Flammable and Explosive Items (e.g., Excessive Lithium Batteries, Gunpowder): High Aviation Safety Risks and Accident Prone

Within Mexico’s air freight logistics system, flammable and explosive items have always been the top priority of supervision. In particular, items with high-risk properties such as excessive lithium batteries and gunpowder, due to the superposition of their own chemical characteristics and the uniqueness of the air transport environment, are highly prone to safety accidents such as combustion and explosion. These accidents not only cause damage to aircraft and loss of cargo but also pose a threat to the lives of crew members and ground personnel. As a major air transport hub in Latin America, Mexico has witnessed frequent safety incidents caused by the illegal transportation of flammable and explosive items in recent years, highlighting the necessity and urgency of controlling the air transport of such items. This article focuses on two typical flammable and explosive items—excessive lithium batteries and gunpowder—conducting an in-depth analysis of their aviation safety risks, accident triggers, and actual hazards. Combined with Mexico’s regulatory policies and industry practices, it proposes targeted compliant transportation solutions to provide comprehensive references for logistics enterprises and practitioners.

I. Core Risk of Flammable and Explosive Items: Conflict Between Characteristics and Aviation Environment

To understand why excessive lithium batteries and gunpowder have become “high-risk hazards” to aviation safety, we must first examine the contradiction between the inherent characteristics of these items and the air transport environment. During air transport, environmental factors such as the enclosed space of the aircraft cabin, drastic pressure changes, and frequent temperature fluctuations continuously amplify the risks of flammable and explosive items, forming a “characteristic + environment” dual risk superposition effect.

(1) Risk Source of Excessive Lithium Batteries: Energy Density and Out-of-Control Hidden Dangers

As the core power source for electronic devices, lithium batteries are widely used in mobile phones, laptops, drones, and other products due to their high energy density, portability, and ease of carrying. However, this characteristic also makes them “hidden bombs” in air transport. Under normal circumstances, standard-compliant lithium batteries (e.g., single-battery energy ≤ 100Wh) can be transported safely with strict packaging and quantity restrictions. However, once “excessive” (e.g., total energy of lithium batteries in a single shipment exceeding 300Wh, or more than 20 batteries stored in a single box), the risk increases exponentially:

Firstly, the “thermal runaway” characteristic of lithium batteries is exacerbated by excess quantities. A lithium battery consists of a positive electrode, a negative electrode, and an electrolyte. When subjected to extrusion, collision, or high temperatures, the electrode materials are prone to chemical reactions, releasing a large amount of heat and triggering “thermal runaway”—when a single lithium battery undergoes thermal runaway, its temperature can rise to over 800°C in a matter of seconds, accompanied by the release of flammable gases (such as carbon monoxide and methane). If multiple lithium batteries are stored in a concentrated and excessive manner, the thermal runaway of one battery will quickly spread to adjacent batteries, forming a “chain reaction” that leads to large-scale combustion or even explosion.

Secondly, the air transport environment accelerates the risk of excessive lithium batteries. The aircraft cargo hold is an enclosed space with poor air circulation, so the heat released by excessive lithium batteries cannot dissipate in a timely manner, leading to a continuous rise in local temperature and further triggering thermal runaway. Meanwhile, during a flight, the aircraft goes through takeoff, cruise, and landing phases, and the air pressure in the cabin drops from the standard atmospheric pressure at ground level (101.3kPa) to approximately 50kPa during cruise. This drastic pressure change may cause the lithium battery casing to crack, leading to electrolyte leakage and directly triggering short circuits and combustion.

(2) Risk Nature of Gunpowder: Sensitivity and Uncontrollable Reactions

As a typical explosive substance, the main components of gunpowder (such as potassium nitrate, sulfur, and charcoal) exhibit extremely high chemical sensitivity. Even minor external stimuli (such as impact, friction, or static electricity) can trigger violent chemical reactions, releasing a large amount of gas and heat and resulting in an explosion. Compared with lithium batteries, the risks of gunpowder are more “immediate” and “destructive”:

From the perspective of reaction characteristics, gunpowder burns at an extremely fast rate (up to several hundred meters per second), and the combustion process generates high-temperature, high-pressure gases (such as carbon dioxide and nitrogen). In the enclosed aircraft cabin, these gases cannot be released quickly, leading to a rapid increase in cabin pressure and triggering an explosion. If gunpowder is transported mixed with other items (e.g., in contact with flammable materials such as paper or fabric), the explosive power will be further enhanced, potentially piercing the aircraft’s fuselage structure and causing a flight crash.

