The following operations will continue as excepted activities during a lapse in annual appropriations and lapse in authorization:
• Air traffic control services
• Maintenance and operation of navigational aids and other facilities, including support to reimbursable Department of Defense
and Department of Homeland Security activities;
• Flight Standards field inspections;
• Airworthiness Directives
• Airmen medical certifications;
• Certain certification activities;
• Issuance of waivers for UAS and in support of other safety and security operations;
• Approval of exemptions for unmanned aerial systems operations;
• Hazardous materials safety inspections (safety inspectors will be recalled as necessary over time to maintain the safety of the
system and/or respond to incidents);
• Air Traffic Control Specialist (ATCS) medical clearances;
• Air traffic safety oversight (limited);
• On-call accident investigations;
• Commercial space launch oversight, and licensing;
• Command, control, communications, and intelligence (i.e., Regions and HQ Operations Centers, Intelligence Threat Watch,
and emergency communication support);
• Foreign relations on aviation safety-related matters;
• FAA's aircraft and airman registry;
• Congressional liaison services, to the extent that they are necessarily implied from the authorized continuation of legislative
activity;
• Support functions necessary to provide timely payments to contractors and grantees.

https://www.transportation.gov/sites...09-22-2023.pdf

My comment:

This is not to say that employees will not succumb to allergies and other sick, flu like symptoms, consistent with fall weather and seasonal patterns. The shutdown does not shut down the human body's chances of getting sick.