Assessment of the Risks Associated with the Handling and Transportation of Air Shipments Containing Lithium-Ion Batteries

Abstract

Air transport, in addition to passenger transport, also transports air shipments containing hazardous materials. Hazardous materials include lithium-ion batteries, which can be carried both by passengers and by cargo aircraft. Due to the dynamic development of lithium-ion power supply technology, many devices are equipped with batteries that threaten air traffic safety. The article presents the results of research based on FAA reports of incidents involving lithium-ion batteries. The article aims to present a risk assessment for transporting lithium-ion batteries. Due to the emergence of new devices containing batteries, it is essential to analyze their transport to minimize threats and eliminate aviation incidents. The observations and the analysis of FAA reports showed possible threats from the transport of lithium-ion batteries on board aircraft. The matrix method used indicated the level of risk of transporting lithium-ion batteries. The risk assessment showed the need to monitor or implement corrective actions while transporting flight-ion batteries. Possible solutions were also presented to increase the safety level of transporting lithium-ion batteries.

1. Introduction

Air transport safety is a priority, and emerging threats pose a significant challenge to ensuring this safety. Emerging technologies are not without their flaws, which may cause new threats to air traffic safety. There has been a noticeable increase in the use and transport of electronic devices containing lithium-ion batteries, which means that the number of units transported increases yearly, increasing the risk of dangerous situations. In the recent history of air transport, there have been several incidents involving, for example, hazardous materials, including the first spontaneous combustion of an electronic cigarette powered by a lithium battery in 2014 and information about defective batteries from one of the manufacturers of mobile phones [1]. Lithium-ion batteries are classified as hazardous materials under the International Civil Aviation Organization (ICAO) and the International Air Transport Association (IATA) regulations. Their transport requires the compliance with strict safety standards, but they still pose one of the greatest threats to air transport. Lithium-ion batteries stand out with several specific risk factors compared to other hazardous goods, such as flammable liquids, explosives, or radioactive substances. The first of these is thermal runaway [2,3], i.e., self-heating of the battery, which can lead to an uncontrolled chain reaction in which the temperature increases like an avalanche and causes ignition. The threat is even more significant in low-pressure and high-temperature conditions in aircraft holds [4]. Another factor related to the emission of flammable and toxic gases [5,6] may cause the release of flammable gases, increasing the risk of explosion in the cargo space.

Additionally, vibrations and shocks during flight can lead to micro-damage to the internal separators of battery cells, resulting in an internal short circuit and mechanical ignition. In the event of a fire or other dangerous phenomenon, it is not always possible to use immediate extinguishing methods because lithium-ion battery fires require specialist extinguishing agents. The identified threats have caused many restrictions from international aviation authorities. However, the emerging restrictions and recommendations regarding the transport of hazardous materials do not constitute a complete content due to the emergence of new devices belonging to hazardous materials [7].

According to ACI statistics, in 2021, global airports handled a total of 124 million tons of cargo [8], recording an increase after the pandemic. The most frequently transported goods include electronics, medical and pharmaceutical materials, valuable goods, and perishable products, such as food products. Goods or the components of these goods may fall into the category of dangerous goods, which affects the safe conduct of air operations [9]. To standardize the transport of dangerous goods, their classification, appropriate separations between individual types, and the need to strictly comply with appropriate segregation regulations were introduced [10].

The International Air Transport Association (IATA) develops and publishes standards on various aspects of aviation, offering various educational and training programs for aviation industry employees. One of the main goals of IATA is to increase the safety of air operations due to the increase in the transport of dangerous goods. IATA publishes the annual Dangerous Goods Regulations (DGR), a primary tool for all entities involved in transporting dangerous goods. The regulations developed by IATA cover a wide range of substances, such as chemicals, radioactive materials, explosives, gases, flammable liquids, and other materials that can cause damage if not correctly handled during air transport. The Lithium Battery Shipping Regulations (LBSR) is a manual created by IATA to enable the shippers of lithium batteries to ship their shipments in compliance with the safety requirements set by carriers and member states [11]. The LBSR contain provisions for the classification, packaging (e.g., package marking, labeling, transport documents), hazard communication, storage, and handling of all hazardous materials defined as lithium batteries. It is a collection of specific and individual provisions of air carriers and member states. An additional criterion is the presented tests for the types of lithium batteries and cells. The guide presents scenario-based situations presenting the mandatory requirements that the shipper must follow when shipping packages containing lithium cells and batteries in various configurations by air. The shipping instructions in this document refer to the legal requirements for the specific type, configuration, and size of a lithium cell or battery as a collection of cells.

The article presents an analysis of hazardous materials, particularly lithium-ion batteries, due to the fact that each passenger may have them. Lithium-ion batteries are commonly used to power all kinds of electronic items. They are used in electric vehicles and provide power for small products such as unmanned aerial vehicles, laptops, cameras, power tools, and mobile phones. All cells and batteries are classified in the ninth hazard class according to the IATA DGR, i.e., they belong to the set of various hazardous materials.

The main research question concerns identifying the main factors posing a safety risk related to the air transport of lithium-ion batteries. It is followed by identifying activities and recommendations for actions aimed at minimizing these risks.

