Safety Recommendation A-12-070

-From Bryan Bedford, Administrator: The Federal Aviation Administration (FAA) met with the National Transportation Safety Board (NTSB) on April 17, 2025, to discuss a path towards meeting the safety intent of these two safety recommendations. We do not plan to implement these recommendations through rulemaking but will continue supporting industry efforts to develop related aircraft fire safety-enhancing options. It was agreed to keep recommendations A-12-68 and A-12-70 open to allow the FAA to:

• Investigate technologies that would provide information to the aircraft from cargo container heat sensors;

• Allow the Commercial Aviation Safety Team (CAST) to complete its actions related to safety enhancements (SEs) 224, Cargo - Hazardous Material Fires – Enhanced Fire Detection Systems (R-D), and 225, Cargo – Hazardous Material Fires – Containment and Suppression (R-D); and

• Support the development of industry standard Underwriters Laboratories (UL) 5810 “Test Method for Evaluating Fire Protection Systems for Air Cargo Containers,” which will provide standards for active fire suppression in cargo containers.

Additional information on these CAST safety enhancements are available at the following websites: https://skybrary.aero/articles/se224-cargo-hazardous-material-fires-enhanced-fire-detection-systems-r-d https://skybrary.aero/articles/se225-cargo-hazardous-material-fires-containment-and-suppression-r-d

We are assessing the above activities and will provide statuses in addressing these two safety recommendations in our next response.

You have told us that you do not have the regulatory authority to require increased flammability standards, fire detection, or active fire suppression systems for cargo containers, which are also referred to as unit load devices (ULDs). On September 23, 2024, my staff contacted your staff for additional details about the FAA’s lack of regulatory authority related to this issue. In a November 8, 2024, email, your staff explained that applicable airworthiness standards apply to a ULD if it is included in the type design for a particular type-certificated aircraft because it would be considered a component part of the aircraft.

However, most aircraft operators do not include ULDs as part of the aircraft’s type design, and, although operators do identify the types of ULDs that may be carried or used in the aircraft flight manual or weight and balance manual, this does not imply that the ULD is “installed” on the aircraft. Your staff informed us that, although the FAA could pursue rulemaking to mandate the actions we requested, the cost/benefit analysis would not support rulemaking because accidents caused by ULDs are so rare. We note that you contacted United Parcel Service and confirmed it no longer uses the crates responsible for these accidents, and the crate manufacturer is no longer in business.

We understand that, notwithstanding its limited ability to regulate cargo containers, the FAA continues to work with industry to develop best practices, technical solutions at the container- and aircraft-levels, and packaging standards that support the safe carriage of goods, including lithium batteries. In addition, you report that operators have shown increased interest in implementing safety enhancements at the cargo container- and aircraft-level.

We also note that Special Airworthiness Information Bulletin 2023-06, “Risk of Uncontrolled Fire Incidents Caused by Aircraft Cargo,” advises aircraft owners and operators who carry cargo of the potential for an uncontrolled fire to occur based on the amount, type, and placement of flammable cargo in the cargo compartment, and recommends mitigations for reducing those risks. Further, Advisory Circular 120-121, “Safety Risk Management Involving Items in Aircraft Cargo Compartments,” contains guidance on assessing the safety risks of items transported in the aircraft cargo compartment.

We continue to believe your ongoing work with industry to develop battery packaging standards and cargo container and cover solutions that can withstand more severe fire loads is positive and responsive to the first part of Safety Recommendation A-12-68. For the second part of Safety Recommendation A-12-68 and for Safety Recommendation A-12-70, we are encouraged to learn that plastic shipping crates are no longer being manufactured and are rarely used, and that operators have expressed an interest in making safety enhancements to their cargo containers.

-From Kathryn B. Thomson, Deputy Administrator: The Federal Aviation Administration (FAA) continues to collaborate with industry members such as the Commercial Aviation Safety Team (CAST), consensus standards organizations such as SAE International, safety forums such as the International Civil Aviation Organization, and other regulatory authorities on best practices, technical solutions at the container- and aircraft-levels, and packaging standards that support the safe carriage of goods. As previously reported, SAE International continues to develop battery packaging standards and cargo container and cover solutions that can contain more severe fire loads, including lithium batteries.

