USML Category XII: guidance, navigation and components

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1. Guidance and navigation

Guidance, navigation and the components behind them make up the second half of Category XII of the United States Munitions List (USML), "Fire Control, Laser, Imaging, and Guidance Equipment" (22 CFR 121.1). Paragraph (d) deals with guidance and navigation, paragraph (e) with parts and components, and paragraph (f) with technical data. Fire control, lasers and night vision are covered in Category XII, fire control, lasers and night vision.

Paragraph (d)(1) covers guidance or navigation systems such as inertial navigation systems, inertial reference units and attitude and heading reference systems (22 CFR 121.1). They are caught by any one of four performance tests, each measured without positional aiding references. One is a circular error probability at fifty percent (CEP50) of position error rate better than 0.28 nautical miles per hour. Another is heading error or true north determination better than 0.28 mrad secant (latitude). A third is a CEP50 of position error rate less than 0.2 nautical miles in an 8 hour period. The fourth is meeting specified performance at linear acceleration above 25g.

The entry carries the (MT) annotation for systems designed for long-range rockets, missiles or unmanned systems, or incorporating MT-designated accelerometers or gyroscopes (22 CFR 121.1). The Missile Technology Control Regime Annex is what that marker refers to (22 CFR 120.10). Guidance sets for rockets and missiles are sent to Category IV, and inertial measurement units are listed in paragraph (e) (22 CFR 121.1).

2. Satellite navigation receivers

Paragraph (d)(2) covers Global Navigation Satellite System (GNSS) receiving equipment in four groups (22 CFR 121.1). The first is equipment specially designed for military applications. The second is Global Positioning System receivers specially designed to encrypt or decrypt protected positioning service signals, with Y-Code and M-Code as examples. The third is equipment specially designed for use with the controlled antennas of Category XI, and the fourth is equipment specially designed for rockets, missiles or unmanned systems able to deliver at least 500 kg to at least 300 km.

Paragraph (d)(3) covers GNSS anti-jam systems specially designed for those Category XI antennas (22 CFR 121.1). Paragraphs (d)(4) and (d)(5) cover mobile relative gravimeters with automatic motion compensation and accuracy better than 0.4 mGal, and mobile gravity gradiometers at a stated accuracy and spatial resolution of 50 m or less. Paragraph (d)(6) covers developmental guidance or navigation systems funded by the Department of Defense. The usual production, jurisdiction and dual-use exclusions apply, and so does the October 12, 2017 start date.

The gravity sensors carry their own (MT) conditions (22 CFR 121.1). Gravimeters are annotated if designed for airborne or marine use with a time to steady-state registration of two minutes or less, and gradiometers if designed for airborne or marine use.

3. Sensors and optics components

Paragraph (e) lists twenty-four groups of parts and components (22 CFR 121.1). Some serve the fire control and imaging articles. They include lasers and laser stacked arrays specially designed for defense articles, and night vision or infrared cameras specially designed for defense articles, meaning camera cores with enough electronics to output a signal once powered. Infrared focal plane arrays, their read-out integrated circuits, dewar cooler assemblies and cryostats are listed, along with charge multiplication arrays above a stated responsivity.

Second generation and greater image intensifier tubes specially designed for defense articles are covered (22 CFR 121.1). A note defines second and third generation tubes by peak response between 0.4 and 1.05 micron. They use a microchannel plate with a hole pitch of less than 25 microns and either an S-20, S-25 or multialkali photocathode or a GaAs, GaInAs or other III-V compound semiconductor photocathode. Infrared lenses, mirrors, filters and coatings specially designed for the category are included, as are gimbals, processing electronics and near-to-eye displays.

4. Inertial components

Inertial measurement units specially designed for defense articles are covered, and so are GNSS security devices such as Selective Availability Anti-Spoofing Modules (22 CFR 121.1). Accelerometers are caught with bias repeatability better than 10 µg and scale factor repeatability better than 10 parts per million, or if able to measure greater than 100,000 g. The (MT) designation does not include accelerometers designed to measure vibration or shock. Gyroscopes and angular rate sensors are caught at an angle random walk better than 0.001 degrees per square root hour, or for mechanical types, a bias repeatability better than 0.0015 degrees per hour. Mechanical types carry the (MT) annotation if their rated drift stability is less than 0.5 degrees per hour in a 1 g environment, or if specified to function above 100 g. Drift rate is the part of gyro output independent of input rotation, expressed as an angular rate.

Notes define the terms (22 CFR 121.1). Repeatability is the closeness of agreement among repeated measurements under the same conditions when changes or idle periods occur between them. Bias is the accelerometer output when no acceleration is applied, and scale factor is the ratio of change in output to change in input. Both are measured as one sigma against a fixed calibration over a year. Developmental intensifier tubes, arrays, read-out circuits and inertial sensors funded by the Defense Department are also covered.

5. Classified items, technical data and approval

One entry, with an asterisk, catches any part that is classified, contains classified software, is manufactured using classified production data, or is being developed using classified information (22 CFR 121.1). The asterisk designates it as Significant Military Equipment (22 CFR 120.10). Paragraph (f) controls technical data and defense services directly related to paragraphs (a) to (e), and classified technical data about items in Export Control Classification Numbers 7A611, 7B611 and 7D611 (22 CFR 121.1).

Paragraph (x) is limited to EAR items in the same purchase as Category XII articles (22 CFR 121.1).

Key terms

CEP50	Circular error probability at fifty percent, used for the navigation drift tests.
GNSS	Global Navigation Satellite System, whose military and encrypted receivers are controlled here.
Bias repeatability	How closely repeated readings agree for the output given when no acceleration is applied.
Angle random walk	A gyroscope performance measure, controlled here at better than 0.001 degrees per square root hour.
Camera core	A night vision or infrared camera with enough electronics to output a signal once powered.

Every statement above links to the document behind it. The full source list for this piece is on the sources page.

This page describes public United States government programs for general information. It is not legal, regulatory or procurement advice, and it does not address the facts of any particular case.

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