Daily Archives: December 20, 2020

20 December 2004

20th Fighter Squadron Luftwaffe McDonnell Douglas F-4F-54-MC Phantom 72-1150, with another F-4F over the skies of Holloman AFB, New Mexico. (U.S. Air Force)
20th Fighter Squadron McDonnell Douglas F-4F-54-MC Phantom 72-1150, with another F-4F banking away, over the skies of  New Mexico. (U.S. Air Force)

20 December 2004: The 20th Fighter Squadron, 49th Fighter Wing, Holloman Air Force Base, New Mexico, the last operational squadron in the United States Air Force flying the McDonnell Douglas F-4 Phantom II, was inactivated. The squadron’s F-4F fighters were sent to The Boneyard at Davis-Monthan Air Force Base, Tucson, Arizona.

Row after row of F-4 Phantom II fighters in storage at Davis-Monthan AFB.
Row after row of F-4 Phantom II fighters in storage at Davis-Monthan AFB, near Tucson, Arizona.

© 2015, Bryan R. Swopes

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20 December 1969

Senior Lieutenant Nguyễn Văn Cốc in the cockpit of a MiG 21. (From the collection of CMSGT Bob Laymon, USAF)

20 December 1969: Senior Lieutenant Nguyễn Văn Cốc, of the 921st Fighter Regiment, Vietnam Peoples’ Air Force, flying a Mikoyan-Gurevich Mig 21PFL supersonic interceptor, shot down his final enemy aircraft of the Vietnam War, a U.S. Air Force AQM-34L  reconnaissance drone (Ryan Aeronautical Company Model 147SC, code named BUFFALO HUNTER).

A U.S. Air Force Ryan AQM-34L Buffalo Hunter of the 556th Reconnaissance Squadron, based at Bien Hoa Air Base, circa 1969. This drone flew 68 missions before being shot down over Hanoi. (U.S. Air Force)

Nguyễn Văn Cốc entered the Không quân Nhân dân Việt Nam (Vietnamese People’s Air Force) in 1961. He spent four years in the Soviet Union training as a fighter pilot, and was qualified on both the Mikoyan-Gurevich MiG 17 and MiG 21.

Nguyễn was credited by the VPAF with nine aerial combat victories. Seven of these were also confirmed by the United States. Between 30 April 1967 and 20 December 1969, he shot down a Convair F-102A Delta Dart, three Republic F-105D Thunderchiefs, one F-105F Thunderchief, a McDonnell F-4B Phantom II, two F-4D Phantom IIs, and the BUFFALO HUNTER.

Senior Lieutenant Nguyễn Văn Cốc, at right, with two other pilots. A Mikoyan-Gurevich MiG 21PF is in the background. (VPAF)

All of Nguyễn’s victories were scored while flying the MiG 21PFL, with R-3S infrared-homing air-to-air missiles.

These MiG 21s are assigned to the 921st Fighter Regiment. The closest, “Red 4326,” is one of the interceptors flown by Nguyễn Văn Cốc. The 13 “kill marks” on its nose represent enemy aircraft shot down by Nguyễn and other pilots who flew the airplane. This airplane is on display at the Hanoi Air Defense Museum (Bảo tàng Phòng không-Không quân). (VPAF)

The R-3S (also known as the K-13, and identified as “AA-2A Atoll” by NATO forces) was reverse-engineered by the Turopov Design Bureau, Tushino, Russia, from a Raytheon AIM-9B Sidewinder which had been captured by the People’s Republic of China during the 1958 Taiwan Straits Crisis. Fired by a Republic of China Air Force F-86 Sabre, the missile hit a People’s Liberation Army Air Force MiG 17, but its warhead did not detonate. The PLAAF turned the Sidewinder over to the Soviet Union.

Lieutenant General Nguyễn remained in the VPAF until retiring in 2002 with the rank of chief inspector. He is the highest-scoring fighter pilot of the Vietnam War.

Captain Nguyễn Văn Cốc is congratulated by Hồ Chí Minh, President of the Democratic Republic of Vietnam.

The BUFFALO HUNTER was approximately 26 feet (7.9 meters) long with a wing span of 13 feet (4.0 meters). It weighed 3,067 pounds (1,391 kilograms).

The drone was powered by a single Continental J69 turbojet engine, rated at 1,920 pounds of thrust (8.54 kilonewtons).

