Boeing 747 Shuttle Carrier Aircraft (SCA)

A jumbo with a spacecraft on its back – hardly any image from aviation has stuck as firmly. The Boeing 747 Shuttle Carrier Aircraft, SCA for short, was the solution to a very practical problem: after landing, the orbiters of the Space Shuttle program could not fly back to the launch site on their own. So a converted jumbo carried them across the US and, once, even to Europe. Here you will learn where the two aircraft came from, what was changed on them, what a flight with an orbiter felt like, how to tell the two apart and where you can visit them today.

What is the Shuttle Carrier Aircraft?

The SCA is not a type of its own but a conversion of the Boeing 747-100. NASA bought two used jumbos and had Boeing prepare them to its own specifications for a single job: transporting a Space Shuttle orbiter safely on the fuselage. What is always meant is the winged spacecraft itself, without the external tank and solid boosters.

This was necessary because, after returning from space, an orbiter landed like a glider and had no engines of its own for cruise flight. If it did not land at Kennedy Space Center in Florida but, say, at Edwards Air Force Base in California, it had to get back across the continent. The routes between shipyard, test site and launch site also ran via the jumbo. Add special tasks such as the approach and landing tests of 1977 and, at the end, the ferry flights to the museums.

Why a 747 of all things?

NASA also examined the Lockheed C-5 Galaxy as a carrier. In the end, quite a bit spoke for the jumbo: as a low-wing aircraft, the 747 has a free fuselage back on which a large load can be fastened well. A high-wing aircraft like the C-5 would have been less suitable for that. There was also an organizational point – NASA could own the 747 itself, whereas a C-5 would have remained US Air Force property.

The two aircraft: NASA 905 and NASA 911

Both aircraft have an airline past, and both are based on the first jumbo generation with Pratt & Whitney JT9D engines.

Feature	NASA 905	NASA 911
Registration	N905NA	N911NA
Base type	747-123 (747-100)	747SR-46 (747-100SR)
Previous owner	American Airlines	Japan Airlines
First flight as an airliner	October 1970	August 1973
With NASA	from 1974	from 1988, in service from 1990
Upper deck windows per side	2	5
Retired	2012	February 2012
Today	Space Center Houston	Joe Davies Heritage Airpark, Palmdale

NASA 905: the pioneer from the American Airlines fleet

The older aircraft flew for American Airlines from 1970. In the early 1970s, air traffic had grown more weakly than hoped, and many airlines had more jumbo seats than they could fill. American gave the aircraft up, and in 1974 it went to NASA. There it initially served not as a shuttle carrier but as a research aircraft for studies on wake turbulence – that is, on the air vortices that large aircraft trail behind them.

The conversion to a shuttle carrier followed in 1976. Striking: in the 1970s, N905NA still wore American Airlines’ cheatline stripes. The well-known NASA livery with a white fuselage and a blue cheatline came later; by 1983, on the European flight, it had already been applied.

NASA 911: reinforcement after the Challenger accident

After the loss of Challenger in January 1986, NASA no longer wanted to depend on a single aircraft for transporting the orbiters. In 1988 it therefore acquired a second 747, this time a 747SR from Japan Airlines. The SR version (“Short Range”) had been built for busy Japanese domestic routes and had a structure for an especially large number of takeoffs and landings. After a conversion similar to NASA 905’s, the aircraft entered service in 1990. It flew its first mission in 1991: it brought the new Endeavour from Palmdale in California to Kennedy Space Center.

What was changed on the jumbo

From the outside, an SCA at first looks like a normal 747-100. You only spot the most important changes on a second look – and some are entirely inside.

For the 1977 test flights, NASA 905 got one more special detail: an emergency escape slide behind the cockpit, by which the crew was to leave the aircraft in an emergency. After the tests it was removed again, because of the concern that people bailing out could get into an engine.

And one more curiosity: without an orbiter on its back, the center of gravity of the converted jumbo was no longer quite right. Empty flights therefore needed ballast so that the aircraft was properly balanced.

Flying with a spacecraft on its back

An orbiter on the fuselage creates enormous additional drag. Flight performance with the load was correspondingly modest: about Mach 0.6, and an altitude of no more than about 15,000 feet. Range shrank to about 1,000 to 1,150 nautical miles, depending on the source – without an orbiter the aircraft went many times farther. A crossing of the US from California to Florida therefore meant several fuel stops.

On such flights, four people sat in the cockpit: two pilots and two flight engineers. Without an orbiter, one flight engineer was enough. Preparing a ferry flight was elaborate: about a week of work for a team of around 170 people is on record. The orbiter was placed on and lifted off with special crane rigs at the shuttle sites.

1977: Enterprise and the approach and landing tests

NASA 905 played its most famous role in the Approach and Landing Tests (ALT) at Edwards Air Force Base in California. The test article was Enterprise – an orbiter that was never to fly into space but served to test glide and landing behavior.

The program ran in three stages. First came taxi tests on the ground. From February 18, 1977, captive-carry flights followed, in which Enterprise stayed firmly on the jumbo – first uncrewed, from June 1977 with a crew. The highlight was the five free flights: in these, Enterprise was separated from the jumbo in the air and glided to a landing on its own. The first free flight took place in August 1977, the last on October 26, 1977. The astronauts in the orbiter cockpit included Fred Haise and Gordon Fullerton.

After that, NASA 905 became the program’s regular transport aircraft. It brought orbiters from the manufacturer Rockwell to the launch site, fetched them back to Florida after landings in California and flew them to overhauls.

