N905NA
N905NA, commonly called NASA 905, is the Boeing 747-123 that became NASA's first Shuttle Carrier Aircraft (SCA). Built as manufacturer serial number 20107 and Boeing line number 86, it entered service with American Airlines as N9668 in 1970. NASA acquired the aircraft in 1974, used it briefly for wake-vortex research and had Boeing convert it to carry Space Shuttle orbiters. It supported the 1977 Approach and Landing Tests with Enterprise, then ferried orbiters throughout the operational Shuttle programme and delivered three orbiters to museums in 2012. The aircraft is preserved at Space Center Houston beneath the high-fidelity Shuttle replica Independence.[1][2][3]
Identity and registrations
The airframe is a Boeing 747-123, the American Airlines customer version of the original Boeing 747 series. Its manufacturer serial number is 20107 and its Boeing production line number is 86. These are separate identifiers. The aircraft made its first flight on 15 October 1970 and was delivered to American Airlines as N9668 on 29 October.[4][5][6]
| Period | Registration | Operator or role |
| 1970–1974 | N9668 | American Airlines passenger aircraft |
| From 1974 | N905NA | NASA research aircraft and Shuttle Carrier Aircraft |
| From 2013 | N905NA displayed | Preserved at Space Center Houston |
The Federal Aviation Administration's current N-number record lists N905NA to NASA at Ellington Field, with serial number 20107, model 747-123, four Pratt & Whitney JT9D-series engines and a government registration in the experimental exhibition category. The registration record remains valid, but the FAA cautions that its public inquiry does not establish an aircraft's airworthiness. N905NA is a static museum exhibit, so a current registration entry must not be interpreted as evidence that it remains operational.[4][3]
American Airlines service and NASA acquisition
American Airlines operated N9668 as a passenger aircraft for fewer than four years. NASA bought the airframe on 18 July 1974 for approximately US$15.6 million. It had accumulated about 9,000 flight hours when acquired. NASA assigned the registration N905NA; the three digits also became the aircraft's widely used NASA tail number, 905.[2][5]
Before conversion, NASA used the 747 in a wake-vortex study. The aircraft flew behind a Lockheed C-5A to gather aerodynamic data on the effect of the larger aircraft's wake. This research phase explains why NASA acquired the aeroplane before the Shuttle Carrier Aircraft modification programme began.[1][2]
Conversion into a Shuttle Carrier Aircraft
NASA required an aircraft capable of transporting an orbiter between landing sites, servicing locations and launch facilities. Boeing began modifying N905NA on 2 August 1976. The work added three orbiter attachment structures, strengthened the fuselage, removed most of the airline cabin fittings aft of the forward passenger door and installed monitoring equipment for the combined vehicle.[2][1]
The orbiter disrupted airflow over the 747's normal tail. Boeing therefore added a small vertical fin at each end of the horizontal stabiliser, giving the SCA its distinctive triple-tail appearance. The original Pratt & Whitney JT9D-3A engines were upgraded during the conversion programme; later records identify the powerplants more generally as members of the JT9D series, and the FAA's present record does not specify a final suffix.[2][4]
For the 1977 crewed glide tests, the 747 received an emergency-escape system with a tunnel running from the flight deck to a hatch in the lower fuselage. Explosive devices intended to clear the exit area were fitted to the engine nacelles. The tunnel and associated provisions were removed after the Approach and Landing Test programme because they were unnecessary for routine ferry work.[2]
Boeing completed the principal conversion in December 1976. NASA 905 arrived at the Dryden Flight Research Center at Edwards Air Force Base on 14 January 1977. This SCA delivery date is distinct from both the airframe's first flight in 1970 and NASA's acquisition in 1974.[7][2]
Approach and Landing Tests
NASA 905 was central to the 1977 Approach and Landing Tests, which established that an unpowered orbiter could separate from the carrier, fly a landing approach and touch down safely. The test orbiter Enterprise was mounted above the 747's fuselage.[1][8]
The programme comprised eight captive flights and five free flights. Captive-inert flights carried an uncrewed Enterprise to assess the mated combination; captive-active flights added an orbiter crew and exercised its systems. During each free flight, NASA 905 climbed to the release point, Enterprise separated from the attachment struts and its crew glided to a runway at Edwards. The five releases between August and October 1977 tested configurations both with and without the orbiter's aerodynamic tail cone.[1][2]
These were release tests rather than orbital missions. Enterprise was an atmospheric test vehicle without engines or a complete orbital heat shield, and N905NA did not launch an orbiter into space.[2]
Operational Shuttle ferry service
After the test programme, NASA 905 became the transport link between dispersed Shuttle facilities. An orbiter that landed at Edwards or another diversion field could be lifted onto the SCA using a Mate-Demate Device, covered by an aerodynamic tail cone and ferried back to Kennedy Space Center. The combined aircraft normally required intermediate fuel stops because the orbiter greatly increased drag and fuel consumption.[1][2]