The paper is organized as follows: Section 1 introduces the research area question, indicating the important issue of transporting lithium-ion batteries by air. Section 2 reviews the literature on battery transport and related hazards and risk analysis methods used in the analyzed area. Section 3 contains an analysis of aviation events based on the FAA database, divided into the source of the hazard. This section also analyzes incidents divided into events caused by battery overheating, smoke, and fire. The authors also performed an analysis in terms of aviation events and the type of aircraft on which such events were recorded. Section 4 presents a risk assessment of handling lithium-ion battery cables based on the FAA database. Section 4 summarizes the research area and recommendations for transporting lithium-ion batteries.

2. Literature Review

2.1. Transport of Lithium-Ion Batteries

The hazard during the transport of lithium-ion batteries may be related to improper storage or transport. These actions can lead to fires, which in turn can have serious consequences. These situations should be minimized, and for this purpose, regulations are being created that limit the risk resulting from improper transport. The generally applicable regulations aim to ensure that the share of lithium-ion batteries transported by air is safe, minimizing the risk to the crew, passengers, aircraft, and the environment. Identifying and minimizing the risk associated with the transport of batteries by air and compliance with aviation regulations are essential aspects affecting the safety of air transport.

The authors conducted a detailed analysis of the international regulations concerning the air transport of lithium-ion batteries, with particular emphasis on the safety issues related to the transport of both new and used batteries [12]. The authors indicated that most of the recommendations and guidelines concerned new batteries; therefore, introducing similar requirements for the transport of used or degraded batteries was necessary. The authors conducted thermal and mechanical tests to assess the behavior of batteries under air transport conditions. The results of the tests were used to develop recommendations for the safe packaging and transport of these batteries, minimizing the risk of incidents during flight. The increase in the number of lithium-ion batteries from various electronic devices and electric vehicles poses challenges related to their safe transport for recycling or reuse. The authors conducted a literature review based on Chinese sources and presented research results based on the conducted experiments on the thermal runaway of single-cell and packed lithium-ion batteries [13]. The results showed that the higher the state of charge of lithium-ion batteries, the higher the risk of ignition and explosion. The experiments were conducted using one type of lithium-ion battery, which is the most common. The authors point out the complexity of this topic and suggest performing future studies on different types of lithium-ion batteries. Research work on the analysis of battery temperature increase has been the subject of many scientific studies [14,15,16,17]. Due to the threats, early warning and fire extinguishing technologies are important. The authors presented early warning methods and monitored elevated temperatures by examining acoustics, heat, force, electricity, and gas [18]. The authors suggest using early warning systems for different types of batteries and conducting a series of experiments on extinguishing agents. Battery research focuses on various issues, e.g., electrochemical properties [19], application from an industrial production perspective [20,21], and practical applications of sodium-ion batteries in the military [22]. Although the research concerns sodium-ion batteries, the presented conclusions and methods can be valuable in developing procedures for transporting and storing lithium-ion batteries, especially in a military context.

2.2. Risk Assessment Methods in Air Transport

Safety in air transport is the most crucial aspect. The introduced Safety Management System (SMS) concerns risk management and ensuring the effectiveness of its control by all aviation entities. Risk analysis is one of the key tools for ensuring safety, and it is conducted following the principles described in SMS and implemented at airports [23]. The human factor is the most frequently indicated cause of safety threats at airports in the analyzed research works [24,25].

SMS is a systemic approach to safety management [26]. The SMS structure was designed to improve the level of safety by identifying threats, collecting and analyzing data, and assessing risks. Implementing and maintaining SMS is necessary in aviation organizations, institutions providing air traffic services, and others [27].

Risk assessment methods are essential to identify threats and then minimize or completely eliminate them [28]. The conducted risk assessment indicates whether this does not disqualify the carriage of lithium-ion batteries on board aircraft and whether the process of observation and continuous striving to improve the discussed solution is a sufficient preventive solution.

The risk matrix is a graphical way of presenting the assessment of the level of threat and risk using a matrix [29]. Its operation prioritizes and classifies the sources of the occurring threat and its associated effects. It is a tool for further discussion of the problems present in the process and how to solve and prevent them. The Safety Management Manual defines a risk management process model based on risk analysis. For this purpose, the identified threat is assigned an estimated probability (

Table 1. Probabilities of safety risks.

Value	Probability	ICAO Description	FAA ARP
1	Extremely improbable	Almost inconceivable that the event will occur	Expected to occur < every 100 years
2	Improbable	Very unlikely to occur	Expected to occur once every 10–100 years or 25 million departures, whichever occurs sooner
3	Remote	Inlikely to occur, but possible	Expected to occur about once every year or 2.5 million departures, whichever occurs sooner
4	Occasional	Likely to occur sometimes	Expected to occur about once every month or 250,000 departures, whichever occurs sooner
5	Frequent	Likely to occur many times	Expected to occur more than once per week or every 2500 departures, whichever occurs sooner

Source: [26].

) and risk severity (

Table 2. The severity of safety risks.