As a result of this collaboration, the FAA issued Special Airworthiness Information Bulletin (SAIB) 2023-06, Risk of Uncontrolled Fire Incidents Caused by Aircraft Cargo, on April 4, 2023. This SAIB advises transport category airplane owners and operators of the potential for uncontrolled in-flight fires during carriage of combustible hazardous material.

The SAIB also recommends that aircraft owners and operators take action to mitigate risk, including the use of Class C cargo compartments, fire containment covers, and fire-resistant containers approved to the latest version of Technical Standard Order (TSO) C90e, Unit Load Devices, published on July 6, 2021, which established requirements for classifying a unit load device (ULD) as a fire-resistant container.

The FAA also previously published Advisory Circular (AC) 120-121, Safety Risk Management Involving Items in Aircraft Cargo Compartments, on September 1, 2021, which provides guidance in performing a safety risk assessment, as part of Safety Risk Management, associated with the transport of various types of items in the aircraft cargo compartment and the value of considering the inherent hazardous properties of these items. The SAIB and AC are located at drs.faa.gov.

In addition, the FAA continues to support research and standards by:

• Enabling the development and certification of technologies and systems that enhance the detection of smoke and fumes;

• Promoting the use of halon replacement agents; and

• Ensuring the safety of future fire extinguishing agents for use in cargo compartment fire suppression systems to mitigate the risk of cargo fires resulting from the carriage of hazardous materials, including lithium batteries.

Mr. Nolen reported that the FAA does not have the regulatory authority to require fire-detection or active fire-suppression systems in cargo containers, but that you plan to encourage operators to use such technology under their individual safety management systems. We note that, on April 4, 2023, you published Special Airworthiness Information Bulletin 2023-06, “Risk of Uncontrolled Fire Incidents Caused by Aircraft Cargo,” which advises owners and operators of Part 25 transport category airplanes of the potential for an uncontrollable fire based on the amount, type, and placement of flammable cargo in the cargo compartment and recommends mitigations for reducing those risks.

We also note that you continue to test fire containment covers (FCCs) and unit load devices (ULDs) with built-in fire detection and suppression systems and are participating in the SAE International Technical Standards Committee, AGE-2 Air Cargo, which is developing battery packaging standards and cargo container and cover solutions.

We believe the FAA’s ongoing efforts to develop standards and test FCCs and ULDs that incorporate fire-detection and fire-suppression systems are responsive to the first part of Safety Recommendation A-12-68. For the second part of Safety Recommendation A-12-68 and for Safety Recommendation A-12-70, we request additional information explaining how the FAA can require that cargo containers meet improved flammability requirements, but not incorporate fire-detection and fire-suppression systems.

Pending our receipt and review of this information, implementation of performance requirements to detect fires originating within cargo containers and pallets, and a requirement to install and use active fire-suppression systems in all aircraft cargo compartments or containers, Safety Recommendations A-12-68 and -70 remain classified OPEN-- ACCEPTABLE RESPONSE.

-From Billy Nolen, Acting Administrator, Federal Aviation Administration: The Federal Aviation Administration (FAA) previously informed the Board that leveraging a safety management system (SMS) allows an operator to employ multiple methods to achieve an intended safety outcome. In accordance with their SMS, operators can choose when to utilize passive fire resistant containers, passive fire containment covers (FCCs), or emerging technologies such as active fire suppression containers as risk mitigations to identified hazards.

The Commercial Aviation Safety Team (CAST), which promotes the voluntary implementation of cargo safety enhancements (SE), also encourages operators to consider implementing cargo risk controls as part of the following CAST’s SEs (available at https://www.cast-safety.org/):

• SE 127: Cargo - Fire Containment

• SE 223: Cargo - Hazardous Materials Fires - Prevention and Mitigation

• SE 224: Cargo - Hazardous Materials Fires - Enhanced Fire Detection Systems (R-D)

• SE 225: Cargo - Hazardous Materials Fires - Containment and Suppression (R-D)

• SE 226: Hazardous Materials Fires - Enhanced Protection of Occupants and Aircraft

The FAA continues to support efforts to expand industry standards to address hazardous cargo. The FAA does not intend to mandate these actions beyond the linkage to SMS, as discussed in Advisory Circular (AC) 120-121, “Safety Risk Management Involving Items in Aircraft Cargo Compartments.” AC 120-121 is located at: drs.faa.gov.