1983: the Space Shuttle in Europe

For spotters in Germany, one chapter is especially exciting: in spring 1983, NASA 905 flew Enterprise across the Atlantic. Because of the limited range with an orbiter, it went in legs: fuel stops were at Goose Bay in Canada and at Keflavík Airport in Iceland, among other places, before the pair reached England.

The goal of the trip was the 1983 Paris Air Show, which traditionally takes place at Paris Le Bourget Airport. How the show works today and how to spot there is covered in the article on the Paris Air Show at Le Bourget. In May 1983 – German sources say Pentecost – the combination could also be seen at Cologne Bonn Airport. According to overview accounts, Enterprise’s tour in 1983 and 1984 also included stops in Italy and Canada; exact places and dates of these stops are not documented consistently everywhere.

Standing at Cologne Bonn Airport today, you can hardly imagine the scene. If you want to spot there yourself, you will find the current options in the Cologne Bonn spotting guide and at the Cologne Bonn Airport observation deck.

The last flights: orbiters on their way to the museum

With the end of the Shuttle program in 2011, the SCAs’ final task began: bringing the orbiters to their display locations. NASA 911 was no longer involved. The aircraft flew one last time on February 8, 2012, to NASA’s Dryden research center at Edwards Air Force Base and was used there as a parts donor, including for the SOFIA infrared observatory, also a converted 747.

NASA 905 flew the ferry flights:

Date	Orbiter	Destination
April 17, 2012	Discovery	Washington Dulles, for the Udvar-Hazy Center
April 27, 2012	Enterprise	New York JFK, for the Intrepid Museum
September 19–21, 2012	Endeavour	Los Angeles, for the California Science Center

Before landing, the pair flew low-altitude victory laps over the cities each time. Discovery stands today in the Steven F. Udvar-Hazy Center at Washington Dulles Airport. Enterprise landed at New York JFK Airport, was later transported onward by barge and is on display at the Intrepid Museum in New York. Endeavour flew to California with stopovers in Houston (Ellington Field) and at Edwards Air Force Base, among other places, landed at Los Angeles Airport and then rolled through the streets of Los Angeles and Inglewood to the museum. Atlantis stayed at Kennedy Space Center and needed no flight.

After the Endeavour delivery, NASA 905 flew to the Dryden center in September 2012. Here too, stripping it for SOFIA was planned, but only a few parts proved usable – lucky for posterity.

How to follow such one-off ferry flights live today is explained in the article on delivery and ferry flights.

How to recognize a Shuttle Carrier Aircraft

You will no longer meet an SCA in flight. But in historic photos, slides or at the museum, a close look is still worthwhile – especially if you want to know which of the two aircraft you have in front of you.

To tell the two SCAs apart, the upper deck helps: N905NA has two windows per side, N911NA five. How to tell the other jumbo versions apart is shown in the guide How to tell the Boeing 747-100 to 747-8 apart.

Where to see the shuttle jumbos today

Both aircraft are preserved – and both are open to the public.

NASA 905 at Space Center Houston

In 2013, NASA decided to display NASA 905 at Space Center Houston, the visitor center of Johnson Space Center. The aircraft flew to Ellington Field in Houston for this, was disassembled and brought to the museum in several large pieces. In August 2014, a heavy-lift crane placed the shuttle replica Independence on its back. The replica previously stood under the name Explorer at the Kennedy Space Center visitor complex. The “Independence Plaza” exhibit opened in January 2016. The special thing: you can walk through both the jumbo and the shuttle replica there.

NASA 911 in Palmdale

NASA 911 has stood since September 2014 on loan from NASA at the Joe Davies Heritage Airpark in Palmdale, California – an open-air museum next to Air Force Plant 42, where the orbiters were once built and serviced. The park also shows a number of retired military and test aircraft. It is not open every day; check the current opening days directly with the operator before your visit.

Place	What you see	Note
Space Center Houston	NASA 905 with the shuttle replica Independence	jumbo and replica can be walked through
Joe Davies Heritage Airpark, Palmdale	NASA 911	open only some days a week
Udvar-Hazy Center, Washington	Orbiter Discovery	easy to combine with spotting at Dulles
Intrepid Museum, New York	Orbiter Enterprise	the space shuttle of 1977 and 1983

Discovery at the Udvar-Hazy Center combines wonderfully with a spotting afternoon; you will find tips at the spot Udvar-Hazy Center at Washington Dulles Airport. And if you are in Los Angeles anyway, the Los Angeles spotting guide helps with planning.

Context: giants with special missions

The SCA belongs in a line with other aircraft converted for unusual loads. The Soviet Union had the Antonov An-225 developed specifically for its Buran space shuttle. Airbus transports aircraft parts with special freighters such as the Beluga XL, and Boeing uses the 747 Dreamlifter for this. An overview of the very biggest is offered by the article The largest aircraft in the world.

For jumbo history as a whole, the SCA is a nice example of how versatile the type was: as a passenger aircraft, freighter, government aircraft and, of course, as a space shuttle taxi. The whole family story is told in the article The history of the Boeing 747; how to identify historic aircraft in old photos is covered under Spotting vintage aircraft in the sky.

Conclusion

The Shuttle Carrier Aircraft was never a production aircraft but a pair of highly specialized conversions. NASA 905 wrote space history with Enterprise’s landing tests and brought the Space Shuttle as far as Cologne Bonn and Paris in 1983. NASA 911 secured operations from 1990. Both have been retired since 2012 – and, unlike many jumbos of their generation, not scrapped but preserved in museums.