UK Air Accident Investigators Warn of EV Battery Risks

High-voltage battery systems in electric aircraft pose a lethal risk to accident investigators and first responders, the Air Accidents Investigation Branch warned in its Annual Safety Review for 2025. The AAIB received 783 occurrence notifications in 2025, up from 762 the previous year, and recorded 12 fatal accidents resulting in 18 deaths.

The only fatal commercial air transport accident of the year involved a Beechcraft King Air B200 at London Southend Airport (EGMC) in July, which resulted in four fatalities. The AAIB opened one formal investigation, 23 field investigations, 56 correspondence investigations, and 131 record-only investigations during the year, and supported 45 overseas investigations involving UK interests.

Nine safety recommendations (SRs) were issued by the AAIB last year, the fewest in at least the past decade, according to a historical chart in the report. Industry stakeholders delivered 96 proactive safety actions in direct response to AAIB investigations, without the need for formal recommendations.

Chief inspector Robert Balls, who took over the role in January, succeeding Crispin Orr, described the low recommendation count as a reflection of closer collaboration with stakeholders. “This reduction in SRs and increase in safety actions compared to last year reflects the importance of working closely with stakeholders in our investigations in order to deliver the best safety outcomes for aviation,” he wrote in the foreword.

The review also addresses two emerging concerns. The first is the risk posed by high-voltage battery systems to investigators and first responders at accident sites involving electric aircraft. The AAIB warned that batteries capable of producing 350 to 800 volts DC present lethal electrocution risks and can trigger thermal runaway: an uncontrolled chemical reaction producing intense heat and flame that is difficult to interrupt and can destroy evidence. The AAIB said it is developing protocols and training to mitigate these risks as electric and hybrid aircraft enter wider service.

Another concern is the use of artificial intelligence to support investigations. The AAIB has developed a proof-of-concept AI transcription tool, hosted on a secure, isolated server, that can process cockpit voice recorder audio without exposing protected data to external platforms. Early results indicated that the tool reduces the time required to prepare a fully verified transcript by about 50%, depending on recording quality.

Balls said the pace of technological change in aviation made adaptation essential. “I am committed to ensuring the AAIB continues to adapt to maintain a leading role in aviation safety by conducting thorough, timely, independent investigations that make a real difference to flight safety,” he wrote.