The FAA informed the Board in its September 9, 2020 letter that on April 20, 2020, we published the “Strategies for Improved Fire Detection Response Times in Aircraft Cargo Compartments” research report, DOT/FAA/TC-TT20/15. The FAA continues to support efforts from this report to develop standards and test alternative means to improve the carriage of cargo on aircraft to enhance fire safety. These include testing FCCs and unit load devices (ULD) that incorporate built-in fire detection and suppression systems.

We note that, on April 20, 2020, you published the report, “Strategies for Improved Fire Detection Response Times in Aircraft Cargo Compartments.” This report includes details about the research and testing that you have completed, for a fire located within a cargo container, on the time delay between the fire starting and the cargo compartment smoke detector alarm sounding, evaluating three different leakage rates.

We also note that you continue to support the development of SAE draft standard AS8992, “Fire Resistant Container—Design, Performance and Testing Requirements,” and, once published, you intend to revise Technical Standard Order C90, “Cargo Pallets, Nets and Containers,” to include requirements for fire-resistant containers.

We continue to believe that your planned and completed actions to address this complex safety issue are responsive to these recommendations. Pending implementation of performance requirements to detect fires originating within cargo containers and pallets, and a requirement to install and use active fire-suppression systems in all aircraft cargo compartments or containers, Safety Recommendations A-12-68 and -70 remain classified OPEN-- ACCEPTABLE RESPONSE.

-From Steve Dickson, Administrator: The Federal Aviation Administration (FAA) completed a series of tests conducted at the FAA’s William J. Hughes Technical Center to determine the time delay between fire initialization and the airplane cargo compartment smoke detector alarm annunciation, for a fire located within a cargo container (also known as Unit Load Device- ULD), with three different leakage rates. Below is a description of the research:

• The research focused on tests with a wide variety of fuels: such as heptane, polyurethane, foam (smoldering & flaming), suitcases, shredded paper, wood chips, baled cotton, and lithium-ion batteries, as well as nuisance sources consisting of particulates, such as smoke and baby powder, and increased moisture via a humidifier.

• The research was collected with an array of measurement devices, including: light obscuration meters, carbon monoxide, carbon dioxide, and oxygen gas analyzers, thermocouples, infrared cameras (IR), Scanning Mobility Particle Sizer Spectrometer, blue and IR signal sensors, air sampling smoke detectors, air sampling gas detectors, and traditional smoke detectors. These measurements were used to document the smoke signature and examine the impact of leakage rate for a ULD on the comparative difference in the response of smoke/fire detectors inside and outside of ULDs.

This research utilized a variety of equipment and instruments in order to provide a comprehensive characterization of the environment inside and outside the ULD. On April 20, 2020, the final report was published, titled Strategies for Improved Fire Detection Response Times in Aircraft Cargo Compartments. The broader FAA will review the results and evaluate alternate methods of detecting a fire in these types of cargo containers. This report is available for review at: https://www.fire.tc.faa.gov/reports/listresults.asp?searchList=DOT%2FFAA%2FTCTT20%2F15&listSubmit=

The FAA continues to work with the Commercial Aviation Safety Team as stated in our April 3, 2019, response. Additionally, the FAA continues to provide support in the development of SAE draft standard AS8992, Fire Resistant Container - Design, Performance and Testing Requirements. We anticipate AS8992 will be published by December 2020. Upon publication, the FAA will begin to revise TSO-C90, Cargo Pallets, Nets and Containers, to include fire resistant container requirements. The publication of the TSO-C90 revision is estimated to be completed by the end of 2020. Fire containment covers and fire resistant containers are expected to improve fire safety on aircraft.

We note that the research and testing you previously described in response to these recommendations was delayed because of higher priorities. We also note that, in response to the commercial aviation safety team’s (CAST’s) voluntary safety enhancements, you are developing guidance for air carriers to use to assess and mitigate risks associated with all aspects of hazardous material transportation. In addition, we note that you plan to revise Technical Standard Order C90 to specifically address fire containment assembly testing requirements, fire-resistant containers, and fire-containment covers to improve aircraft fire safety.

