Milestone-Proposal:Shuttle Training Aircraft

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Docket #:2017-05

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To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? No

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? No

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? No

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:


Title of the proposed milestone:

Space Shuttle Training Aircraft Avionics and Controls, 1976

Plaque citation summarizing the achievement and its significance:

N946NA, the first NASA Shuttle Training Aircraft (STA), produced by Grumman Aerospace Corporation and Sperry Flight Systems, began flying in 1976. A model-following flight control computer and modified control surfaces gave her the flight characteristics of a Space Shuttle. Each Shuttle pilot performed hundreds of STA landings before landing a Shuttle. After 35 years and 12,000 hours of flight, she retired at the Texas Air and Space Museum.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

In what IEEE section(s) does it reside?

Region 5 - Panhandle Section

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

IEEE Organizational Unit(s) arranging the dedication ceremony:

IEEE section(s) monitoring the plaque(s):

Milestone proposer(s):

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

10001 American DrAmarillo TX 79111-1213-101.714409 35.214393

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. Texas Air and Space MuseumCurrently located on the property of Rick Husband International Airport. A new campus is under development, adjacent to the airport. The new site is 20 acres, with 5 acres under roof. In the airport's terminal, there is a statue of astronaut and Amarillo native Rick Husband who died in the Columbia space shuttle disaster on Feb. 1, 2003. Rick trained on N946NA prior to becoming a shuttle commander."Built in 1976 and flown by astronauts (including Rick Husband) for thousands of hours, NASA 946's flying days are over. At 11:30 AM on the morning of September 21, 2011, two NASA Gulfstream II aircraft landed at the Rick Husband Amarillo International Airport and taxied to the Texas Air & Space Museum. The crew of one Gulfstream--N946NA--shut the aircraft down--for the last time, exited the aircraft--for the last time, and said goodbye to a trusted workhorse that had served NASA well for 35 years. 946's crew then boarded her sister ship and flew back to Houston, leaving 946--plus, the aircraft's manuals, logs, charts, handbooks and headsets--in a place where people of the Texas Panhandle and visitors from around the world could see, touch and feel a major contributor to our nation's space program." (

Are the original buildings extant?


Details of the plaque mounting:


How is the site protected/secured, and in what ways is it accessible to the public?


Who is the present owner of the site(s)?

Texas Air and Space - tenant group. New location - nearby - will be fully owned by the museum.

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

The Space Shuttle program and vehicle grew out of NASA's 1969 Space Transportation System (STS) project which was tasked with producing a low-earth orbit reusable spacecraft. The concept, and reality, of a highly reusable transportation and supply vehicle were magnitudes more complex than any previous space craft program. That included a controlled, unpowered landing on conventional runways, but at much steeper approach angles and much higher speeds than conventional aircraft. The Shuttle Training Aircraft was the vehicle needed to train the astronauts for actual shuttle landings. A high degree of fidelity in the ability of the STA to give the astronauts a realistic sense of shuttle landings was paramount. (ref. 3) Ground-based simulators, like the Vertical Motion Simulator provided a more complete, and acceptable, simulation for the final approach and touchdown but could not produce the large-motion maneuvers needed for simulating the descent and energy management maneuvers beginning at 30,000 feet or higher.

What obstacles (technical, political, geographic) needed to be overcome?

Compared to the crew capsules of prior manned space flights, the shuttle was a completely different bird. It was designed to transport both crew and cargo for stand-alone missions as well as missons to the International Space Station. It was designed for reuse with minimal rework, including refurbishing its three liquid fuel engines, between missions. It was not the final stage on a multistage launch vehicle—it was, along with the external tanks for fuel and oxidizer, an integral part of the launch vehicle first stage (with the two solid fuel booster rockets providing most of the thrust for the first two minutes.) On re-entry to the atmosphere, it dropped out of the sky like a brick with short wings. Go-around, or powered flight for short-fall approaches to the runway, was not an option. (ref 2) The potential and kinetic energy within the terminal area, had to be accurately computed, constantly monitored, and precisely managed (Terminal Area Energy Management - TAEM). In the TAEM phase, a closed loop, computerized control system flew the shuttle to a point where the pilot took control for final approach, touch-down, and roll-out. The STA was critical for developing these new flying skills in shuttle commanders prior to their landing actual shuttles. Each astronaut had to complete 500-1000 simulated landings in an STA before taking command of a shuttle. (refs 3,4)

What features set this work apart from similar achievements?