BUFFLO HUNTERS had a  cruising speed of 500–540 knots (575–621 miles per hour/926-1,000 kilometers per hour), but could reach 590 knots (679 miles per hour/1,093 kilometers per hour) “on the deck.” It had a maximum range of 650 nautical miles (748 statute miles/1,204 kilometers).

The drone was equipped with a Fairchild 415Y reconnaissance camera. It carried 1,800 feet (549 meters) of 70-millimeter film.

BUFFALO HUNTERs were launched by Lockheed DC-130 drone carriers, modified from C130 A or -E Hercules transports. Most carried two drones on underwing pylons, but two of the DC-130s could carry four.

A Lockheed DC-130 carrying two BUFFALO HUNTER reconnaissance drones. (U.S. Air Force)

© 2018, Bryan R. Swopes

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North American Aviation, Inc., X-15A Hypersonic Research Rocketplane

Rollout AFFTC History Office
North American Aviation, Inc., X-15A-1, 56-6670, at Los Angeles Division, October 1958. (Air Force Flight Test Center History Office)

20 December 1968: After 199 flights, the National Aeronautics and Space Administration cancelled the X-15 Hypersonic Research Program. A 200th X-15 flight had been scheduled, but after several delays, the decision was made to end the program. (The last actual flight attempt was 12 December 1968, but snow at several of the dry lakes used as emergency landing areas resulted in the flight being cancelled.)

The X-15A rocketplane was designed and built for the U.S. Air Force and the National Advisory Committee for Aeronautics (NACA, the predecessor of NASA) by North American Aviation, Inc., to investigate the effects of hypersonic flight (Mach 5+). Design work started in 1955 and a mock-up had been completed after just 12 months. The three X-15s were built at North American’s Los Angeles Division, at the southeast corner of Los Angeles International Airport (LAX), on the shoreline of southern California.

The first flight took place 8 June 1959 with former NACA test pilot Albert Scott Crossfield in the cockpit of the Number 1 ship, 56-6670.

Scott Crossfield prepares for a flight in the North American Aviation X-15A.

While earlier rocketplanes, the Bell X-1 series, the the Douglas D-558-II, and the Bell X-2, were airplanes powered by rocket engines, the X-15 was a quantum leap in technology. It was a spacecraft.

Like the other rocketplanes, the X-15 was designed to be carried aloft by a “mothership,” rather than to takeoff and climb to the test altitude under its own power. The carrier aircraft was originally to be a Convair B-36 intercontinental bomber but this was soon changed to a Boeing B-52 Stratofortress. Two B-52s were modified to carry the X-15: NB-52A 52-003, The High and Mighty One, and NB-52B 52-008, Balls 8.

From 8 June 1959 to 24 October 1968, the three X-15s were flown by twelve test pilots, three of whom would qualify as astronauts in the X-15. Two would go on to the Apollo Program, and one, Neil Alden Armstrong, would be the first human to set foot on the surface of the Moon, 20 July 1969. Joe Engle would fly the space shuttle. Four of the test pilots, Petersen, White, Rushworth, and Knight, flew in combat during the Vietnam War, with Bob White being awarded the Air Force Cross. Petersen, Rushworth and White reached flag rank.

One pilot, John B. (“Jack”) McKay, was seriously injured during an emergency landing at Mud Lake, Nevada, 9 November 1962. Another, Michael James Adams, was killed when the Number 3 ship, 56-6672, went into a hypersonic spin and broke up on the program’s 191st flight, 15 November 1967.

North American Aviation, Inc. X-15A 56-6670 on Rogers Dry Lake, Edwards Air Force Base, California. (NASA)
North American Aviation, Inc., X-15A-1 56-6670 on Rogers Dry Lake, Edwards Air Force Base, California. (NASA Image E-5251)

Flown by a single pilot/astronaut, the X-15 is a mid-wing monoplane with dorsal and ventral fin/rudders and stabilators. The wing had no dihdral, while the stabilators had a pronounced -15° anhedral. The short wings have an area of 200 square feet (18.58 square meters) and a maximum thickness of just 5%. The leading edges are swept to 25.64°. There are two small flaps but no ailerons. The entire vertical fin/rudder pivots for yaw control.

