CLA-2 RR: CR: GC 963183 TPB

Mr. Bruce Leeds
Boeing Satellite Systems
Export/Import Compliance, Legal Staff
P.O. Box 92919
Los Angeles, CA 90009-2919

RE: Spacecraft Control Processor

Dear Mr. Leeds:

This is in response to your request of August 4, 1999, on behalf of Hughes Space and Communications/Boeing Satellite Systems, for a tariff classification ruling on a spacecraft control processor (SCP) used in communications satellites under the Harmonized Tariff Schedule of the United States (HTSUS). We regret the delay in responding.


The product at issue is a spacecraft control processor (SCP), which is used in communications satellites. The SCP is designed with radiation hardening techniques that surpass the required margin for commercial vehicles. This is essential in supporting autonomous spacecraft control and eliminating communication transients and outages.

The SCP design contains the computer resources to provide the on-board intelligence and processing capability to autonomously control a spacecraft through the transfer and operational phases of the mission. Mission unique software routines are installed in Programmable Read-Only Memory (PROM) after the development phase and prior to launch, or, if necessary, reprogrammed into Random Access Memory (RAM) after launch.

The SCP encompasses, among other functions, the attitude control subsystem (ACS), which provides for stabilization and attitude adjustments of the HS-601 spacecraft. Attitude control functions include spinning transfer orbit-nutation control; perigee augmentation; sun/earth acquisition; body stabilized operational orbit; and beacon tracking (as required). The SCP provides the hardware and software processing resources to perform autonomous spacecraft control functions. Major processing functions integrated into the SCP include attitude data processing, attitude control, position control and autonomous spacecraft management, including payload shedding and battery charge and discharge management.

Included in the SCP software are the capabilities to support perigee augmentation, transfer orbit data processing, thruster fire control (including liquid apogee motor burns), sun and earth acquisitions, solar wing positioning, reflector or sensor suite positioning (as required), steady state station-keeping, and all on-site operations. The residence of these and other functions in the microprocessor based SCP allows the spacecraft to operate autonomously as well as in response to ground based control. Included in the design are fault protection hardware and software that ensures single failure protection.

The HTSUS provisions under consideration are as follows:

Direction finding compasses; other navigational instruments and appliances; parts and accessories thereof:

Instruments and appliances for aeronautical or space navigation (other than compasses):

Other: Automatic pilots

Other: Electrical


What is the proper classification of the SCP?


Classification under the HTSUS is made in accordance with the General Rules of Interpretation (“GRIs”). GRI 1 provides that the classification of goods shall be determined according to the terms of the headings of the tariff schedule and any relative Section or Chapter Notes. In the event that the goods cannot be classified solely on the basis of GRI 1, and if the headings and legal notes do not otherwise require, the remaining GRIs may then be applied.

The Harmonized Commodity Description and Coding System Explanatory Notes (“ENs”) constitute the official interpretation of the Harmonized System at the international level. While neither legally binding nor dispositive, the ENs provide a commentary on the scope of each heading of the HTSUS and are generally indicative of the proper interpretation of these headings. See T.D. 89-80. The first step to determining proper classification of the SCP is to determine its proper heading. Although the term “navigation” is not defined in the HTSUS or the ENs, the common usage of this term connotes the science or art of conducting ships (or aircraft) from one place to another, especially the method of determining position, course and distance traveled over the surface of the Earth by principals of geometry and astronomy and by reference to instruments used as aids. See, for example, Oxford English Dictionary, 1987; Merriam-Webster on-line dictionary (

Heading 9014 provides for direction finding compasses, and other navigational instruments and appliances, parts and accessories thereof. The ENs for heading 9014 describe several special instruments for air navigation, at 1602, (II)(C)(1) through (7). These exemplars, however, are not intended to be exclusive, and may expand to include the originally un-thought-of improvements and adaptations to the older technology.

The literature you supplied indicates that the SCP is the primary element in the ACS, which provides for stabilization and attitude adjustments of the HS-601 spacecraft.

