AF Form 4170: EMSEC Assessments & Countermeasures Review – U.S. Air Force personnel working with classified information systems, communications equipment, or cryptographic devices must understand Emission Security (EMSEC). AF Form 4170, titled Emission Security Assessments / Emission Security Countermeasures Review, serves as the primary document for identifying potential vulnerabilities from compromising emanations and documenting required protective measures.
This form supports the Air Force’s Information Assurance (IA) and communications security programs by ensuring sensitive data remains protected from unauthorized interception through electromagnetic signals.
What Is Emission Security (EMSEC)?
Emission Security (EMSEC), often associated with the older term TEMPEST, protects against the unintentional release of compromising emanations—radiated or conducted electromagnetic signals from equipment processing classified or sensitive information. These emanations could allow adversaries to reconstruct data from a distance.
EMSEC includes:
- Assessments — Evaluating equipment and facilities to determine the “inspectable space” (the area where emanations could be exploited).
- Countermeasures Reviews — Identifying specific protections needed for information systems, communications systems, and cryptographic equipment.
The goal is to contain compromising emanations within a controlled “inspectable space” using zoning, shielding, equipment selection, or other methods. EMSEC forms a key part of broader COMSEC (Communications Security) and IA programs under Air Force Policy Directive (AFPD) 33-2 and related instructions.
Note: EMSEC differs from Technical Surveillance Countermeasures (TSCM). TSCM addresses physical bugging, while EMSEC focuses on unintentional electromagnetic leaks. TSCM does not replace proper EMSEC measures.
Purpose of AF Form 4170
AF Form 4170 documents:
- Results of EMSEC assessments.
- Outcomes of EMSEC countermeasures reviews for three separate categories: information systems, communications systems, and cryptographic equipment.
These reviews are conducted independently. The form establishes EMSEC requirements for a specific system or facility and serves as the basis for subsequent EMSEC inspections. It is not an inspection report itself.
Key elements documented on the form include:
- System details and classification level.
- Identification of the inspectable space (often shown on an attached map).
- Required countermeasures (e.g., zoning, TEMPEST-certified equipment, facility shielding, or profile matching).
- Recommendations for containing radiated or conducted emanations.
The form helps IA offices, EMSEC managers, and commanders ensure compliance before systems go operational or during facility modifications.
When and Why to Use AF Form 4170?
Use AF Form 4170 during:
- Initial setup or accreditation of classified information systems.
- Changes to facility layout, equipment, or mission that could affect emanations.
- Periodic reviews as required by command or policy.
- Countermeasures planning for new or modified communications and cryptographic equipment.
Proper documentation on AF Form 4170 supports risk management by defining the “inspectable space” and matching it to appropriate countermeasures, such as:
- Expanding the controlled area.
- Using lower-emission equipment.
- Applying zoning techniques (Facility Zone A, B, C based on attenuation).
- Selecting TEMPEST-certified hardware (when justified, as it can cost 2–5 times more than standard equipment).
Methods for containing emanations include profile matching, zoning, facility testing, or TEMPEST equipment. Costs vary, and the Air Force Certified TEMPEST Technical Authority (CTTA) often validates higher-cost options.
How to Complete AF Form 4170?
While the official form includes detailed instructions (refer to the PDF linked above and supporting manuals like AFMAN 33-214 Volume 2), general steps include:
- Part I – EMSEC Assessments: Provide system identification, location, and assessment details. Attach a map or diagram showing the proposed inspectable space.
- Part II – Countermeasures Reviews: Complete separate sections for information systems, communications systems, and cryptographic equipment. Document specific requirements and justifications.
- Supporting Documentation: Include maps of inspectable space, equipment specifications, and any test results or CTTA coordination.
Always consult your unit’s Information Assurance (IA) office, EMSEC manager, or Cybersecurity personnel for local guidance. Older references point to AFSSI 7700 (Emission Security) and AFSSI 7702 (or related AFSSM 7011) for detailed procedures, though users should verify current Department of the Air Force publications on e-Publishing.
Pro Tip for Air Force Users: Coordinate with your base Cybersecurity Office or CTTA early. They can provide maps, zone ratings, and validation to ensure the form accurately reflects requirements.
Related Air Force Policies and Resources
- AFMAN 33-214 Volume 2 — Provides detailed guidance on EMSEC countermeasures reviews.
- AFSSI 7700 — Core policy on Emission Security.
- AFI 33-203 (older) — Emission Security instruction implementing AFPD 33-2.
- Air Force e-Publishing (e-publishing.af.mil) — Official source for current forms and publications.
- National guidance, including NSTISSM/TEMPEST 2-95 (RED/BLACK Installation Guidance).
EMSEC compliance helps protect national security information and supports mission assurance across U.S. Air Force installations.
Download AF Form 4170?
Access the current fillable or printable version directly from the official Air Force e-Publishing site:
Download AF Form 4170 PDF
For assistance with completion or interpretation, contact your unit security manager, IA office, or the servicing Cybersecurity personnel. They can ensure your documentation meets current standards for classified systems.
Stay compliant – Protect the mission. Proper use of AF Form 4170 strengthens Air Force emission security posture against sophisticated threats targeting compromising emanations.
This article is for informational purposes and is based on publicly referenced Air Force manuals and forms. Always refer to the latest official publications on e-publishing.af.mil and consult your chain of command or IA experts for authoritative guidance.