Above 100,000 feet (30,840 meters) altitude, conventional aircraft flight control surfaces are ineffective. The X-15 is equipped with a system of reaction control jets for pitch, roll and yaw control. Hydrogen peroxide was passed through a catalyst to produce steam, which supplied the control thrusters.

The forward landing gear consists of a retractable oleo strut with steerable dual wheels and there are two strut/skids at the rear of the fuselage. The gear is retracted after the X-15 is mounted on the NB-52 and is extended for landing by its own weight.

 North American Aviation X-15A 56-6672 touches down on Rogers Dry Lake. (NASA)
North American Aviation, Inc., X-15A-3 56-6672 just before touch down on Rogers Dry Lake. (NASA Image E-7469)

The rocketplane’s cockpit featured both a conventional control stick as well as side-controllers. It was pressurized with nitrogen gas to prevent fires. The pilot wore an MC-2 full-pressure suit manufactured by the David Clark Company of Worcester, Massachusetts, with an MA-3 helmet. The suit was pressurized below the neck seal with nitrogen, while the helmet was supplied with 100% oxygen. This pressure suit was later changed to the Air Force-standardized A/P22S.

X-15A cockpit with original Lear Siegler instrument panel. (NASA)
X-15 cockpit with original Lear Siegler instrument panel. (NASA image E63-9834)

The X-15 is 50.75 feet (15.469 meters) long with a wing span of 22.36 feet (6.815 meters). The height—the distance between the tips of the dorsal and ventral fins—is 13.5 feet (4.115 meters). The stabilator span is 18.08 feet (5.511 meters). The fuselage is 4.67 feet (1.423 meters) deep and has a maximum width of 7.33 feet (2.234 meters).

Since the X-15 was built of steel rather than light-weight aluminum, as are most aircraft, it is a heavy machine, weighing approximately 14,600 pounds (6,623 kilograms) empty and 34,000 pounds (15,422 kilograms) when loaded with a pilot and propellants. The X-15s carried as much as 1,300 pounds (590 kilograms) of research instrumentation, and the equipment varied from flight to flight. The minimum flight weight (for high-speed missions): 31,292 pounds (14,194 kilograms) The maximum weight was 52,117 pounds (23,640 kilograms) at drop (modified X-15A-2 with external propellant tanks).

Initial flights were flown with a 5 foot, 11 inch (1.803 meters)-long air data boom at the nose, but this would later be replaced by the “ball nose” air sensor system. The data boom contained a standard pitot-static system along with angle-of-attack and sideslip vanes. The boom and ball nose were interchangeable.

Neil Armstrong with the first North American Aviation X-15A, 56-6670, on Rogers Dry Lake after a flight, 1960. His hand is resting on the rocketplane's ball nose sensor. (NASA)
NASA Research Test Pilot Neil A. Armstrong with the first North American Aviation X-15A, 56-6670, on Rogers Dry Lake after a flight, 1960. His right hand is resting on the rocketplane’s ball nose sensor. (NASA Image E60-6286)

The X-15s were built primarily of a nickel/chromium/iron alloy named Inconel X, along with corrosion-resistant steel, titanium and aluminum. Inconel X is both very hard and also able to maintain its strength at the very high temperatures the X-15s were subjected to by aerodynamic heating. It was extremely difficult to machine and special fabrication techniques had to be developed.

Delays in the production of the planned Reaction Motors XLR99 rocket engine forced engineers to adapt two vertically-stacked Reaction Motors XLR11-RM-13 four-chamber rocket engines to the X-15 for early flights. This was a well-known engine which was used on the previous rocketplanes. The XLR11 burned a mixture of ethyl alcohol and water with liquid oxygen. Each of the engines’ chambers could be ignited individually. Each engine was rated at 11,800 pounds of thrust (58.49 kilonewtons) at Sea Level.

Two Reaction Motors Division XLR11-RM-5 four-chamber rocket engines installed on an X-15. (NASA)
Two Reaction Motors Division XLR11-RM-13 four-chamber rocket engines installed on an X-15. The speed brakes of the ventral fin are shown in the open position. (NASA)

The Reaction Motors XLR99-RM-1 rocket engine was throttleable by the pilot from 28,500 to 60,000 pounds of thrust (126.77–266.89 kilonewtons). The engine was rated at 50,000 pounds of thrust (222.41 kilonewtons) at Sea Level; 57,000 pounds (253.55 kilonewtons) at 45,000 feet (13,716 meters), the typical drop altitude; and 57,850 pounds (257.33 kilonewtons) of thrust at 100,000 feet (30,480 meters). Individual engines varied slightly. A few produced as much as 61,000 pounds of thrust (271.34 kilonewtons).