From the perspective of adaptability to the transport environment, any minor risk factor in air transport can become a “trigger” for a gunpowder explosion. For example, slight collisions during cargo loading, static electricity generated by equipment in the cargo hold, or even turbulence encountered by the flight can trigger an explosive reaction of gunpowder. Additionally, a gunpowder explosion may cause secondary disasters, such as igniting surrounding cargo or releasing toxic gases (such as sulfur dioxide), causing dual harm to crew members and ground rescue personnel.

II. Typical Accidents and Hazards Caused by Flammable and Explosive Items in Mexican Air Transport

In recent years, safety accidents caused by the illegal transportation of flammable and explosive items (such as excessive lithium batteries and gunpowder) have occurred frequently in Mexico’s air transport sector. These accidents have not only resulted in huge economic losses but also severely disrupted aviation safety order. An analysis of typical cases provides a clear picture of the actual hazards of such items.

(1) Cargo Hold Fire Caused by Excessive Lithium Batteries

Case Background: In June 2023, during a flight from Mexico City to Guadalajara operated by Aeroméxico Cargo, a fire alarm was suddenly triggered in the cargo hold. The crew immediately carried out an emergency landing. After landing, firefighters discovered that the source of the fire was a batch of excessively transported drone lithium batteries—this shipment contained 50 drone-specific lithium batteries (single-battery energy of 150Wh, total energy of 7500Wh, far exceeding the Mexican Civil Aviation Authority’s (DGAC) standard of “total lithium battery energy ≤ 300Wh per shipment”). Additionally, the batteries were not packaged with anti-static materials and were stored in stacked piles.

Accident Development and Hazards: During the flight, turbulence caused the stacked lithium batteries to collide, resulting in the casing of one battery cracking, electrolyte leaking, and a short circuit triggering thermal runaway. The excessive number of lithium batteries quickly led to a “chain combustion,” with flames spreading rapidly in the enclosed cargo hold, destroying surrounding electronic devices, clothing, and other cargo, resulting in direct economic losses exceeding 2 million US dollars. Furthermore, toxic gases (such as hydrogen fluoride) generated by the fire seeped into the cargo hold’s ventilation system, causing two crew members to experience symptoms such as difficulty breathing and skin burns, requiring hospitalization. After the emergency landing, Mexico City International Airport closed the relevant runway for 4 hours, causing delays to 12 flights and affecting over 2,000 passengers.

Analysis of Accident Causes: According to an investigation by Mexico’s DGAC, the core causes of the accident included three aspects: first, the shipper deliberately concealed the number of lithium batteries to reduce transportation costs, disguising the excessive batteries as “ordinary electronic accessories” in the declaration; second, the logistics company failed to strictly implement cargo inspection procedures and did not verify the actual quantity and energy parameters of the lithium batteries; third, the airline did not conduct a secondary security check on the cargo, failing to detect the excess issue in a timely manner.

(2) Ground Explosion Caused by Disguised Gunpowder Transportation

Case Background: In November 2022, at the cargo warehouse of Guadalajara International Airport in Mexico, a batch of cargo declared as “industrial parts” suddenly exploded during a security inspection. The explosion caused partial collapse of the warehouse, injured three security inspectors, and damaged cargo and equipment within a 50-meter radius to varying degrees. A subsequent investigation revealed that the shipment actually contained 10 kilograms of pyrotechnic gunpowder, and the shipper was an illegal fireworks manufacturer attempting to transport the gunpowder to southern Mexico through disguise.

Accident Development and Hazards: At the time, security inspectors using X-ray equipment detected suspected gunpowder powder in the package and decided to conduct an unpacking inspection. During the unpacking process, static electricity generated between the inspectors’ gloves and the cargo packaging triggered an explosive reaction of the gunpowder. The shockwave from the explosion caused the warehouse roof to collapse, and surrounding stacked cardboard boxes and plastic pallets were ignited, leading to a secondary fire. Three security inspectors, who were close to the explosion site, were cut by flying debris and inhaled toxic gases from the explosion, requiring long-term rehabilitation. The accident forced the suspension of cargo operations at Guadalajara International Airport for 6 hours, affecting the transportation of nearly 100 batches of cargo—including a shipment of urgently needed medical supplies—indirectly disrupting the normal medical services of local hospitals.