N905NA remained NASA's only Shuttle Carrier Aircraft until November 1990, when NASA 911 entered service. NASA's post-programme fact sheet credits NASA 905 with 70 of the 87 ferry missions during the operational Shuttle era, including 46 of 54 post-mission return ferries. A historical engineering record compiled before the final museum deliveries tabulated 56 ferry flights and 166 flight legs for 1979–2007. These totals use different units and date ranges: a ferry mission could contain several legs, and later museum transports are outside the earlier table.[1][2]
The aircraft also transported the non-orbital Enterprise to international and public events, including the 1983 Paris Air Show and the 1984 Louisiana World Exposition in New Orleans. The missions demonstrated the programme publicly but also rehearsed the specialised loading, route-planning and ground-support work needed for operational ferries.[1][2]
Flight characteristics and operations
Carrying an orbiter changed the 747's performance substantially. The orbiter was secured to forward and aft attachment structures above the fuselage, while its removable tail cone reduced aerodynamic drag around the exposed engine area. The SCA's additional tail fins restored directional stability lost in the orbiter's wake.[1][2]
The combined vehicle could not use normal airline-route assumptions. NASA assessed runway length, pavement strength, weather, obstacle clearance and suitable refuelling points for each ferry. Crews also managed restrictions arising from turbulence, icing and precipitation because the orbiter's thermal-protection system was exposed during flight.[2]
The aircraft retained a conventional 747 flight deck but no longer carried an airline passenger cabin. Its aft interior housed structural reinforcement and mission equipment, while the operational crew included pilots, flight engineers and support personnel appropriate to the ferry task.[1][2]
Other test and transport work
NASA used N905NA for work beyond the Shuttle ferry role. In 2010 and 2011 it carried Boeing's unmanned Phantom Ray demonstrator between St Louis and Edwards. The project used the same basic external-transport capability but mounted the smaller aircraft on a purpose-built fixture rather than the Shuttle orbiter attachment geometry.[2][9]
On 2 August 2011, NASA 905 and NASA 911 flew together for the first time. The formation flight over Edwards visually marked the two-aircraft SCA fleet near the end of the Shuttle programme.[2]
Retirement flights
After the final Shuttle mission in 2011, NASA used the SCAs to deliver retired orbiters to their permanent displays. N905NA carried Discovery to Washington Dulles International Airport, transported Enterprise onward to New York and delivered Endeavour to Los Angeles in 2012. Its September delivery of Endeavour was its last orbiter ferry.[1][10][9]
The aircraft departed NASA Dryden for the last time on 24 October 2012, flying unladen to Ellington Field in Houston. It then completed one final 90-minute pilot-proficiency flight in December 2012. The October departure was therefore its final flight from Dryden, not its last flight anywhere.[11][10]
NASA recorded 11,018 flight hours, 6,335 take-offs and landings, and 42 years of flying at retirement. Space Center Houston publishes 11,017 flight hours, a difference of one hour that most likely reflects rounding or a different cut-off. The official totals should be quoted with their source rather than combined into an apparently exact single figure.[1][3]
Preservation at Space Center Houston
NASA formally handed N905NA to Space Center Houston at Ellington Field on 22 August 2013. Because the complete 747 could not be moved through Houston streets, crews dismantled it into seven principal loads. The operation included removing the wings and tail and cutting the main landing-gear beam before a road journey to the visitor centre. The aircraft was then reassembled as the foundation of Independence Plaza.[12][3]
A high-fidelity Shuttle replica renamed Independence is mounted on the SCA. It is not one of NASA's flown orbiters and should not be confused with Enterprise, Discovery or Endeavour, all of which N905NA carried. Independence Plaza opened in January 2016.[3][12]
Visitors can enter both the 747 and the replica. Exhibits inside the SCA interpret the Shuttle programme, ferry missions and aircraft modifications. Space Center Houston describes it as the only displayed Shuttle-on-carrier combination in which the public can enter both vehicles.[3]
Mission-count definitions
Published totals for NASA 905 describe different activities and are not interchangeable:
NASA's SCA fact sheet records 70 of 87 operational-era ferry missions, including 46 of 54 post-mission return ferries.[1]
The Historic American Engineering Record lists 56 ferry flights divided into 166 legs for 1979–2007.[2]
Space Center Houston says the aircraft carried Shuttle vehicles 223 times, a broader exhibit-oriented count that includes Enterprise and operational orbiters.[3]
NASA's 2012 ferry summary also counts the five 1977 free-flight releases and two Phantom Ray transports when presenting its wider total of piggyback missions.[9]
The figures answer different questions. A multi-stop ferry can be one mission but several flight legs, while a captive test, free-flight release or non-Shuttle payload may be included in one published summary and excluded from another.
