A Chennai-bound Indigo flight was forced to make an emergency landing at Hyderabad’s Rajiv Gandhi International Airport on Sunday after a passenger’s power bank caught fire mid-air. The cabin filled with smoke and the crew had to extinguish the fire. Authorities have launched an investigation.A similar power bank-fire occurred in May. After touchdown, chaos erupted onboard a Chandigarh-bound Indigo flight after a passenger’s power bank exploded, initiating an emergency evacuation of passengers. The device was reportedly tucked into a seat pocket when it combusted, prompting the passenger to alert the cabin crew.The incidents once again raised concerns over the safety of lithium-ion battery-powered devices aboard aircrafts and the potential risks posed by power banks during flights. But what exactly causes these devices to erupt in flames?Why did the power bank explode on the Indigo flight?Power banks typically contain multiple lithium cobalt oxide (LCO) or lithium-ion battery cells, many of which may be low-quality, poorly manufactured, or even recycled. Experts say these batteries are highly energy-dense and therefore vulnerable to overheating and combustion under certain conditions.“Aircrafts typically experience a slight jolt during landing, which may have caused a mechanical vibration in the power bank. Combined with a fully charged LCO battery, this could have triggered an internal short circuit, eventually leading to the fire,” explained Sagar Mitra, professor at IIT Bombay, about the May incident.Also in Explained | What happens if lightning strikes an aeroplane?According to experts, internal leakages between a battery’s positive and negative terminals, manufacturing defects, or electrolytic discharge can also trigger such incidents. Electrolytic discharge refers to the leakage of gel or electrolyte material inside the battery, usually caused by physical damage, poor internal coating, or degradation over time.Certain user habits can further increase the risk. “Many people unknowingly overcharge their power banks or continue using damaged devices, which can make them unsafe,” said Vivek Panchal, MD of Powertron, a battery manufacturing company.Story continues below this adGenerally, it is recommended to keep the power bank’s state-of-charge (SOC) at 80% and avoid charging it to the maximum capacity. This helps reduce stress on the battery cells and extends their storage life.What do rules say about power banks aboard planes?Most airlines in India, including IndiGo, SpiceJet, and Air India, prohibit passengers from carrying power banks in checked-in baggage. However, such devices are generally permitted in cabin baggage under prescribed limits.“Power banks contain lithium batteries, which are prone to malfunction and combustion. Keeping them in the cabin ensures that crew members can immediately detect and contain any potential fire,” explained aviation expert Jai Rao. In contrast, if a battery fire were to occur in the cargo hold, it would be significantly more difficult to access, he added.In November 2025, the Directorate General of Civil Aviation (DGCA) issued a dangerous goods advisory prohibiting passengers from using or charging power banks during flights. The regulator also barred passengers from storing power banks in overhead bins, citing concerns that inaccessible devices could delay emergency response during a fire. Airlines were directed to make in-flight announcements educating passengers about lithium battery risks and preventive measures against short-circuiting.Story continues below this adThe advisory followed several similar incidents globally. In June 2024, a passenger’s power bank exploded aboard an Air Arabia flight from Abu Dhabi to Kozhikode, triggering panic among passengers. Later, in March 2025, a fire linked to a portable power bank severely damaged a South Korean aircraft before take-off.Concerns surrounding lithium-ion batteries are not new. In 2016, the International Civil Aviation Organization banned lithium-ion batteries from cargo shipments on passenger aircrafts following repeated warnings from pilots and aircraft manufacturers about fire hazards.What should passengers keep in mind when travelling with power banks?Apart from combustion risks, overheating is a major issue associated with power banks. Technicians say these devices should ideally be stored below 55 degrees Celsius. Most modern power banks are equipped with an inbuilt over-temperature cut-off feature operated through a battery management system (BMS), which protects against overcharging, excessive discharge, and overheating while monitoring battery health. Depending on the device, users can either manually configure this feature or rely on a smart BMS.Story continues below this adExperts advise consumers to prioritise battery life cycle, cell quality, and warranty while purchasing power banks. “Products with a higher Mean Time Between Failure (MTBF) or reliability generally have a longer and safer operational life,” Panchal said.Mitra added that users should cease using any power bank that overheats during charging or discharge. Visible swelling, leakage, unusual odours, or excessive heating are also warning signs that the device may be unsafe and should be inspected or discarded immediately