Aseman Airlines ATR 72-200 Crash – February 18, 2018

On February 18, 2018, an Aseman Airlines ATR 72-200 crashed into the Zagros Mountains, killing all 66 people aboard. The aircraft was en route from Tehran to Yasuj when it lost contact with air traffic control roughly an hour after takeoff. The wreckage was found in a remote, mountainous region, and recovery was hindered by difficult terrain and adverse weather conditions.

Flight and Weather Overview

The ATR 72-200 is a twin-engine turboprop designed for short to medium-haul flights. The aircraft involved, EP-ATS, had been in service for over 24 years. Although mechanically sound per pre-flight inspections, its advanced age raised concerns about its suitability for operating in challenging environments like Iran’s mountainous regions.

The flight departed Tehran’s Mehrabad Airport at around 08:00 local time. The weather at the time of the incident included low visibility, strong winds, and cloud cover, which likely affected the flight crew’s ability to navigate effectively in mountainous terrain. The combination of severe weather and mountainous terrain posed a significant risk, demanding higher situational awareness from the crew.

Terrain and Instrumentation

The Zagros Mountain range is notorious for its challenging terrain, especially in low-visibility conditions. The descent path toward Yasuj Airport requires precise altitude control, as pilots must navigate through mountainous areas while avoiding terrain obstacles. The absence of a functioning Terrain Awareness and Warning System (TAWS) on the ATR 72 was a critical factor in this crash. TAWS alerts pilots when an aircraft’s flight path is dangerously close to the ground, giving them time to take corrective action.

The lack of this modern system left the flight crew with limited terrain information. While traditional navigation aids provide general awareness, they are not as precise as TAWS in monitoring a rapidly changing flight environment. Without this critical alerting system, the crew had less ability to react to the rapidly changing terrain elevation.

Human Factors: Pilot Experience and Training

The ATR 72-200 was flown by a crew with varying levels of experience. The captain had substantial hours logged, but it was unclear how familiar both pilots were with the specific challenges of flying into Yasuj Airport, which is surrounded by high-altitude terrain. Even experienced pilots can find navigation in such an environment difficult without sufficient instrument guidance.

The investigation revealed that inadequate crew resource management (CRM) may have contributed to the crash. CRM is essential in complex flight environments, especially when decisions must be made rapidly. The difficult terrain combined with limited instrumentation may have overwhelmed the crew, leading to critical misjudgments in altitude and descent rates.

Technical Failures

While the ATR 72-200 has a robust design, the lack of modern safety features such as TAWS and the limitations of the aircraft’s older systems played a significant role in this accident. Additionally, while the investigation confirmed that the aircraft’s mechanical systems were functioning before departure, older systems are more prone to failure, especially under challenging environmental conditions.

The investigators also looked into the autopilot system to understand whether it was properly engaged and functioning during the descent phase. Modern turboprop aircraft like the ATR 72 use autopilot systems that are designed to maintain stable flight, but these systems must be closely monitored by pilots, particularly in mountainous areas.

Recovery and Analysis

After the crash, recovery teams faced immense difficulties reaching the crash site due to weather and terrain. The aircraft was found at an altitude of roughly 4,000 meters, scattered across the snow-covered mountainside. Black box data recovered from the wreckage provided crucial insight into the final moments of the flight.

Analysis of the cockpit voice recorder (CVR) and flight data recorder (FDR) revealed that the flight crew struggled with altitude management during the descent. The lack of situational awareness, compounded by low visibility and the absence of TAWS, likely prevented the crew from realizing how close they were to the terrain until it was too late.

Lessons Learned and Safety Improvements

The Aseman Airlines Flight 3704 crash highlighted several crucial lessons for both airlines and aviation regulators:

1. Terrain Awareness and Warning Systems (TAWS): The absence of TAWS on the ATR 72-200 was a significant factor. In response to this crash, airlines operating in mountainous regions should prioritize installing TAWS on all aircraft, regardless of age. Modern systems such as Enhanced Ground Proximity Warning Systems (EGPWS) could provide earlier warnings and better situational awareness.

2. Pilot Training and Familiarization: Pilots operating in challenging environments must undergo specialized training for terrain awareness and managing flights in low-visibility conditions. Enhanced CRM training can also help flight crews communicate more effectively and make critical decisions under pressure.

3. Weather Reporting and Flight Planning: The crash underscored the importance of accurate weather forecasting and real-time updates, particularly in mountainous regions where weather can change rapidly. Improved communication between air traffic control, meteorological services, and flight crews is essential to ensure safe operations.

4. Aircraft Modernization: Operating older aircraft presents challenges, particularly when they lack modern avionics and safety systems. While older aircraft can still be safe if well-maintained, upgrading key systems like TAWS, autopilot, and weather radar can dramatically reduce the risk of accidents in challenging environments.

Conclusion

The Aseman Airlines crash in 2018 serves as a sobering reminder of the importance of modern safety systems and specialized training for pilots operating in difficult conditions. The combination of challenging weather, difficult terrain, and the absence of advanced warning systems left the flight crew with few options. While human factors such as decision-making and experience played a role, the lack of critical avionics equipment was a decisive factor in the tragedy.

This incident spurred discussions within the aviation industry about the importance of ensuring that all aircraft, regardless of age, are equipped with up-to-date safety technologies. It also emphasized the need for specialized training for pilots flying into high-risk airports, where weather and terrain can create hazardous conditions.

In the aftermath of this crash, aviation regulators and airlines have continued to focus on improving safety standards, ensuring that all aircraft operating in such environments are equipped with the necessary systems to prevent future tragedies.