Certain COVID-19 Vaccines Require A Temperature Of -70°C (-94°F) For Proper Preservation

Noting that dry ice is widely used in aviation to keep perishable goods cold as they traverse the supply chain, the FAA has published a SAFO (Safety Alert for Operators) to urge caution in flying larger amount of freight using this cooling system.

When properly vented and shipped in small quantities, dry ice poses little risk to aircraft occupants. However, when a large amount of dry ice is involved, sublimation can cause serious risks. The sublimation of dry ice occurs when it passes directly from a solid state to a gaseous state at temperatures higher than -78° C (-108.4°F), under normal atmospheric pressure.

Certain COVID-19 vaccines require a temperature of -70°C (-94°F) for proper preservation. The primary means of  maintaining this temperature involves packing the vaccine container with dry ice. In order to transport COVID-19 vaccines, operators may plan to carry dry ice quantities larger than quantities they may carry during typical operations.

"This volume of dry ice may present risks that existing mitigations do not adequately address."

A potential risk associated with the sublimation of dry ice is that gaseous CO2 will replace oxygen in aircraft compartments and interfere with the breathing abilities of the occupants. High levels of CO2 gas in compartments can lead to unrecognized degradation of cognitive functioning and present an asphyxiation hazard to persons in that space (e.g., ground crew who handle the loading and unloading of cargo containers). The risk of hazardous conditions increases proportionately with the amount of the dry ice carried, the sublimation rate of that dry ice, and any ventilation degradation of the aircraft.

The SAFO provides information and recommendations to persons conducting operations under Title 14 of the Code of Federal Regulation (14 CFR) Parts 121, 125, 129, 135 on safety issues related to the transportation of COVID-19 vaccines by air, which may require larger than typical quantities of dry  ice for preservation. Operators must comply with applicable federal regulations pertaining to the carriage of dangerous goods (49 CFR parts 171-180).

FMI: www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2020/SAFO20017.pdf