Some of the operational modes of the SCP include the ascent phase; the transfer orbit, where thruster active nutation control (TANC) is enabled to stabilize the spacecraft; sun/earth acquisition, where the SCP will provide an automatic capture of the earth along with automatic alignment of the spacecraft to orbit “normal”; on station normal mode, where the earth sensor is used to provide a pitch and roll reference for controlling the spacecraft body; and stationkeeping, that maintains earth reference pointing while generating thruster commands for east-west and north-south delta corrections.

Thus, from the description of the item, the SCP serves as a navigational instrument for the spacecraft and falls within the meaning of the terms of heading 9014, HTSUS. GRI 6, HTSUS, provides as follows:

6. For legal purposes, the classification of goods in the subheadings of a heading shall be determined according to the terms of those subheadings and any related subheading notes and, mutatis mutandis, to the above rules on the understanding that only subheadings at the same level are comparable. For the purposes of this rule, the relative section, chapter and subchapter notes also apply, unless the context otherwise requires.

To ensure that uniformity can be maintained at the subheading level, GRIs 1 to 5 governs classification to subheading levels within the same heading. After determining the appropriate heading in accordance with the first five rules, we then apply the GRIs again, to the appropriate subheading.

When making comparisons of subheadings, we compare the same level six-digit to six-digit, or eight-digit to eight-digit subheading, also taking into consideration section and chapter notes at the subheading level, unless the context otherwise requires.

Subheading 9014.20, HTSUS, provides for instruments and appliances for aeronautical or space navigation (other than compasses). Further breakdowns of that subheading include 9014.20.40, HTSUS, which provides for automatic pilots and 9014.20.60, HTSUS, which provides for other electrical instruments and appliances for aeronautical or space navigation.

In applying GRI 3(a) at the subheading level through GRI 6, the heading that provides the most specific description shall be preferred to headings that provide a more general description. Relevant ENs on p. 1603 describe automatic pilots, also called autopilots, as apparatus that temporarily replace the pilot by controlling the equilibrium and flight of the aircraft in accordance with a pre-established setting. They consist chiefly of direct-operated or servo-motor controls (usually hydraulic motors which replace the pilot’s movements), and of automatic acting apparatus (high-speed gyroscopes) which co-ordinate instrument readings and the action of the servo-motors.

Modern flight controls, however, now use digital computers, which accept data from multiple sensors to control unstable aircraft with multiple feedback loops operating several aerodynamic control surfaces. The provision for automatic pilots describes a commodity eo nomine, by name. In the absence of a contrary legislative intent, judicial decision, or administrative practice, an unlimited eo nomine designation will include all forms of the named article. Autopilots fly an aircraft in the same manner as a pilot. Autopilots are also recognized for use with unmanned craft such as missiles and torpedoes and launch vehicles used to place spacecraft into orbit and ballistic missiles onto their trajectories. See “Autopilot,” McGraw-Hill Encyclopedia of Science & Technology, Vol. 2, p. 273 (1987).

We note that the SCP contains a central processing unit (CPU). This CPU contains memory that supports the various functions programmed into the vehicle firmware (PROM) and may also be programmed from the ground (RAM). Custom designed SOS/CMOS VLSI and hybrid circuits that perform the input/output (I/O) processing functions optimally support the CPU. The primary function of the components, in this case, appears to be the autonomous control of the space vehicle.

Based upon the functions and capabilities of this device to autonomously control the spacecraft’s direction and attitude, the SCP meets the terms of subheading 9014.20.40, HTSUS, as an automatic pilot. Its function is basically to serve as the “brain” of the space vehicle, and replace the need for a human pilot or a constant stream of directions sent from the ground. Since this term is more specific than 9014.20.60, instruments…for…space navigation, other, other, electrical, the SCP is properly classified under the former subheading. HOLDING:

For the reasons stated above, the SCP is a navigational instrument or appliance of heading 9014. Under the authority of GRI 3(a), applied at the subheading level through GRI 6, the SCP is an automatic pilot classifiable in subheading 9014.20.40, HTSUS.


John Durant, Director
Commercial Rulings Division