations.
• Evaluate flight crew oxygen mask protocols for odour-related incidents.
Cockpit odours can indicate serious underlying mechanical issues, and any recurrence should warrant a more in-depth investigation to prevent potential smoke or fire hazards in flight.
Disclaimer
This report is based on available information as of 13 February 2025. While every effort has been made to ensure accuracy, the completeness of the details cannot be guaranteed. If you are the rightful owner of any referenced materials and wish them removed, please email takedown@cockpitking.com.
