Poorly manufactured, faulty and misused lithium batteries and those which have not been protected against short circuit can experience something called ‘thermal runaway’. This results in them getting so hot that they can catch fire, explode and ignite other nearby batteries. If that were to happen on the flight deck it could significantly disrupt the operation of the aircraft and cause serious injury to flight crew. Similarly, if such an event occurred in the passenger cabin it could cause serious injury to a passenger or crew member. Accordingly, Controlled portable electronic devices (C-PEDs) are subject to safety design and operational standards.
C-PEDs with installed or external batteries taken on board the aircraft by the operator could include:
- Portable In-Flight Entertainment (IFE) units
- Electronic Flight Bag (EFB), including any associated additional batteries (e.g. power banks) which have been approved for use
- Automated External Defibrillator (AED)
- Point-Of-Sale (POS) equipment, e.g. credit card readers
- Portable WiFi routers that have been approved for use
- Portable electronic devices carried by the operator for sale on the aircraft during the flight or series of flights, such as power banks, portable speakers, etc.
The ICAO Technical Instructions for the Safe Transport of Dangerous Goods by Air (ICAO Doc 9284) set out safety requirements applicable to lithium battery powered devices carried aboard an aircraft by the operator for use on the aircraft during the flight or series of flights.
These requirements state:
- spare lithium batteries must be individually protected to prevent short circuits when not in use;
- conditions for the carriage and use of these electronic devices and for the carriage of spare batteries must be provided in the operations manual and/or other appropriate manuals.
Part 1; 2.2.1 of the ICAO Technical Instructions and AMC1.CAT.GEN.MPA.140 (f)(1) of Commission Regulation (EU) No 965/2012 on air operations, each require that:
- the cells/batteries contained in a C-PED (and any spares) must be of a type which meets the requirements of each test in the United Nations UN Manual of Tests and Criteria, Part III, subsection 38.3 - this is referred to as the UN38.3 tests.
Lithium cells/batteries of portable electronic devices carried by the operator for sale on the aircraft must also have passed UN38.3 tests, so operators should ensure that the inflight sales procurement process seeks and retains suitable evidence of this.
EASA AMC 20-25 “Airworthiness and operational considerations for electronic flight bags” section 6.2 sets out the evidence required to be collected and retained by operators to demonstrate that rechargeable lithium batteries used to power EFBs and any power banks used to recharge them during flight are acceptable. Operators should collect and retain evidence of the UN38.3 tests, plus one of three specified Underwriters Laboratory (UL), International Electrotechnical Commission (IEC) and Radio Technical Commission for Aeronautics (RTCA) tests.
Guidance on the response to an in-flight battery / PED fire / smoke event is provided within ICAO Doc 9481, Emergency Response Guidance for Aircraft Incidents Involving Dangerous Goods.
In summary, this recommends:
- applying the fire-fighting procedure to knock down any flames
- dousing the device with water or other non-flammable liquid
(aimed at cooling to prevent thermal runaway propagating to adjacent cells)
- leaving the device in its place and monitor for any reignition (approximately 10 to 15 minutes)
- completely submerging the item in water and secure the container
- monitoring the device and the surrounding area for the remainder of the flight
Specifying a period before an item can be moved and be rendered completely safe recognises that a lithium battery may reignite. This is because water tipped onto many PEDs such as laptops or tablets may not reach the battery compartment and in turn, this may be insulated by the surface the PED is sat on, for example a seat back meal tray. On the flight deck, dousing an item with water may be difficult due to confined space and the water could potentially damage other electronic systems.
Since the development of the ICAO guidance, new products designed for use in response to lithium battery thermal runaway events have become available. Products which provide both a cooling and containment capability are typically more aligned to the existing ICAO guidance as when used, they are filled with water or other non-flammable liquid to act as a cooling agent.
After knocking down flames, it could conceivably take just a couple of seconds for a PED to be placed inside a containment bag, allowing it to be moved to a place of safety. Passengers could then return to their seats mitigating potential unrelated safety hazards such as injury in the case of severe turbulence. Equally, the effect on flight crew in carrying out their duties following an event on the flight deck would be minimised.
Accordingly, fire containment bags may be used in response to an in-flight battery / PED event, providing that:
- the operator is satisfied that the manufacturer's product performance claims are legitimate;
- use of the selected product has been included in the safety risk assessment required under AMC2 CAT.GEN.MPA.140(c);
- emergency procedures have been amended to reflect use of the equipment;
- the crew dangerous goods training programme(s) has been revised and received re-approval by the CAA.