The XLR99 burned anhydrous ammonia and liquid oxygen. The flame temperature was approximately 5,000 °F. (2,760 °C.) The engine was cooled with circulating liquid oxygen. To protect the exhaust nozzle, it was flame-sprayed with ceramic coating of zirconium dioxide. The engine is 6 feet, 10 inches (2.083 meters) long and 3 feet, 3.3 inches (0.998 meters) in diameter. It weighs 910 pounds (413 kilograms). The Time Between Overhauls (TBO) is 1 hour of operation, or 100 starts.

Thiokol Reaction Motors Division XLR-RM-1 rocket engine. (U.S. Air Force)
Thiokol Corporation Reaction Motors Division XLR99-RM-1 rocket engine. (U.S. Air Force)

The XLR99 proved to be very reliable. 169 X-15 flights were made using the XLR99. 165 of these had successful engine operation. It started on the first attempt 159 times.

The highest speed achieved during the program was with the modified number two ship, X-15A-2 56-6671, flown by Pete Knight to Mach 6.70 (6,620 feet per second/4,520 miles per hour/7,264 kilometers per hour) at 102,700 feet (31,303 meters). On this flight, the rocketplane exceeded its maximum design speed of 6,600 feet per second (2,012 meters per second).

The maximum altitude was reached by Joe Walker, 22 August 1963, when he flew 56-6672 to 354,200 feet (107,960 meters).

The longest flight was flown by Neil Armstrong, 20 April 1962, with a duration of 12 minutes, 28.7 seconds.

North American Aviation X-15A-1 56-6670 is on display at the Smithsonian Institution National Air and Space Museum. X-15A-2 56-6671 is at the National Museum of the United States Air Force.

A North American Aviation F-100 Super Sabre chase plane follows NB-52A 52-003 prior to launch of an X-15. (NASA)
A North American Aviation F-100 Super Sabre chase plane follows NB-52A 52-003 prior to launch of an X-15. (NASA)

Recommended reading:

Always Another Dawn: The Story of a Rocket Test Pilot, by A. Scott Crossfield and Clay Blair, Jr., The World Publishing Company, Cleveland and New York, 1960

At The Edge Of Space, by Milton O. Thompson, Smithsonian Institution Press, 1992

X-15 Diary: The Story of America’s First Spaceship, by Richard Tregaskis, E.F. Dutton & Company,  New York, 1961; University of Nebraska Press, 2004

X-15: Exploring the Frontiers of Flight, by David R. Jenkins, National Aeronautics and Space Administration http://www.nasa.gov/pdf/470842main_X_15_Frontier_of_Flight.pdf

The X-15 Rocket Plane: Flying the First Wings into Space, by Michelle Evans, University of Nebraska Press, Lincoln and London, 2013

Screen Shot 2016-06-07 at 21.18.14
North American Aviation, Inc., X-15A-2 56-6671 accelerates after igniting its Reaction Motors XLR99-RM-1 rocket engine (NASA)

© 2018, Bryan R. Swopes

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20 December 1962

Milton O. Thompson with a Lockheed JF-104A Starfighter at Edwards Air Force Base, 20 December 1962. (NASA)

20 December 1962: Milton Orville Thompson, a NASA test pilot assigned to the X-15 hypersonic research program, was conducting a weather check along the X-15’s planned flight path from Mud Lake, Nevada, to Edwards Air Force Base in California, scheduled for later in the day. Thompson was flying a Lockheed F-104A-10-LO Starfighter, Air Force serial number 56-749, call sign NASA 749.

NASA 749, a Lockheed JF-104A Starfighter, 56-749, with an ALSOR sounding rocket on a centerline mount, at Edwards Air Force Base. Right front quarter view. (NASA)
NASA 749, a Lockheed JF-104A Starfighter, 56-749, with an ALSOR sounding rocket on a centerline mount, at Edwards Air Force Base. (NASA)

In his autobiography, At the Edge of Space, Thompson described the day:

“The morning of my weather flight was a classic desert winter morning. It was cold, freezing in fact, but  the sky was crystal clear and there was not a hint of a breeze—a beautiful morning for a flight.”