Value	Probability	ICAO Description	FAA ARP
A	Catastrophic	Equipment destroyed Multiple deaths	Complete loss of aircraft and/or facilities or fatal injury in passengers(s)/worker(s); or Complete unplanned airport closure and destruction of critical facilities; or Airport facilities and equipment destroyed
B	Hazardous	A large reduction in safety margins, physical distress or a workload such that the operators cannot be relief upon to perform their tasks accurately or completely Serious injury Major equipment damage	Severe damage to aircraft and/or serious to passenger(s)/worker(s); or Complete unplanned airport closure, or Major unplanned operations limitations, or Major airport damage to equipment and facilities
C	Major	A significant reduction in safety margins, a reduction in the ability if the operators to cope with adverse operationg conditions as a result of an increase in workload or as a result of conditions impairing their efficiency Serious incident Injury to persons	Major damage to aircraft and/or minor injury to passenger(s), or Major unplanned disruption to airport operations, or Serious incident, or Reduction on the airport`s ability to deal with adverse conditions
D	Minor	Nuisance Operating limitations Use of emergency procedures Minor incident	Minimal damage to aircraft, or Minor injury to passengers, or Minimal unplanned airport operations limitations, or Minor incident involving the use of airport procedures
E	Negligible	Few consequences	No damage to aircraft but minimal injury or discomfort of little risk to passenger(s) or worker(s)

Source: [26].

) on a five-point scale.

Table 3. Safety risk assessment matrix.

Risk Probability	Risk Severity
	Catastrophic A	Hazardous B	Major C	Minor D	Negligible E
Frequent 5	5A	5B	5C	5D	5E
Occasional 4	4A	4B	4C	4D	4E
Remote 3	3A	3B	3C	3D	3E
Improbable 2	2A	2B	2C	2D	2E
Extremely improbable 1	1A	1B	1C	1D	1E

Source: [26].

shows a matrix presenting the risk level assessment based on three tolerance levels: unacceptable in red, tolerable in yellow, and acceptable in green.

The risk matrix provides the basis for conducting a deeper analysis of the existing problem. This method supports taking further steps regarding the level of acceptability of the threat [30].

The risk matrix method is suitable for assessing the risk of handling hazardous materials at an airport for several reasons. First, it is intuitive and easy to use, enabling the rapid identification and assessment of hazards related to hazardous materials, even in a complex operational environment. The matrix effectively prioritizes preventive and mitigation actions by assigning risks to categories based on their likelihood of occurrence and potential impact.

Additionally, the method promotes collaboration between different teams, providing a visual representation of risks in a way that is understandable to all stakeholders, including managers and technical operators. The simple structure of the matrix also allows for regular updates of the risk analysis in response to changing operational conditions, such as an increase in air traffic, changes in procedures, or the emergence of new types of hazardous materials.

In summary, the risk matrix method is a versatile, effective, and practical tool for managing the risks at an airport, enabling the rapid identification of priorities and taking effective actions to minimize the risks related to handling hazardous materials.

Risk analysis methods can be divided into quantitative and qualitative [31] and probabilistic [32]. The system related to risk analysis and assessment is based on the definition of safety performance indicators [33]. Indicators are created to describe the number and frequency of aviation events and operational safety assessment [34]. Other methods that can be cited are based on data analysis [35], Bayesian networks, and Petri nets [36].

In summary, the analyzed works provide valuable information on various aspects of the safety of transporting lithium-ion batteries. They include both experimental studies and literature reviews, focusing on identifying potential threats and proposing solutions to minimize the risk during the transport of these batteries. The article conducts a risk assessment of lithium-ion battery transport based on the FAA data analysis. The research results may be important for air operators and regulatory bodies (ICAO, IATA, FAA) to implement more effective countermeasures.

3. Analysis of Lithium-Ion Battery Transport Incidents

3.1. Federal Aviation Administration Incident Reporting

Lithium-ion battery incidents were analyzed based on the Federal Aviation Administration FAA’s incident database. This database is maintained continuously and shows detailed incidents. According to the FAA, between 3 March 2006 and 14 August 2024, 496 incidents (related to lithium-ion batteries) were recorded in the United States or on board aircraft bound for or from the United States [37]. These incidents primarily involved events involving extreme overheating, smoke, or the ignition of items powered by lithium-ion batteries.

This article relies on incidents recorded in the FAA database because the database contains detailed information about these events, is maintained continuously, and is available. The study was based on the analysis from 2018 to 2023 because recent years are most likely to reflect actual data due to the increase in the number of battery-based devices shipped.

The study and data used focus on incidents conducted by the FAA, which has both advantages and limitations. The FAA maintains one of the most detailed databases of aviation incidents, but its scope is mainly limited to the airspace of the United States and airlines operating in that area. However, it should be noted that aviation is global and ICAO regulations, as the global body, set the standards for air transportation. The FAA enforces more stringent regulations than ICAO, so these data can be considered a valuable source of data. Additionally, the FAA has a high level of incident reporting compared to other regions where regulations are less stringent or reporting practices are less structured.

An analysis was conducted of incidents related to the transport of lithium-ion batteries registered in the United States by the Federal Aviation Administration. Based on the data published by the FAA, the incidents were divided into five categories, which are the sources of incidents [37]:

-

E-cigarettes.

-

A portable computer.

-

Battery pack.

-

Mobile phones.

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Other electrical devices.

The second division is the effect, i.e., the effect related to the specific device [37]:

-

Overheating.

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Smoke emitted from the device.