The re-entry vehicles in earlier space flights were ballistic in nature—from the time of leaving orbit until the drag chutes were deployed, the capsules were in free-fall. By no definition was the Shuttle an airplane, but it was designed to have a measure of aerodynamic control sufficient to transition from its free-fall to a hot landing and roll-out. In earlier advancements of powered aircraft, conventional or experimental, the differences in aircraft behavior were incremental, not monumental. Most any pilot with sufficient flight experience could transition to a different aircraft with minimal instruction and additional flight hours. The Shuttle, and, hence the Shuttle Training Aircraft, would require pilot skills, and a computer-augmented control system well beyond those required for the T-38 Talon that was the standard for maintaining basic flying skills of the astronauts. Earlier considerations for the STA included the Boeing 737. It met all the requirements for performance in the demanding approach and landing phase, but was deemed too expensive. (ref. 6)The Grumman Gulfstream II was chosen instead, amid concerns for the GII's ability to withstand the forces that would result from shuttle emulation. The 30+ year operational life of all four Shuttle Training Aircraft in NASA's fleet validated the GII's airworthiness and the computerized guidance system's capabilities for the mission.

In contrast to earlier model-following implementations, including ground-based simulators, the STA would be required to match not just small perturbations off a trimmed flight pattern, but large motions that occur in the critical descent phase from 40,000 feet to runway threshold. A full six-degrees-of-freedom simulation within the on-board digital computer would be compared to actual STA location and dynamics, then commands would be computed and applied to not only the standard rudder, aileron, and elevator surfaces, but added surfaces for direct-lift, side-force, and thrust reversal to reduce model-following error. [ref 8] (Feed-forward signals would later be added to minimize pitch and roll delays experienced in early flight testing. [ref 5]) The only thing missing was the seat-of-the-pants thump of wheels hitting the runway. (The Vertical Motion Simulator at NASA Ames Research Center provided that experience, as well as roll-out steering and braking simulation. And, it did provide a degree of large motion capability but not approaching the full range of the descent phase. [ref 2])

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

1. The Shuttle Training Aircraft (STA) was a NASA training vehicle that duplicated the Space Shuttle's approach profile and handling qualities, allowing Space Shuttle pilots to simulate Shuttle landings under controlled conditions before attempting the task on board the orbiter. The original Flight control system was a Sperry Flight Systems 1819B with all of the associated peripheral ATR boxes that became all too familiar. The Parallel Processor system added an Rolm 1666B mini-computer. These computers were mini's operating at 10 MHz clock speed, multi-clock machine cycle, and utilizing magnetic core memory. Mass storage was a 9-track Reel-to-Reel deck. In this model only the left seat was a Fly-By-Wire system. The right seat had standard G-II control. These two totally dis-similar architecture machines were interfaced to form a true asymmetrical dual parallel processing system. This development led to the development of the Advanced Digital Avionics System (ADAS)which could be populated with a total of 16 parallel processors. Two of the original processors were custom Sperry 1819 based microprocessors. 14 were to be populated with Motorola 68010 processor card in a Sperry ATR form factor card, but VME protocols.

The original Flight control system was a Sperry Flight Systems 1819B with all of the associated peripheral ATR boxes that became all too familiar.

The STA was particularly critical for Shuttle pilots in training because the Orbiter lacked atmospheric engines that would allow the craft to "go around" after a poor approach. After re-entry, the Shuttle was a very heavy glider (it was sometimes referred to as a 'flying brick') and as such had only one chance to land.

2. Space Shuttle Landing and Rollout Training at the ... - NASA American Institute of Aeronautics and Astronautics journal article outlining the approach and landing requirements of the shuttle and the role of the Shuttle Training aircraft and Vertical Motion Simulator in training shuttle pilots. Full reference and text to be provided in supporting materials.