Completing the weather reconnaissance mission, and with fuel remaining in the Starfighter’s tanks, Milt Thompson began practicing simulated X-15 approaches to the dry lake bed.

X-15 pilots used the F-104 to practice landing approaches. The two aircraft were almost the same size, and with speed brakes extended and the flaps lowered, an F-104 had almost the same lift-over-drag ratio as the X-15 in subsonic flight. Thompson’s first approach went fine and he climbed back to altitude for another practice landing.

Lockheed F-104A-10-LO Starfighter 56-749 (NASA 749) carrying a sounding rocket on a centerline mount. (NASA)
Lockheed F-104A-10-LO Starfighter 56-749 (NASA 749) carrying an ALSOR sounding rocket on a centerline mount. (NASA)

When Milt Thompson extended the F-104’s flaps for the second simulated X-15 approach, he was at the “high key”— over Rogers Dry Lake at 35,000 feet (10,668 meters) — and supersonic. As he extended the speed brakes and lowered the flaps, NASA 749 began to roll to the left. With full aileron and rudder input, he was unable to stop the roll. Adding throttle to increase the airplane’s airspeed, he was just able to stop the roll with full opposite aileron.

Thompson found that he could maintain control as long as he stayed above 350 knots (402 miles per hour/648 kilometers per hour) but that was far too high a speed to land the airplane. He experimented with different control positions and throttle settings. He recycled the brake and flaps switches to see if he could get a response, but there was no change. He could see that the leading edge flaps were up and locked, but was unable to determine the position of the trailing edge flaps. He came to the conclusion that the trailing edge flaps were lowered to different angles.

Thompson called Joe Walker, NASA’s chief test pilot, on the radio and explained the situation:

     I told him the symptoms of my problem and he decided that I had a split trailing edge flap situation with one down and one up.

     He suggested I recycle the flap lever to the up position to attempt to get both flaps up and locked. I had already tried that, but I gave it another try. Joe asked if I had cycled the flap lever from the up to the takeoff position and then back again. I said no. I had only cycled the flap lever from the up position to a position just below it and then back to the up position. Joe suggested we try it his way. I moved the flap lever from the up position all the way to the takeoff position and then back to the up position. As soon as I moved the lever to the takeoff position, I knew I had done the wrong thing.

     The airplane started rolling again, but this time I could not stop it. The roll rate quickly built up to the point that I was almost doing snap rolls. Simultaneously, the nose of the airplane started down. I was soon doing vertical rolls as the airspeed began rapidly increasing. I knew I had to get out quick because I did not want to eject supersonic and I was already passing through 0.9 Mach. I let go of the stick and reached for the ejection handle. I bent my head forward to see the handle and then I pulled it. Things were a blur from that point on.

At the Edge of Space: The X-15 Flight Program, by Milton O. Thompson, Smithsonian Institution Press, Washington and London, 1992. Chapter 5 at Pages 119–120.

Impact crater caused by crash of Milt Thompson's Lockheed F-104 Starfighter, 20 Decemver 1962. NASA)
Impact crater caused by the crash and explosion of Milt Thompson’s Lockheed JF-104A Starfighter, 20 December 1962. (NASA)

As Thompson descended by parachute he watched the F-104 hit the ground and explode in the bombing range on the east side of Rogers Dry Lake. He wrote, “It was only 7:30 a.m. and still a beautiful morning.”

© 2018, Bryan R. Swopes

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20 December 1957

Boeing 707-121 N708PA, photographed during its second flight. (Boeing via Space.com)
Boeing 707-121 N708PA, photographed during its second flight on the afternoon of 20 December 1957. (Boeing)
Boeing 707-121 N708PA makes its first takeoff at 12:30 p.m., on a rainy afternoon, 20 December 1957. (Unattributed)
Boeing 707-121 N708PA makes its first takeoff at 12:30 p.m. on a rainy afternoon, 20 December 1957. (Boeing)

20 December 1957: The first production Boeing 707 jet-powered commercial airliner, N708PA, made its first flight at Renton, Washington. Alvin M. “Tex” Johnston, Boeing’s Chief of Flight Test, was in command, with co-pilot James R. Gannet and flight engineer Tom Layne. Takeoff was at 12:30 p.m., PST. Poor weather limited the first flight to just 7 minutes. The new airliner landed at Boeing Field. Later that day, a second flight was made, this time with a duration of 1 hour, 11 minutes.

