The application process for most TSA career positions is conducted through USAJobs.gov, the official government hiring site. Most job postings include an option or requirement to apply online. The How to Apply page on the TSA website links to USAJobs.gov.
Many career positions with the TSA have different application requirements, outlined on the specific job postings on USAJobs.gov. Additionally, all TSA jobs require a full background investigation, and security officer positions require a medical examination, physical ability test, drug and alcohol screening, aptitude test and English proficiency.
On its website, TSA provides a link to the initial application form for is federal flight deck officer positions, known as the volunteer questionnaire form.