We continue to believe that your planned and completed actions are responsive to these recommendations and demonstrate your commitment to addressing this complex safety issue. Pending completion of the CAST’s work, implementation of performance requirements to detect fires originating within cargo containers and pallets, and a requirement to install and use active fire-suppression systems in all aircraft cargo compartments or containers, Safety Recommendations A-12-68 and -70 remain classified OPEN--ACCEPTABLE RESPONSE.

-From Daniel K. Elwell, Acting Administrator: The Federal Aviation Administration (FAA) continues the research and testing described in our previous responses. The FAA's William J. Hughes Technical Center continues testing necessary to determine the time delay between when a fire starts and when the airplane cargo compartment smoke detector alarm goes off (for a fire located within several different types or cargo compartments). In addition, we will evaluate alternative methods of detecting a fire in these types of cargo containers.

Although we anticipated completion of this work by December 2018, this effort was delayed due to the higher priorities associated with airplane Type Certification. We now expect completion by mid-2019.

We continue to work with the Commercial Aviation Safety Team (CAST) to conduct research programs and implement voluntary safety enhancements (SEs) aimed at mitigating the risk of cargo fires. We also support activities recommended in four recently approved SEs developed to mitigate the risk of cargo fires resulting from carriage of hazardous materials, including lithium batteries. • SE-223, Cargo - Hazardous Material Fires - Prevention and Mitigation; • SE-224, Cargo - Hazardous Material Fires - Enhanced Fire Detection Systems; • SE-225, Cargo - Hazardous Material Fires - Containment and Suppression; and

• SE-226, Cargo - Hazardous Material Fires - Enhanced Protection of Occupants and Aircraft.

In response to these CAST SEs, we are working to develop guidance for air carriers to assess and mitigate all aspects of the risk of carrying hazardous materials. This include means to prevent fires involving hazardous materials from occurring on-board aircraft, lessen their impact if they do occur, and provide additional training to enhance flight crew ability to continue safe flight and landing in response to an on-board fire.

We also continue to support the research of operators and manufacturers that would result in the development and certification of technologies and systems that enhance detection of smoke, fire, fumes, and/or other fire effects within Class E cargo compartments and mitigate the effects of a fire involving hazardous materials through improved containment and/or suppression.

The FAA' s Office of Security and Hazardous Materials Safety worked with aviation industry stakeholders to develop and implement improvements to industry best practices, methods, technology, and training to detect and prevent undeclared hazardous materials from entering the shipping systems. These actions completed our work on SE-125, Cargo - Hazardous Materials (Hazmat) Processing. In response to SE-127, Cargo - Fire Management, the FAA continues to support development of SAE draft AS6278, which is now renamed AS8992, Fire Resistant Container - Design, Performance and Testing Requirements.

We note that you continue to test the amount of time it takes for a cargo compartment smoke detector alarm to sound after a fire has initiated within several different types of cargo containers. We also note your ongoing work with the Commercial Aviation Safety Team (CAST) to develop new voluntary safety enhancements (SEs) and research programs aimed at mitigating the risk of cargo fires. You are addressing these SEs by developing standards for improved cargo containers that include fire-suppression or fire-containment systems, and you are working to reduce the risk of cargo fires resulting from hazardous materials, including lithium batteries.

In addition, we are encouraged to learn that, although you are waiting on the results of FAA and industry research before you initiate rulemaking related to fire safety in cargo compartments, some operators and manufacturers are exploring either permanently installing fire protection systems in their cargo compartment or having these features installed in the actual cargo containers.

Your efforts thus far demonstrate your commitment to addressing this important yet complex safety issue. Pending completion of the CAST’s work, subsequent implementation of performance requirements to detect fires originating within cargo containers and pallets, and a requirement to install and use active fire-suppression systems in all aircraft cargo compartments or containers, Safety Recommendations A 12 68 and 70 remain classified OPEN--ACCEPTABLE RESPONSE.

-From Michael P. Huerta, Administrator: The Federal Aviation Administration (FAA) continues the research and testing noted in our July 2016 response. The FAA William J. Hughes Technical Center is in the process of completing testing necessary to determine the time delay between fire initialization and the cargo compartment smoke detector alarm going off, for a fire located within several different types of cargo containers. The testing is the same as described in our earlier responses and was expected to be completed by December 2016.