N708PA (Serial Number 17586, Line Number 1) was a Model 707-121. The new airliner had been sold to Pan American World Airways, the launch customer, as part of an order for twenty 707s in October 1955.

Boeing test pilot Alvin M. "Tex" Johnston in the cockpit of of the 367–80. (LIFE)
Boeing’s Chief of Flight Test, Alvin M. “Tex” Johnston, in the cockpit of of the 367–80, “Dash Eighty,” 1954. (LIFE Magazine via Jet Pilot Overseas)

The Boeing Model 707 was developed from the earlier Model 367–80, the “Dash Eighty,” prototype for an air-refueling tanker which would become the KC-135A Stratotanker. The 707 was a four-engine jet transport with swept wings and tail surfaces. The leading edge of the wings were swept at a 35° angle.

N708PA was initially used for flight testing by Boeing. Once this was completed, it was prepared for commercial service and delivered to Pan American at San Francisco International Airport (SFO), 30 November 1958. Pan Am named the new airliner Clipper Constitution.

Boeing 707-121 708PA under maintenance at Renton, Washington. (Boeing)
Boeing 707-121 N708PA under maintenance at Renton, Washington. (Boeing)

In February 1965, the airliner was upgraded to 707-121B standards, which replaced the original turbojet engines with quieter, more efficient Pratt & Whitney JT3D-1 turbofan engines which produced 17,000 pounds of thrust. The wing inboard leading edges were modified to the design of the Model 720 and there was a longer horizontal tail plane.

Clipper Constitution flew for Pan Am for nearly seven years, until 17 September 1965 when it crashed into Chances Peak, a 3,002 foot (915 meters) volcano on the Caribbean island of Montserrat. The point impact  was 242 feet (74 meters) below the summit. All aboard, a crew of 9 and 21 passengers, were killed.

Boeing 707-121 N708PA, with both Boeing and Pan American corporate markings. (Unattributed)
Boeing 707-121 N708PA, with both Boeing and Pan American corporate markings. (Unattributed)

The Boeing Model 707-121 was a four-engine jet transport with swept wings and tail surfaces. The leading edge of the wings were swept at a 35° angle. The airliner had a flight crew of four: pilot, co-pilot, navigator and flight engineer.

The 707-121 was 145 feet, 1 inch (44.221 meters) long with a wing span of 130 feet, 10 inches (39.878 meters). The top of the vertical fin stood 42 feet, 5 inches (12.929 meters) high. The 707 pre-dated the ”wide-body” airliners, having a fuselage width of 12 feet, 4 inches (3.759 meters). The airliner’s empty weight is 122,533 pounds (55,580 kilograms). Maximum take off weight is 257,000 pounds (116,573 kilograms).

The first versions were powered by four Pratt & Whitney Turbo Wasp JT3C-6 turbojet engines, producing 11,200 pounds of thrust (49,820 kilonewtons), and 13,500 pounds (60.051 kilonewtons) with water injection. This engine was a civil variant of the military J57 series. It was a two-spool axial-flow turbojet engine with a 16-stage compressor and 2 stage turbine. The JT3C-6 was 11 feet, 6.6 inches (3.520 meters) long, 3 feet, 2.9 inches (0.988 meters) in diameter, and weighed 4,235 pounds (1,921 kilograms).

At MTOW, the 707 required 11,000 feet (3,352.8 meters) of runway to take off.

The 707-121 had a maximum speed of 540 knots (1,000 kilometers per hour). It’s range was 2,800 nautical miles (5,186 kilometers).

The Boeing 707 was in production from 1958 to 1979. 1,010 were built. Production of 707 airframes continued at Renton until the final one was completed in April 1991. As of 2011, 43 707s were still in service.

Boeing 707-121 N708PA retracts its landing gear after taking off at Seattle Tacoma Airport. (Unattributed)
Boeing 707-121 N708PA landing at Seattle Tacoma Airport. (Unattributed)

© 2016, Bryan R. Swopes

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