Timeline
| Date | Event |
| 15 October 1970 | First flight as Boeing 747-123 N9668 |
| 29 October 1970 | Delivered to American Airlines |
| 18 July 1974 | Acquired by NASA and assigned N905NA |
| 1974–1975 | Used for NASA wake-vortex research |
| 2 August 1976 | Boeing began Shuttle Carrier Aircraft modification |
| December 1976 | Principal SCA conversion completed |
| 14 January 1977 | Delivered to NASA Dryden in SCA configuration |
| February–October 1977 | Completed captive and free-flight Approach and Landing Tests |
| 1979 | Began operational Shuttle ferry work |
| 1983 | Carried Enterprise to the Paris Air Show |
| November 1990 | NASA 911 joined the Shuttle Carrier Aircraft fleet |
| 2010–2011 | Transported the Phantom Ray demonstrator |
| 2 August 2011 | First formation flight with NASA 911 |
| April 2012 | Delivered Discovery for preservation and moved Enterprise to New York |
| September 2012 | Delivered Endeavour to Los Angeles on its final orbiter ferry |
| 24 October 2012 | Final departure from NASA Dryden, bound for Ellington Field |
| December 2012 | Final aircraft flight, a 90-minute proficiency sortie |
| 22 August 2013 | Formally handed over to Space Center Houston |
| January 2016 | Independence Plaza opened to the public |
Data-quality notes
N905NA is NASA 905, the first Shuttle Carrier Aircraft; it is not N747NA, the 747SP used for the SOFIA airborne observatory.
Manufacturer serial number 20107, Boeing line number 86 and NASA tail number 905 are separate identifiers.
The original first flight, NASA acquisition and post-conversion delivery occurred in 1970, 1974 and 1977 respectively.
N9668 was the American Airlines registration; N905NA was assigned after NASA acquired the aircraft.
The final orbiter ferry, final departure from Dryden and final aircraft flight were three separate events in September, October and December 2012.
The aircraft remains in the FAA registry but is a static museum exhibit; registry validity does not establish airworthiness.
Published counts of missions, flights, legs and carried vehicles use different definitions and time periods.
The vehicle mounted on N905NA today is the display replica Independence, not a flown Space Shuttle orbiter.
Related pages
Sources
Shuttle Carrier Aircraft fact sheet — NASA Armstrong Flight Research Center
NASA Shuttle Carrier Aircraft historical narrative — Historic American Engineering Record, National Park Service and NASA
January 14, 1977 — NASA
N905NA aircraft inquiry — Federal Aviation Administration, accessed 29 August 2026
Shuttle Carrier Aircraft 905 final flight from NASA Dryden — NASA
Independence Plaza — Space Center Houston
NASA 905's handover — Space Center Houston
NASA 905 celebrates its 50th birthday — Space Center Houston
Shuttle ferry numbers — NASA
N905NA production record — JetPhotos, accessed 29 August 2026
Image source and rights: Shuttle Carrier Aircraft and Endeavour — Carla Thomas, NASA/DFRC, public domain, via Wikimedia Commons