However, testing was delayed due to higher priority research related to determining the flammability and hazards associated with the carriage of lithium batteries. Based on a reprioritized test plan, we now expect this testing to be completed in 2018.

In addition, the FAA has worked with the Commercial Aviation Safety Team (CAST) to develop new voluntary safety enhancements (SEs) and research programs aimed at mitigating the risk of cargo fires. CAST SE 127, "Cargo - Fi re Management," recommends development of standards for the construction of standardized and improved cargo containers that include fire-suppression or fire-containment systems. In response to CAST SE 127, the FAA supported development of SAE Aerospace Standard 6453, '"Fire Containment Cover - Design, Performance, and Testing Requirements," and incorporated the SAE standards in Technical Standard Order (TSO) TSO-C203, "Fire Containment Covers.''

Also in response to CAST SE 127, the FAA continues to provide similar support in the development of SAE draft standard AS6278, "Fire Resistant Container- Design, Performance and Testing Requirements." Fire containment covers and fire resistant containers are expected to improve fire safety on aircraft.

Furthermore, the FAA participated on the recent working group related to CAST SE 126,·cargo - Mitigations for Hazardous Material Fires.'· The working group included government and industry experts in cargo operations and hazardous materials. This working group concluded its activities and developed four new SEs that were approved by CAST in December 2016.

These new SEs are specifically targeted at reducing the risk of cargo fires resulting from carriage of hazardous materials, including lithium batteries. In response to these SEs, the FAA plans to develop guidance for air carriers to assess and mitigate the risk of carrying hazardous materials.

We note your continuing support for the efforts of the Commercial Aviation Safety Team (CAST), whose Safety Enhancements 125, 126, and 127 are being developed to improve aircraft fire-detection and containment systems. We also note that the CAST made multiple presentations on this topic at the FAA’s 2015 International Aircraft Systems Fire Protection Working Group.

Pending completion of the CAST’s work, subsequent implementation of performance requirements to detect fires originating within cargo containers and pallets, and a requirement to install and use active fire-suppression systems in all aircraft cargo compartments or containers, Safety Recommendations A 12 068 and 070 remain classified OPEN—ACCEPTABLE RESPONSE.

-From Michael P. Huerta, Administrator: The Federal Aviation Administration (FAA) continues the research and testing noted in our October 2014 response. We continue to expect testing to be completed by December 2016.

The FAA continues to work through the Commercial Aviation Safety Team (CAST) to address improvements for cargo fire protection, including the aircraft's capability to detect and control fires that could be exacerbated by the presence of hazardous cargo. CAST Safety Enhancements 125, 126, and 127 are expected to improve cargo fire containment systems for air cargo operations.

In addition, the FAA's International Aircraft Systems Fire Protection Working Group convened on October 21-22,2015. During this meeting, CAST provided multiple presentations related to the analysis and improvement of aircraft fire protection systems. These presentations are available at the following Web site: https://www.fire.tc.faa.gov/systems.asp#pres. I will keep the Board informed of the FAA's progress on these safety recommendations and provide an update by April 30, 2017.

We note your continuing support for the efforts of the Commercial Aviation Safety Team’s Safety Enhancements 125, 126, and 127, which are developing improved fire containment systems, and the other activities described in your letter to develop and evaluate new fire extinguishing agents and delivery systems. Pending completion of those efforts and the subsequent implementation of appropriate requirements, Safety Recommendations A 12 68 and 70 remain classified OPEN—ACCEPTABLE RESPONSE.

-From Michael P. Huerta, Administrator: The Federal Aviation Administration continues to support the Commercial Aviation Safety Team Safety Enhancements 125, 126, and 127 to develop improved fire containment systems. We are evaluating the use of new methods for the carriage of cargo and to develop new fire extinguishing agents and delivery systems. We are currently testing means to detect fires in cargo containers and cargo pallet and net assemblies.

In addition, we have completed several fire tests with an enhanced cargo container and are in the process of approving an enhanced cargo container that incorporates fire protection features that can detect and suppress a fire originating within the container. As we complete testing, we are assessing if a higher level standard would provide a safety benefit proportionate to the likely cost. We expect to complete testing by December 31, 2016.