-

Fire.

The analysis was carried out with a division into the abovementioned categories in the years 2018–2023. The study included events taking place throughout the year; therefore, data from the 2024 swarm were not included. In 2020, the COVID-19 pandemic broke out, which resulted in limited air traffic. Passenger traffic was close to zero passengers, but freighter traffic continued with less freight transported.

3.2. Analysis of Incidents Involving Lithium-Ion Batteries

3.2.1. Incidents Caused by Battery Overheating

Figure 1 shows the quantitative distribution of incidents caused by overheating. The overheating incident itself is the least dangerous type of threat. Overheating detected at an early stage and reported to the service or appropriate personnel can be removed without interfering with the further course of the flight operation. In the years from 2018 to 2020, overheating was identified in few cases (Figure 1). In 2022, an increase in incidents related to e-cigarettes was noted. In 2023, a more significant number of incidents related to battery packs and mobile phones were recorded.

3.2.2. Smoke-Related Incidents

Figure 2 shows the distribution of quantitative incidents resulting from identified smoke emissions.

The highest number of incidents was recorded in 2018. Taking action to minimize the risk resulted in a decrease in the number of incidents in the period of 2021–2023. It should be noted that the battery pack remains at a similar level, which should result in additional rules, procedures, or restrictions.

3.2.3. Fire Incidents

Figure 3 shows the number of fire incidents. There is a significant increase in the number of incidents ending with fire compared to other categories.

In Figure 3, it can be seen that the battery pack category accounts for the largest share of incidents. In 2023, there was a decrease in the number of incidents due to fire. E-cigarettes caused no incidents. Although 2020 was the year of the COVID-19 pandemic, incidents related to e-cigarettes and battery packs were recorded. It can be said that 2020 was full of incidents that were more serious in terms of consequences than in previous years. This was certainly related to the greater share of cargo traffic. Shipments containing a large number of lithium-ion batteries are more difficult to control in the event of related incidents.

3.2.4. Summary of Incidents Involving Lithium-Ion Batteries

To sum up, it can be seen that the largest number of incidents were identified in 2018 (Figure 4). Despite the many actions taken, several dozen incidents were also recorded in 2023, most of which were caused by fire.

Figure 5 shows the total number of incidents in each category. Most incidents were caused by smoke and fire related to battery packs. The e-cigarette category also records incidents caused by overheating, smoke, and fire.

3.2.5. Description of Selected Incidents Involving Lithium-Ion Batteries

For air carriers, data on incidents involving lithium-ion batteries are extremely important from the point of view of the procedures implemented to minimize the risk of an incident. Incidents related to the carriage of lithium-ion batteries occurred on board two aircraft types, i.e., passenger and freight.

The first aircraft type is passenger planes, which mainly target their services to passengers. The aircraft’s upper deck is intended for passengers, while the lower deck is used to transport passengers’ baggage. Air carriers use the excess space available in their luggage for the transport of air freight. In the case of short-range narrow-body aircraft such as the Embraer 175, the available space for transport cargo is 500 kg, and in terms of volume 3 CBM. In the case of another very popular narrow-body passenger aircraft, the Boeing 737 MAX, it is possible to load 1500 kg, or 12 CBM volume. The possibilities change in the case of wide-body passenger aircraft. One of them is version 8 of the Boeing 787, and the longer one, version 9. In the case of long-range wide-body aircraft, passenger baggage and cargo are loaded into ULD units, which are then placed in specially arranged positions in the cargo hold to properly balance the aircraft and maximize the use of the available space.

Passenger baggage is placed in AKE containers, and most of the cargo is placed on PMC or PAJ pallets. The 787-8 version of the Dreamliner can take on board up to seven PMC pallets loaded with air freight or mail. The 787-9 version of the Dreamliner is longer than its predecessor, thanks to which it can take more passengers on board, which also translates into more space in the cargo hold. In this case, it is possible to load up to eight PMC pallets. The Boeing 787-8 and 787-9 have the capacity to lift around 11–12 tons of cargo and mail. The exact data depend on the number of passengers carried on a given flight and the amount of luggage that they carry. Passenger luggage is a priority over air freight. In this case, the cargo is built on the previously mentioned air pallet units (ULDs), i.e., it is grouped into large groups of cargo, in accordance with the principles of segregation and IATA regulations. Various dangerous goods, such as lithium-ion batteries, can be transported in such cases. Compared to batteries carried by passengers, the type and number differ.

A passenger may take lithium-ion batteries in electronic devices or as spare batteries on board the aircraft as follows:

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Batteries with a capacity of up to 100 Wh or up to two grams of lithium content—in this case, the carrier’s consent is not required.

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Up to 15 devices with batteries of up to 100 Wh in checked baggage or hand luggage.

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Up to two spare batteries with a capacity of over 100 Wh, but not more than 160 Wh, in hand luggage only.

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Up to 20 replacement batteries with a capacity of up to 100 Wh, in hand luggage only.

Batteries with a capacity above 160 Wh may be transported on board passenger aircraft only as a previously reported, registered transport of hazardous materials in accordance with specific regulations and IATA DGR requirements, which comes down to sending appropriately prepared equipment, in special packaging and marking, which is organized by companies specializing in the transport of DGR.