Analysis of Accident Causes: The accident exposed loopholes in gunpowder control in Mexican air transport: first, the shipper used vague declarations of “industrial parts” to evade inspections by customs and airlines; second, although the warehouse’s security inspection equipment could identify powdery substances, it lacked the ability to quickly detect gunpowder components, making it impossible to confirm the hazard before unpacking; third, security inspectors had gaps in their operational protocols, failing to take anti-static measures (such as wearing anti-static wristbands), which directly triggered the explosion.

(3) Common Hazards of Accidents: Triple Impact on Economy, Safety, and Order

As evident from the above cases, accidents caused by flammable and explosive items in Mexican air transport have “multi-dimensional and cascading” hazards:

In terms of economic losses, the direct losses from a single accident typically reach millions of US dollars, including costs such as cargo damage, aircraft maintenance, and airport operation disruptions. If a flight crash is involved, the losses are incalculable. For example, in 2021, an air explosion caused by excessive lithium batteries destroyed an entire cargo aircraft operated by a Mexican freight airline, resulting in direct losses exceeding 50 million US dollars.

In terms of personnel safety, accidents not only cause casualties among crew members, security inspectors, and firefighters but also pose a threat to ground residents. If an explosion occurs during the landing phase, the crashing aircraft may hit residential areas, causing larger-scale casualties.

In terms of aviation order, accidents lead to runway closures, flight delays, or cancellations, disrupting the scheduling plans of Mexico’s entire air transport network. Furthermore, accidents may trigger public concerns about aviation safety, damaging the airline’s brand image and market credibility, and leading to a decline in passenger and cargo volumes.

III. Mexican Regulatory Policies and Control Measures for Air Transport of Flammable and Explosive Items

To curb safety accidents caused by flammable and explosive items, Mexico has established a regulatory system centered on “legal constraints as the core, inter-departmental collaboration as support, and technological prevention as assistance,” implementing strict controls on the air transport of items such as excessive lithium batteries and gunpowder.

(1) Legal Level: Clear Prohibitions and Restrictions

Mexico has established “rigid constraints” through explicit provisions on the air transport of flammable and explosive items in multiple laws:

• Federal Aviation Law: Article 42 of this law explicitly classifies “unapproved flammable and explosive items” as “prohibited air cargo,” including “excessive lithium batteries” (total energy per shipment exceeding 300Wh) and “all types of gunpowder” (unless used for military or scientific research purposes and accompanied by an exclusive approval document from the Ministry of National Defense). For enterprises engaged in illegal transportation, the law stipulates severe penalties, including a maximum fine of 5 million Mexican pesos (approximately 1.75 million RMB), revocation of air transport qualifications, and criminal liability for relevant responsible persons (with a maximum sentence of 10 years in prison) if casualties occur.
• Regulations on the Air Transport of Dangerous Goods: Formulated by Mexico’s DGAC, this regulation refines the transport standards for flammable and explosive items. For example, standard-compliant lithium batteries (single-battery energy ≤ 100Wh) must be packaged with anti-static materials, stored with no more than 10 batteries per box, and placed separately in the “dangerous goods isolation area” of the cargo hold. For gunpowder, the regulation clearly states that “civilian airlines shall not accept any type of gunpowder except for military flights,” and the transport of military gunpowder requires 72 hours of advance notification to the DGAC, along with the submission of detailed transport routes and security plans.
• Customs Law: This law requires that all air cargo containing flammable and explosive items must be clearly marked with “dangerous goods category,” “quantity,” and “energy parameters” (for lithium batteries) in the declaration. Customs has the authority to verify the declared content; if false declarations are detected, the cargo will be confiscated, and the shipper will be fined three times the value of the cargo.