3. Karon Woods NA131/Crew Survival & Operations Specialist NASA JSC S&MA Flight Safety Office

I've drafted some history on the STAs in case any of it is of interest. The STAs are and will always be my girls, each with a unique personality. Of my 28 years with NASA, I spent my first ten as the Shuttle Training Aircraft Project Engineer (1985-1995). I was responsible for the STA fleet maintenance and modifications. I've had a lot of really challenging assignments at NASA , but being the STA project engineer was my favorite. Working on those aircraft gave me the experience and insight that allows me to perform risk assessments, failure investigations, and system and crew survivability analyses, to name a few. Not many engineers get to be actively involved in the design, modification, manufacture, implementation, test, verification, inspection and maintenance of all aspects of a system, much less an entire fleet of aircraft. It was an engineer's dream job. However, the girls are much more interesting than I am. The Shuttle Training Aircraft were specially modified aircraft developed to support training the approach and landing phase of the Space Shuttle Orbiter. When NASA retired the fleet of four highly-modified Gulfstream II, in 2011, at the end of the Shuttle program, it was the end of a highly successful in-flight crew training program. In 1976, NASA 946 and NASA 947 rolled off Grumman's Gulfstream assembly line with significant modifications to flight controls, engines, thrust reversers, and landing gear, to create the first Shuttle Training Aircraft (STA). After outfitting them with controls, displays and visual cues to simulate the Shuttle flight console, and onboard avionics and computers to model the approach and landing phase of the Shuttle profile, they were used to train the first to the last Shuttle flight crews, and all Shuttle crews between. Before flying the Shuttle, an astronaut was required to complete 500 dives in the STA, and maintain currency in the aircraft. Every astronaut that flew on the Shuttle, first flew on the STA. The Shuttle pilots and commanders always stated in their mission debrief how well the STAs prepared them for their Shuttle landing experience. From their perspective, the STA simulations matched the Orbiter landings look, feel and performance. We exceeded the adage "train like you fly, fly like you train." Not bad for making a fleet of the Cadillac's of business jets fly like a man-hole cover; 30,000 feet altitude to the ground in less than three minutes. Later, NASA added NASA 944, then NASA 945. Once flown as corporate aircraft, NASA 944 and 945 were modified into STAs in 1984 and 1989, respectively. Before becoming an STA, NASA 945 also supported the Propfan testing at NASA's Glenn Research Center with a third engine installed on the original wing. The wing was replaced during the STA modification. The only significant design modification difference between NASA 946 and 947 and NASA 944 and 945 was the elimination of the side force controllers. They were two very large airfoils mounted perpendicular to the wing lower surface that were intended to augment yaw. The side force controllers were removed from the STA design because the consequence of a gear-up landing overshadowed the benefit to the simulation. Throughout their lives, the STAs were maintained at NASA's Johnson Space Center (JSC) Aircraft Operations in Houston, TX. As advancements in avionics and mathematical simulation techniques drove changes to the Orbiter design, the engineers and technicians in JSC's Aircraft Operations continued to update the simulation models and avionics to the STAs, including the implementation of a glass cockpit. There were challenges. When Grumman informed us that the STAs were limited to a life of 5000 hours, we implemented a service life extension program. We instrumented the aircraft so we could characterize the operational parameters, then modeled the aircraft to determine critical locations and parameters. With the results of this program, we implemented an inspection and functional test plan to ensure continued, safe operation of the STAs. All of the aircraft exceeded 8000 hours without failure. NASA 946 exceeded 12,000 hours and NASA 947 retired with over 13,000 hours. The program ended with 39,769.3 hours, 162,863 simulated Orbiter approaches and 28,996 landings, and no failures of critical structure. Like I said, they are my girls. NASA 947 now lives at the Evergreen Flight Museum in Portland, Oregon. NASA 946 has taken up residency with the Texas Air and Space Museum at Rick Husband Amarillo International Airport in Amarillo, Texas. NASA 945 will soon be on display at the United States Space and Rocket Center in Huntsville, Alabama. NASA 944 is on static display at NASA's Dryden Flight Research Center. If you get a chance to visit them, remember that they always returned our flight crews and astronauts safely, never complained, and asked very little from us, well, any lady appreciates a nice coat (of paint). Tell them I said hi.

4. Excerpts from

Prior to a Shuttle mission, a commander has to complete 1,000 STA landings. The STS-114 commander and pilot, Eileen Collins and Jim Kelly, will continue STA training on a weekly basis until launch. Such thorough practice leads to confident astronauts and successful Shuttle landings -- not to mention great feedback for the STA teams.

"Shuttle astronauts come back and tell us it felt like they had done it a thousand times before," Nickel said.

"It is some of the best training we have," Collins said.

5. Excerpts from

The interior of the STA differs significantly from a stock Gulfstream II. For starters, the left side of the standard G-II cockpit was completely moved to the right side. Typically, the aircraft is flown from the right seat and the controls on the left side are completely inoperative. The left side has been outfitted with a full set of space shuttle controls: a hand controller for pitch and roll rate commands; rudder pedals to command a sideslip angle; and shuttle instruments — including attitude indicators and tape meters for airspeed, altitude, and rate of descent. Both sides of the cockpit are equipped with head up display (HUD) devices. A large computer in the main cabin is the heart and soul of the STA.

During this climb the FSE prepares the computers and avionics for simulation mode operation.

he STA successfully simulates the subsonic portion of the shuttle's glide to landing. It matches the shuttle's attitude, angle of attack, airspeed, roll and pitch response, and that important eye height at touchdown. The Sperry digital computer, coupled with faster-acting hydraulic actuators and the bidirectional flaps, makes this simulation possible.

The STA provides a model-following simulation. To the pilot it simply means that his input on the rate command stick is analyzed by the computer and interpreted as to what pitch or roll rate of the shuttle is being requested. The computer then commands the proper control surface on the STA to move, producing the desired shuttle motion.

6. Young, John W.; Hansen, James R. (2012). "IV: The Shuttle Era". Forever Young: A Life of Adventure in Air and Space (Kindle eBook). University Press of Florida. I went to Boeing in Seattle to see if its 737 airliner could be used to simulate the orbiter, particularly on its final high-altitude overhead approach to landing. We found that it could be done in the 737 simulator if the pilot could use reverse thrust and all the machine’s drag devices at a speed of 300 knots. The real drawback was the expense of the Boeing 737, which we could not afford.

7. Note - need to coordinate with other possible journal reference after getting access to the two articles.

8. 1974 IEEE Conference on Decision and Control including the 13th Symposium on Adaptive Processes, Shuttle Training Aircraft Digital Avionics System. A journal article by Roger Keller and John Williams (Sperry Flight Systems) 1974 Copy accessed by Robert Colburn.

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