3.2.6. Incidents and Aircraft Type

Goods are mainly transported on board cargo aircraft, the so-called freighters. Such aircraft are designed to transport only goods. In this case, there are less restrictive rules for the transport of lithium-ion batteries. Cargo aircraft, such as the Boeing 777-200 Freighter operated by Qatar Airways, which operates twice a week to Warsaw Chopin Airport in the winter season, have 27 positions on board for cargo units, which translates into the possibility of taking about 100 tons of goods. A significant part of dangerous goods and lithium-ion batteries transported by air are transported on board cargo aircraft.

Figure 6 shows the percentage distribution of incidents by aircraft type. Identified incidents were recorded on board cargo aircraft in about 10% of cases. However, significantly more incidents were recorded on board passenger aircraft, which amounted to from 24% to even 50%. The specificity of cargo aircraft and the freight loading method differs from that of passenger aircraft. Due to the appropriate construction of ULDs, goods are properly segregated and loaded in a way that optimizes space and the level of safety. The goods are less exposed to continuous use but are exposed to a number of other tests. In the case of incidents involving cargo aircraft, we are able to conclude that they occur much less frequently, but they pose a greater threat due to the greater force of destruction. Lithium-ion batteries in large clusters lead to subsequent spontaneous combustion, which is a challenge for airport services aimed at extinguishing the fire or other actions.

It should also be emphasized that passenger planes have a significant advantage over freight planes, hence the observed difference. The number of incidents involving passenger planes is about 3.72 times more than for cargo planes. This is related to the large number of devices based on lithium-ion power that passengers carry in their hand luggage. The largest part of this type of device are mobile phones, which every passenger or member of the aircraft crew owns. In addition to mobile phones, many devices such as laptops or tablets are carried, which are powered based on the same principle as cells. A new device has appeared over the last few years, particularly posing a threat. This device is e-cigarettes, which, due to their youth in technology, are not a sufficiently well-researched and tested type of device. Due to the insufficient certification processes for e-cigarettes, there are many related incidents. Each of the mentioned devices is exposed to many external factors directly affecting their safety and proper functioning on board aircraft. Devices of this type can also lead to spontaneous combustion due to an incorrect certification process or its complete lack caused by the origin of the batteries from inappropriate sources, the so-called black market. Many incidents are caused by mechanical incidents, which unaware passengers can cause by dropping, hitting, or jamming the device between seats. These incidents also take place in the luggage compartments above the passenger seats. A device powered by a lithium-ion battery, even properly and safely stored in luggage, can lead to a situation that poses a threat to safety after being hit by other luggage.

4. Risk Assessment of Handling the Transport of Lithium-Ion Batteries

4.1. Identification of Groups of Causes of Incidents

In the risk assessment of the occurrence of a hazard during the transport of lithium-ion batteries, it is necessary to identify the existing hazards. For this purpose, the presented analysis based on FAA reports was used. The study of lithium-ion battery incidents shows problems concerning the entire aviation industry. The analysis of FAA data made it possible to define and create five main groups of causes of incidents. The groups of causes of incidents and the numerical and percentage share are presented in

Table 4. Identified groups of incident causes.

Name	Number of Incidents	[%] of Incidents
Self-combustion/overheating	179	65.32
Passenger/agent lack of knowledge	38	13.86
Damage due to a passenger’s fault	29	10.58
Damage during handling	22	8.02
Mechanical damage due to falling	6	2.18

Source: own study based on FAA [37].

.

Based on FAA reports, the following events were identified: of the incidents occurring in the years 2018–2023, only three ended with the evacuation of passengers from the aircraft (during boarding or before the taxiing procedure), constituting 1.09% of all incidents. Four times, the aircraft was returned to the departure airport, which constituted 1.45% of all incidents. Twice, the aircraft was returned to the parking position during the taxiing procedure before takeoff, and twice its part was damaged (e.g., the carpet in the passenger cabin), which occurred in 0.79% of the recorded incidents in the years 2018–2023 incidents involving lithium-ion batteries. On one occasion, a passenger suffered an injury as a result of a lithium-ion-battery-powered device catching fire in the form of burns (0.36% of incidents).

The analysis showed that the number of incidents disturbing the proper conduct of the flight operation was 4.37% of all dangerous situations. All of the 12 dangerous situations belonged to the group of threats resulting from spontaneous combustion/overheating of the device. This was the only group in which more serious incidents occurred.

4.2. Identification of Hazards in Handling and Transporting Batteries

Based on the analysis and industry knowledge, the 14 most common hazards in the process of transporting lithium-ion batteries by air were identified (

Table 5. Identification and classification of types of threats.

