Identify Friend or Foe

A Current Resource Guide for Unmanned Aircraft

Your Ultimate Resource for Identify Friend or Foe (IFF) Capability on Unmanned Aircraft for NATO and Allied Forces

Implementing Mode 5 IFF on unmanned aircraft? With the newer AIMS 17-1000 Mark XIIB requirements and new products coming online, we’ve curated the industry’s best information about Mode 5 IFF on unmanned aircraft here for you. 

Topics discussed here include:
The Mode 5 IFF Requirements for Unmanned Aircraft
Mode 5 IFF: Old and New Specifications
Comprehensive Mode 5 IFF for Unmanned Aircraft
Reduced Mode 5 IFF Requirements in Appendix G
Additional Onboard Technologies to Consider
Crypto Computers for Mode 5 IFF
Currently Certified Mode 5 IFF Transponders
Recent Articles About IFF on UAVs

what is the iff requirement for unmanned aircraft?


For military aircraft programs that support NATO and allied military forces, an updated Identify Friend or Foe (IFF) Mode 5 requirement was recently enacted, requiring vehicles to update by July 1, 2020. Many of the large manned aircraft platforms have complied by using traditional commercial avionics-sized transponders, and now smaller UAVs and UAS can comply with new certified IFF micro transponders.

IFF transponders must be certified by the DoD AIMS office to the Mark XIIB standard as specified in AIMS 17-1000. NATO has ratified the same Mode 5 standard as documented in STANAG 4193.

IFF certified micro transponders are required for use in NATO military equipment as well as other allied countries. Identify Friend or Foe is an air-combat identification system which positively distinguishes friendly from enemy aircraft, reducing fratricide and unauthorized incursions. The technology employs spread-spectrum radio transmissions that are difficult for adversaries to intercept or jam and has secure data encryption.


Unmanned aircraft can comply either with the comprehensive IFF specification or to the specification’s newer Appendix G, with reduced requirements for UAVs.

mode 5 Identify Friend or Foe:

old and new specifications

IFF was in effect for decades as Mode 4 IFF. Today this legacy technology is replaced by Mode 5 IFF with updated specifications that dictate stronger encryption, different response prioritization in the transmitter, and GPS information about target aircraft locations.

Most traditional certified aircraft transponders are certified to the older level of Mode 5 IFF, AIMS 03-1000 Mark XIIA. The newer specification is AIMS 17-1000 Mark XIIB. Aircraft will need to update to the newer specification, requiring significant rework in older transponders. Right now, Sagetech’s micro transponder is the only transponder certified to AIMS 17-1000 Mark XIIB. Below are the high level differences:

Previous IFF Specification
Current IFF Specification
Military IFF Modes Included
IFF Mode 4 and Mode 5
IFF Mode 5
Specification Number
DoD AIMS 03-1000
DoD AIMS 17-1000
Mark Designation

Comprehensive IFF for Unmanned Aircraft

Within these specifications, several functionalities are required for certification to AIMS 17-1000 Mark XIIB for use on military mission programs.


appendix G:

reduced mode 5 identify friend or foe requirements

Intended for very small UAS, Appendix G of the Mode 5 IFF specification offers some concessions for UAV transponders:

  • Lower transmit power (reduces range)
  • Single antenna (reduces visibility)

The advantages of Appendix G are typically:

1. A smaller unit. Lower power and single antenna support may reduce the size and weight of the transponder.

2. Less power consumption. 

However, on balance, it’s important to consider the downsides. Mode 5 IFF transponders that are certified just to Appendix G may reduce two important use cases for your aircraft:

1. Multi-mission suitability. If your aircraft may do longer distance duty as well as shorter distance duty, transponders that only meet the reduced requirements of Appendix G will put this aircraft at a competitive disadvantage for the longer distance missions.

2. Avionics conformity across all an OEM’s UAV aircraft lines.  If an OEM offers UAVs of different sizes and missions, using a micro transponder certified to the full AIMS 17-1000 Mark XIIB without the Appendix G deviation will preserve a conformity of avionics design across all aircraft, from Group 2 up, saving design, test, and procurement time and cost.

3. Visibility. With just a single antenna, the drone may lose visibility from aircraft flying either above or below. This could lead to drone vulnerability to fratricide and would reduce the ability of warfighters to recognize hostile threats. 


additional onboard technologies to consider

for iff systems

Mode 5 IFF transponders can include additional capabilities that help future proof your aircraft. Some of these include:

  • Integrated ADS-B In. While Mode 5 IFF will be used in a military combat or training mission, if a military UAV will fly in the national airspace system (NAS) at all for a non-military mission, it should include ADS-B In capability for situational awareness and communication with ATC and TCAS. 

  • Upgrade capability. New specifications are emerging for Mode 5 Level 2B In and Out. Micro IFF Mode 5 transponders should carry an upgrade path to include these future requirements.

  • Small size and weight. While some UAV programs have incorporated commercial aircraft-sized equipment to comply with Mode 5, today UAV programs have the option of using certified micro-transponders that are up to 9x smaller and 6x lighter than traditional “small sized” transponder solutions.

  • External crypto (appliqué). Using an external crypto computer simplifies the logistics of maintaining and operating controlled hardware.

Crypto Computers for mode 5 iff

External crypto computers execute the IFF algorithms for Mode 5 IFF. Current suppliers of Mode 5 IFF crypto computers that operate with Mode 5 IFF certified transponders include the Raytheon KIV 77 and the Leonardo SIT-2010. Additional miniature cryptos are currently in development.  


Currently Certified Identify Friend or Foe (IFF) Transponders

sagetech MX12B

Currently the only IFF transponder of any size certified to AIMS 17-1000 Mark XIIB


A reduced sized transponder (RST), certified to AIMS 03-1000 Mark XIIA

Raytheon Units

Multiple units for manned aircraft, certified to AIMS 03-1000 Mark XIIA

recent articles on mode 5 identify friend or foe topics

We’ll post reference and editorial articles here as we find them for you.

Unmanned Systems Technology: “IFF Transponders”
SUAS News: “Implementing Mode 5 IFF Transponders into Unmanned Systems: What to Know.”