SQ321 Final Report: Radar Issue May Have Left SIA Pilots Blind to Severe Turbulence

Why It Matters

Undetected radar failures can leave crews blind to extreme weather, increasing injury risk and exposing airlines to greater legal liability. The findings may drive industry‑wide upgrades to radar hardware, software, and pilot procedures.

Key Takeaways

• Radar likely missed fast‑forming storm, causing severe turbulence
• 0.36% of SIA 777 flights logged radar blank‑screen faults
• Other aircraft detected storm, avoided incident
• SIA revamps radar training; regulators eye airworthiness directives
• Liability could shift to equipment makers under Montreal Convention

Pulse Analysis

The SQ321 tragedy underscores a long‑standing blind spot in aviation weather detection: traditional radar systems struggle with rapidly developing, moisture‑poor storm cells. While pilots can adjust radar gain and display range, a sudden vertical cloud can outpace the sensor’s refresh rate, leaving crews unaware of dangerous updrafts. The incident, which left one passenger dead and 56 seriously injured, adds to a pattern of turbulence events that have prompted airlines to re‑examine how they interpret radar data and communicate threats to cabin crews.

Technical scrutiny points to the Honeywell RDR‑4000 line, suspected on the SQ321 aircraft, which has faced European regulator warnings for “under‑painting” anomalies that erase weather returns without triggering fault alerts. Ground tests often cannot replicate the extreme cold and high‑altitude conditions that cause erratic antenna scanning, making intermittent failures hard to diagnose. Recent German investigations revealed software glitches that misclassify genuine weather echoes, prompting Airbus to amend manuals for late‑stage radar detections. These findings highlight the need for more robust hardware diagnostics and real‑time image‑recording capabilities to capture fleeting radar lapses.

Regulators in Singapore and the United States are now weighing mandatory airworthiness directives, while SIA has already revamped pilot weather‑radar training and introduced predictive tools like SkyPath. The legal landscape may shift as the Montreal Convention allows higher damages when carriers fail to take reasonable precautions, potentially placing greater liability on radar manufacturers. Industry stakeholders are expected to accelerate upgrades to radar firmware, enhance maintenance procedures, and adopt broader situational‑awareness tools to mitigate the risk of similar turbulence‑related catastrophes.