	Name	Threat Group
1	Mechanical damage (during the handling process, e.g., impact, being dropped by a forklift or a lifter).	Damage during handling
2	Mechanical damage caused by the passenger (in the passenger cabin, e.g., jamming the device between the seats, falling on the floor, or damage in the storage compartment).	Damage due to passenger’s fault
3	Thermal overload (spontaneous combustion, e.g., in the trunk during an air operation).	Spontaneous ignition
4	Thermal overload (exposure to harmful solar radiation during storage or handling).	Overheating
5	Battery overload (cracking/swelling).	Damage during the handling stage
6	Electrical overload (through deep discharge or the use of a faulty charger by the passenger).	Spontaneous ignition
7	Transport of batteries that do not meet the technical requirements—manufacturing defect (unknown origin of the battery and/or lack of certification).	Overheating
8	Lack of awareness of the presence of the battery in the device (about the possession/presence of the battery by the passenger and legal regulations).	Lack of passenger knowledge
9	Failure to declare the battery as DG (when sent by an agent).	Lack of passenger knowledge
10	Damaged shipment/battery (thermal escape, explosion, leakage, contamination). Exceeding the permissible limits per package or per passenger.	Lack of passenger knowledge
11	Carriage of devices not permitted for transport.	Lack of passenger/agent knowledge
12	Battery not protected against short circuit.	Lack of passenger knowledge or damage during the handling stage
13	Incorrect subcontracting on behalf of the air operator for handling Dangerous Goods.	Lack of passenger knowledge
14	Mechanical damage (during the handling process, e.g., impact, being dropped by a forklift or a lifter.	Lack of passenger/agent knowledge

).

The identification and sorting of types of hazards indicated that many of them occur due to the lack of knowledge of the passenger or ground handling agent. Several hazards resulted from damage during ground handling. The analysis of the causes of hazards should prompt entities responsible for safety to take actions to minimize similar incidents.

4.3. Hazard Identification and Risk Assessment in Battery Handling and Transport

In the next stage, hazards were identified, described, consequences resulting from it were indicated, and the methods of eliminating the hazard were described. An important element was to determine the hazard and assign it to a group in the risk matrix (

Table 6. Risk tolerance table for hazards related to air transport of lithium-ion batteries.

	Threat	Threat Description	Consequence	Risk	Threat Level	Methods of Controlling/ Eliminating the Threat
1	Mechanical damage	At the stage of the handling process, e.g., impact, dropping by a forklift or lift.	Withdrawal of goods from the shipping process.	4D	Tolerable	Audit processes and training of handling personnel.
2	Mechanical damage caused by the passenger	In the passenger compartment, e.g., the device is jammed between the seats, falls to the floor, or is damaged in the glove compartment.	Overheating resulting in smoke or ignition of the device.	5E	Tolerable	Proper awareness of the threat and warning of the consequences to passengers. Procedures for the crew in the event of an incident.
3	Thermal overload	Spontaneous combustion, e.g., in the trunk during an aircraft operation.	Fire on board the aircraft.	2C	Tolerable	Certified luggage racks with appropriate fire categories. Fire training for the crew.
4	Thermal overload	Exposure to harmful solar radiation during storage or handling.	Ignition resulting in damage to the batch of goods.	2D	Acceptable	Training in handling hazardous materials, subcontractor and operator procedures, audit.
5	Battery overcharge	Rupture/swelling.	Battery overheating.	4D	Tolerable	Procedures for the crew in the case of an emergency, certified racks with the appropriate fire category. Fire training for the crew and handling personnel.
6	Electrical overload	Due to deep discharge or use of a faulty charger by the passenger.	Overheating, smoke, or ignition.	5E	Tolerable	Emergency procedures for the crew, fire safety training for staff.
7	Transport of batteries that do not meet the technical requirements	Battery origin unknown and/or lack of certification.	Possibility of causing a thermal incident.	5D	Tolerable	Information on the website, sending memos to customers, reminder newsletters.
8	Lack of awareness of the presence of batteries in the device	About the possession/presence of batteries by the passenger and legal provisions.	Detection of the presence of batteries during security checks when scanning the device.	5E	Tolerable	Information on the website, sending memos to customers, reminder bulletins
9	Failure to declare batteries as DG	When dispatched by an agent.	Detection of the presence of batteries during security checks when scanning the device.	3E	Acceptable	Current control based on the detection of batteries in transported loads, verification of transport documents, security control, consignor’s declaration
10	Damaged shipment/battery	Thermal runaway, explosion, leak, contamination.	Pollution, environmental contamination.	4C	Tolerable	Aircraft fire systems, crew procedures in the case of an emergency, certified luggage with the appropriate fire category, fire training for personnel
11	Exceeding the permissible limits	Exceeding the permissible limits per parcel or per passenger.	Preparation of a rejection checklist or DGOR.	3E	Acceptable	Act on the transport of hazardous materials by air of 5 August 2022. Introducing the obligation for the sender to perform the following: (a) register with the Civil Aviation Authority as a SENDER. (b) Document training in the field of hazardous materials.
12	Transport of devices not approved for transport	Lack of verification of incoming goods.	Fire in the trunk without crew access.	4E	Tolerable	Verification of transport documents, security check, consignor’s declaration, preparation of an acceptance checklist.
13	Battery not protected against short circuit.	Electrostatic charge causing sparks and may cause a fire.	Smoke, fire.	4C	Tolerable	Aircraft fire systems, procedures for handling personnel and crew, certified luggage racks with the appropriate fire category.
14	Irregular subcontracting on behalf of an air carrier for handling Dangerous Goods	Wrong acceptance, damaged shipments, improper handling.	Lack of compliance, financial penalties, DG transport not in accordance with the regulations, service errors ended with DGOR.	3D	Tolerable	Carrying out inspections and audits, training staff in the handling of hazardous materials.