I will keep the Board informed of our progress on this recommendation and provide an update by July 31, 2015.

We believe the FAA’s efforts, with industry and other government agencies, to evaluate the use of new fire extinguishing agents, delivery systems, and advanced cargo containers that would detect and suppress a fire originating within the container are responsive to these recommendations. Pending our receipt and review of the FAA’s findings and completion of the recommended actions, Safety Recommendations A-12-68 and -70 are classified OPEN—ACCEPTABLE RESPONSE.

Notation 8477 (Dated 3/8/2013): The National Transportation Safety Board (NTSB) has reviewed the Pipeline and Hazardous Materials Safety Administration’s (PHMSA) notice of proposed rulemaking (NPRM), “Hazardous Materials: Transportation of Lithium Batteries.” The notice requested additional comments about the impact of changes to the requirements for the air transport of lithium batteries that have been adopted into the 2013–2014 International Civil Aviation Organization Technical Instructions on the Transport of Dangerous Goods by Air (ICAO Technical Instructions) and subsequently incorporated by reference in the Hazardous Materials Regulations (HMR).

The NTSB notes that PHMSA is considering the long-term impacts of permitting shippers and carriers to choose between compliance with the existing HMR or compliance with the ICAO Technical Instructions, when transporting lithium batteries domestically by air. The NTSB further notes that PHMSA is seeking comment on whether to require mandatory compliance with the ICAO Technical Instructions for all shipments of lithium batteries by air, both foreign and domestic.

The NTSB believes that allowing domestic cargo shippers and carriers to choose between alternative standards for transporting lithium batteries would place carriers at greater risk when transporting such cargo in accordance with US regulations that currently provide less protection than the ICAO Technical Instructions. On April 14, 2010, the NTSB provided comments on the January 11, 2010, NPRM.

The 2010 NPRM proposed new requirements to address NTSB Safety Recommendations A-07-104, A-07-105, and A-07-107 through -109 that were issued as a result of the NTSB investigation of the February 7, 2006, in-flight cargo fire on a United Parcel Service Company (UPS) cargo airplane at Philadelphia International Airport in Philadelphia, Pennsylvania. The 2010 NPRM acknowledged that under the HMR, materials that pose a specific and serious air transportation risk are regulated more stringently than materials that pose less of a risk when transported by air, with lithium batteries being the current exception to this standard.

Included in the proposals at that time was the elimination of regulatory exemptions for packages of small lithium batteries. The NTSB stated that cargo shipments of small lithium batteries should be subject to the same packaging and identification requirements that apply to medium and large lithium batteries to increase the awareness of the risks associated with these batteries and to alert package handlers to exercise greater care when loading and unloading packages containing them.

-From Michael P. Huerta, Administrator: The Federal Aviation Administration (FAA) continues to support efforts to improve fire protection in transport airplane cargo compartments. Fire protection in aircraft cargo operations involves numerous considerations. We agree that improvements can be made in several elements of aircraft cargo fire protection systems, including improvements in installed aircraft systems and equipment and cargo containers. The FAA is working through the Commercial Aviation Safety Team (CAST) to address improvements for cargo fire protection, including the aircraft's capability to detect and control fires that could be exacerbated by the presence of hazardous cargo.

These CAST initiatives are expected to develop improved cargo fire containment systems to achieve safety improvements for air cargo operations.

To address Recommendations A-12-68 and -70, the FAA is working with industry and other Government agencies to evaluate the use of new fire extinguishing agents and delivery systems as well as advanced cargo containers that incorporate fire protection features that may detect and suppress a fire originating within the container. The FAA is evaluating whether a new higher-level standard would provide a safety benefit commensurate to the likely cost. Regarding Recommendation A-12-69, the FAA agrees that cargo container materials should not exacerbate a fire.

However, we are not aware of any service evidence that demonstrates FAA regulations for approved cargo containers are inadequate for ordinary combustibles. We will evaluate the results of the Board's cargo containment fire study to determine what, if any, further action may be needed to address this recommendation.

I will keep the Board informed of the FAA's progress on these safety recommendations and provide an update by December 2013.