TK5904
1999-APR-07 · Near Ceyhan, Adana Province, Turkey

Turkish Airlines — Flight TK5904

Turkish Airlines Flight 5904, a Boeing 737-400 on a positioning flight to Jeddah, crashed into a field near Ceyhan nine minutes after takeoff from Adana. The aircraft entered a steep dive from an altitude of approximately 10,000 feet (3,000 meters) during a climb through severe thunderstorms. Investigators determined that the crew likely failed to activate the pitot-static anti-ice system, leading to erratic airspeed indications. The pilots became disoriented by the false data and were further distracted by the presence of panicked cabin crew members in the cockpit, ultimately losing control of the aircraft.

Aircraft
Boeing 737-400
Registration
TC-JEP
Phase
Cause
Souls on Board
6
Fatalities
6
Origin → Dest
Adana Şakirpaşa Airport (ADA/LTAF), Turkey → King Abdulaziz International Airport (JED/OEJN), Saudi Arabia
Report

Investigation Summary

The aircraft, named Trakya, had just completed a successful flight transporting 150 pilgrims from Jeddah to Adana. After a one-hour turnaround for refueling, it departed for a return positioning flight to pick up more passengers. The flight took off with a new crew (two pilots and four flight attendants) and around 10 to 15 tons of fuel. Before departure, the crew was warned of severe thunderstorms moving across the aerodrome. During the climb, the pitot tubes likely iced over because the anti-ice system was not engaged, a step missed during pre-flight preparations. This caused the airspeed indicators to provide false readings. The flight data and cockpit voice recorders indicated that the crew failed to cross-check other instruments to verify their actual speed and attitude. The situation was exacerbated by the entry of flight attendants into the cockpit, whose screaming and panic created a chaotic environment that hindered the pilots' ability to troubleshoot the instrument failure. The aircraft nosed over into a near-vertical dive, impacting the ground with such force that it created a large crater; while some sources report the depth as 15 meters, the Aviation Safety Network records it as 10 meters.

Final Conclusions

The investigation by the Turkish Directorate General of Civil Aviation (DGCA) concluded that the primary cause was the crew's failure to recognize the cause of erratic airspeed indications and their failure to use alternative cockpit instruments for recovery. Contributing factors included the probable non-activation of the pitot-static anti-ice system, severe thunderstorm activity, and the distraction caused by cabin crew presence in the cockpit during the emergency.

Photographic Evidence (1)

Turkish B737-400 TC-JEP c/n 25378 at Heathrow - this was sadly written off a couple of years later
© Stuart Jessup · Wikimedia Commons

Video Analysis

No video analysis linked for this case file yet.

Airframe & Maintenance

Airframe Hours
11,600
Cycles
6,360
Engines
CFM International CFM56-3C1

Systems & Failure Modes

i

Pitot-Static Anti-Ice System

Electrical heaters designed to prevent ice buildup on pitot tubes; failure to activate this system in icing conditions leads to blocked sensors and erroneous airspeed readings.

i

Airspeed Indicator (ASI)

Instruments that displayed erratic and false data to the pilots due to sensor icing, leading to a loss of situational awareness.

Interesting Facts

  • 01The aircraft was 3.8 years old at the time of the accident.
  • 02The impact created a crater 15 meters deep and 30 square meters in area.
  • 03The horizontal stabilizer was found 250 meters away from the main wreckage site.
  • 04The flight was a positioning flight with no passengers on board.
  • 05The cockpit voice recorder captured cabin crew members panicking inside the cockpit during the final moments.

Safety Actions & Advisories

Cockpit Discipline and CRM

The investigation highlighted the critical need for Sterile Cockpit procedures to prevent cabin crew from entering the flight deck during emergencies or critical phases of flight.

Location

Near Ceyhan, Adana Province, Turkey · 37.2000, 35.3500

Case File History

  1. CorrectionUpdated investigation summary.

Related Cases

Case ID · turkish-5904-1999Last updated · Filed

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