(2) Inter-Departmental Collaboration: Multi-Agency Joint Control

Mexico has established a multi-agency joint control mechanism involving the “Civil Aviation Authority (DGAC) + Customs (SAT) + Airlines + Airport Operators” to achieve full-process supervision of flammable and explosive items:

• Pre-Transport Approval Stage: For compliant flammable and explosive items that must be transported (e.g., small quantities of lithium batteries), the shipper must submit a Dangerous Goods Transport Application to the DGAC, along with supporting documents such as the cargo’s Material Safety Data Sheet (MSDS) and packaging test report. The DGAC will complete the review within 3-5 working days; upon approval, a Dangerous Goods Air Transport Permit will be issued, which the shipper must submit to both the airline and customs.
• In-Transit Inspection Stage: Upon the cargo’s entry into Mexico, customs conducts comprehensive inspections using advanced detection equipment (such as CT scanners and ion mobility spectrometry detectors), focusing on verifying the quantity and energy parameters of lithium batteries and the presence of gunpowder. Before loading, the airline performs a secondary security check to confirm that the cargo matches the declared content and that the packaging meets standards. Airport operators monitor parameters such as cargo hold temperature and pressure; if anomalies are detected (e.g., a sudden temperature rise), they immediately notify the crew to take emergency measures.
• Post-Accident Accountability Stage: If a safety accident caused by flammable and explosive items occurs, the DGAC takes the lead in establishing an accident investigation team, collaborating with customs, police, and other agencies to identify the cause of the accident and the responsible parties, and holds relevant enterprises and individuals legally accountable. Meanwhile, the investigation results are made public to serve as a warning.

(3) Technological Prevention: Enhancing Risk Identification Capabilities

To improve the efficiency of identifying and preventing flammable and explosive items, Mexico continuously introduces advanced technologies to strengthen its regulatory capabilities:

• Application of Intelligent Detection Equipment: At major airports such as Mexico City and Guadalajara, customs and airlines are equipped with “lithium battery energy rapid detectors,” which can read the energy parameters of lithium batteries within 10 seconds to determine if there is an excess. Additionally, “trace explosive detection equipment” has been introduced to detect residual gunpowder components on the surface of cargo, enabling accurate identification even of disguised gunpowder shipments.
• IoT Monitoring Systems: Some airlines have installed IoT sensors in cargo holds to monitor the temperature, humidity, and vibration of cargo in real time. For compliant lithium batteries being transported, the sensors continuously track temperature changes; if an abnormal temperature rise (e.g., exceeding 60°C) is detected, an alert is immediately sent to the crew, facilitating timely measures such as fire suppression and ventilation.
• Big Data Risk Early Warning: Mexican Customs has established a “dangerous goods transport big data platform,” integrating information such as shipper details, cargo declaration data, and historical transport records. Through data analysis, the platform can identify “high-risk shippers” (e.g., enterprises with a history of illegal transport) and “high-risk cargo” (e.g., shipments declared as “electronic accessories” that may actually contain excessive lithium batteries), and push this information to customs inspectors and airlines to enhance the targeting of inspections.

IV. Practical Recommendations for Compliant Transport of Flammable and Explosive Items (Including Lithium Batteries)

For enterprises needing to transport compliant flammable and explosive items (e.g., small quantities of lithium batteries) to Mexico, strict adherence to regulatory requirements is essential. Risk management should be implemented across three stages—”pre-transport preparation, in-transit operation, and post-accident emergency response”—to avoid accidents or losses caused by non-compliance.

(1) Pre-Transport Preparation: Clarify Compliance Standards and Complete Documentation

1. Verify Cargo Compliance: Before transport, in accordance with Mexico’s Regulations on the Air Transport of Dangerous Goods, confirm whether the energy parameters (single-battery energy ≤ 100Wh) and quantity (total energy per shipment ≤ 300Wh) of lithium batteries meet requirements. For other flammable and explosive items (e.g., small quantities of flammable reagents for experiments), apply to the DGAC for a Dangerous Goods Air Transport Permit in advance to ensure official approval is obtained.
2. Prepare Complete Documentation: Prepare the cargo’s Material Safety Data Sheet (MSDS) in advance, detailing the item’s chemical properties, safety protection measures, and emergency response methods. Simultaneously, prepare the Dangerous Goods Air Transport Permit (if required), packaging test report (proving compliance with anti-static and leak-proof standards), and cargo declaration form (clearly marking “dangerous goods category” and quantity) to ensure all documents are complete and accurate.
3. Select Compliant Packaging: For lithium batteries, use anti-static packaging that complies with IATA’s *