).

The conducted risk assessment shows that there are many different types of safety hazards resulting from the air transport of lithium-ion batteries. However, after developing a risk assessment using a risk matrix, along with conducting an analysis and assessment of the level of impact of the hazard on operations and the resulting consequences, it is noticeable that they are within an acceptable or tolerable level. This requires the adoption of risk mitigation activities. In the problem under study, the best choice will be to adopt a reduction strategy. This means that it is necessary to monitor the frequency of incidents, conduct educational and awareness-raising activities on the subject of the hazard, and conduct activities to minimize the risk by tightening the current and preventive procedures. The conducted assessment confirms that safety hazards exist, but they are at a level that allows for the continued transport of this type of hazardous materials. The existing hazards do not exclude their presence on board aircraft.

5. Conclusions

The article acknowledges the dynamic development of lithium-ion battery technology and the need to adapt regulations and procedures. The rapid development of battery technologies requires the adaptation of regulations and procedures and regular updating of risk assessments. The article focuses on lithium-ion batteries because they are currently the dominant high-energy-density technology, but extending the perspective to the future generations of energy storage is fully justified. Rather than treating lithium-ion batteries as the only problem, it is worth identifying the key risks that may affect any high-energy-density battery technology.

Maintaining an extensive register of the incidents involving lithium-ion batteries in air transport is an appropriate basis for considering and analyzing air transport safety. Thanks to such a solution used by the FAA, it is possible to identify threats, problems, and errors. Each entity participating in an air operation should maintain such a register, from the air carrier and ground handling agent to airport managers. Each of the above entities should conduct analyses of the potential threats that may occur at the stage of their participation in the operation, thanks to which it is possible to look at the problem comprehensively from different perspectives.

The conducted analysis allowed for the assessment of the risk of the occurrence of the threat, its definition, presentation of the possible effects, and frequency of occurrence. The description of dangerous situations made it possible to indicate the possibility of threats and their harmfulness in handling lithium-ion batteries in air transport. The risk assessment shows the need to monitor or implement corrective actions during a flight in regard to lithium-ion batteries. By having an insight into the identified threats and the frequency of incidents involving lithium-ion batteries in air transport, it is possible to propose a number of solutions aimed at increasing the level of safety.

The fact that a risk assessment has shown that the risks are within acceptable or tolerable levels when risk mitigation measures are in place does not mean that the risk can be ignored entirely. There are several key reasons why caution is still necessary. Each risk assessment is based on a specific sample of data and assumptions. The results may be specific to the analysis method, test conditions, battery type, or carrier. It is possible that in other circumstances (e.g., when a different batch of batteries is being shipped or in an emergency), the risk may increase. The risk is “tolerated” because of the use of safeguards such as special packaging, compatibility testing, or restrictions on the quantities shipped. If these measures are not followed or fail, the risk level may exceed acceptable levels.

Lithium-ion battery technology and the methods of transporting them are constantly evolving. New battery types, changing transport conditions (e.g., increasing the number of batteries being shipped), and new hazards (e.g., higher temperatures in cargo) can all affect the actual level of risk. Some hazards may have a very low probability of occurrence but catastrophic consequences. A lithium-ion battery fire in an aircraft cargo hold is a rare but potentially catastrophic event. High levels of preventive action do not mean that the risk does not exist—it only means that we can control it. Despite the strict regulations, there have been incidents in the past related to the transport of lithium-ion batteries (e.g., fires in the cargo holds of cargo aircraft). History shows that the risk is not just theoretical, but real.

The risk assessment has shown that the hazards are within acceptable or tolerable levels when risk mitigation measures are applied does not mean that the risk can be completely ignored. There are several key reasons why caution should still be exercised. Each risk assessment is based on a specific sample of data and assumptions. The results may be specific to the analysis method, test conditions, battery type, or carrier. It is possible that in other circumstances (e.g., if a different batch of batteries is transported or in an emergency), the risk may increase. The fact that the risk is “tolerable” is due to the use of safeguards such as special packaging, compatibility tests, or restrictions on transported quantities. If these measures are not followed or fail, the risk level may exceed acceptable standards. Identifying risks as “tolerable” does not mean that we can stop worrying. It is the result of preventive measures that must be continually followed and improved. Any deviation from procedures, new battery types, increased transport scale, or unexpected factors can change the level of risk. Therefore, regular updates to safety procedures and further research into ways to minimize the risks are necessary.

The essential aspect of the activities should be education and raising the awareness of the occurrence of the threat. It is necessary to conduct cyclical training on handling hazardous materials for all employees participating in the process of the flight operation. This training must be comprehensive, compliant with IATA requirements, and confirmed by a final exam passed by over 80%. The training should show threats, such as fires or gas releases, and indicate the methods of an effective response to dangerous situations. The presented results may help improve safety procedures and educate flight personnel and passengers. Due to the very dynamic development of lithium-ion power supply technology for many devices available on the market, it is important to continue the research into the safety of their transport and to adapt regulations and procedures to the changing needs and challenges.

In addition to specialized staff training, it is necessary to make passengers aware of the potential threat. A common problem is the lack of passenger knowledge that they have a device powered by a lithium-ion battery, which can lead to a threat through improper use of the battery. Passengers are often unaware of the risks associated with the carriage of devices powered by lithium-ion batteries. Therefore, it is important to implement educational programs that make passengers aware of the risks associated with the improper carriage and use of devices with batteries. Conducting a campaign to make passengers aware of the maximum limits of batteries carried in luggage and how to secure them properly during travel can be beneficial and minimize dangerous situations.

The lack of awareness and improper handling of lithium-ion batteries by passengers and ground crew are significant risk factors in air transport. Education and appropriate training can significantly improve the safety in this area. Ground crew play a key role in ensuring the safety of air operations, including handling hazardous materials such as lithium-ion batteries. The training for this group of employees should include the ability to recognize different types of batteries and understand the risks associated with them. Regular and mandatory training can significantly reduce the number of incidents related to the improper handling of batteries.

In summary, investment in training for ground crew and awareness programs for passengers is crucial to minimize the risks associated with transporting lithium-ion batteries by air. Further research on the behavioral aspects and evaluation of the effectiveness of these programs can provide valuable insights into their optimization and the implementation of best practices in the aviation industry.

Another important aspect that requires constant development and expansion of the scope of action is the physical method of transporting hazardous materials, through the use of fireproof containers for loading luggage and transported goods. The implementation of fireproof containers, thermal bags, and training programs is associated with specific costs, but their effectiveness in increasing the safety of transporting lithium-ion batteries is invaluable. Fireproof containers are an important element in minimizing the risk of fire during the transport of lithium-ion batteries. The use of such containers can effectively limit the spread of fire in the event of a battery ignition. The implementation costs depend on the materials used to manufacture the containers and their technical specifications. High-quality containers can be a significant investment, but their effectiveness in preventing aircraft disasters makes them a cost-effective solution. The decision to select appropriate measures should consider the specifics of the carrier’s operations, cost analysis, and the potential risk associated with transporting this type of material. This aspect should be further analyzed in this area.

In terms of the appropriate protection of the passenger cabin, it must be equipped with fire extinguishing agents that can be used in the event of a fire caused by lithium-ion batteries, such as liquefied carbon dioxide (CO2) extinguishers or special chemical substances. In order to respond appropriately to the threat at the initial stage of its occurrence, i.e., in the event of overheating of the device accompanying the passenger, the crew should be provided with access to the so-called thermal containment bag, i.e., special bags that allow for minimizing the negative development of the dangerous situation. After detecting an overheated device, it should be safely placed in an insulating bag, which will prevent further escalation of overheating without causing a fire. This solution gives time to respond appropriately and decide whether to continue or interrupt the flight operation. Due to the high frequency of incidents related to items carried in the passenger cabin as hand luggage, this solution should be used by all air carriers due to its comprehensive application to various types of devices powered by lithium-ion batteries. Properly designed thermal bags can maintain a stable battery temperature, even in extreme conditions. The purchase and implementation costs of such bags are usually lower than fireproof containers, making them an attractive option for carriers. However, the effectiveness of thermal bags depends on their design and the quality of the materials used.

The development and application of a comprehensive approach to the issue of the safe transport of lithium-ion batteries by air includes a number of necessary actions necessary to achieve a satisfactory effect of increasing safety. Proposed solutions include the use of special fireproof containers or thermal bags, training of airport and cabin crew, equipping aircraft and places that have direct contact with hazardous materials with fire extinguishing agents, monitoring the production method of new devices entering the technological market, setting appropriate limits on the number of batteries on board, research on new technologies, and strict regulations and provisions. Training personnel in the field of identification, handling incidents, and communicating with passengers are key elements of ensuring safety. Together, these actions can increase air travel safety and minimize the risk associated with the transport of lithium-ion batteries.

Recommendations are proposed to improve the safety of battery transport, namely introducing mandatory training for personnel in the identification and handling of endangered batteries, implementing modern procedures for monitoring battery temperature in cargo, e.g., by using thermal sensors in real time, and increasing the use of fireproof containers for large-scale battery transport.

Recommendations and improvements should be related to legislative actions, namely introducing the standardization of the global requirements for the certification of batteries transported by air, including mandatory tests for used and reconditioned batteries, introducing stricter standards for the packaging and transport of high-capacity batteries to reduce the risk of fire, and expanding incident reporting to include detailed information on transport conditions (e.g., humidity, temperature, battery charge level).

Recommendations to improve safety should also be addressed to the manufacturers of batteries and electronic devices in order to design batteries with built-in systems for the independent detection of overheating and damage, introducing intelligent chips that track cell status in real time, and introducing mandatory certification and tests of fireproof packaging for batteries transported in large quantities.

Due to the rapid development of battery technologies, future research should focus on several key areas related to advanced battery packaging technology related to the development of self-extinguishing packaging materials capable of absorbing heat when overheated, the introduction of active cooling systems in cargo units carrying large quantities of lithium-ion batteries, and the development of nanotechnology-based fire-resistant structures that can limit the spread of fire in the event of a failure. Future research work should concern the development of risk detection models based on artificial intelligence, the application of artificial intelligence (AI) to predict battery failures based on large sets of historical data, and the introduction of predictive battery failure detection systems that could warn of potential incidents.