Tag Archives: Aircraft Accident

19 February 1985

China Airlines' Boeing 747SP, N45522V. Thi saircraft few as Dynasty 006, 18 February 1985. (Andrew Hunt)
China Airlines’ Boeing 747SP, N4522V. This aircraft few as Dynasty 006, 18 February 1985. (Andrew Hunt)

19 February 1985: At 10:16 a.m., Pacific Standard Time, while enroute from Taipei, Republic of Taiwan, to Los Angeles, California, China Airlines’ Flight 006 (call sign “Dynasty Six”), a Boeing 747SP-09, FAA registration N4522V, was cruising at 41,000 feet (12,497 meters), 300 nautical miles (556 kilometers) northwest of San Francisco, California. It had a crew of 23 with 251 passengers. The airliner had a flight crew of five under command of Captain Min-Yuan Ho, with a co-pilot and flight engineer, as well as a relief captain and flight engineer, due to the length of the trans-Pacific flight.

Captain Min-Yuan Ho, describing the incident to reporters at San Francisco Airport, 19 February 1985.
Captain Min-Yuan Ho, describing the incident to reporters at San Francisco Airport, 19 February 1985.

The Number 4 engine, the outboard engine on the airplane’s right wing, a Pratt & Whitney JT9D-7A turbofan, refused to respond with the other engines as the throttles were advanced, and it “hung” and remained at a low power level. It did not flame out, as the crew believed. The crew attempted restart procedures, however they did so incorrectly.

The airliner’s autopilot was engaged and the aircraft began to yaw and bank because of the asymmetric thrust. The copilot, First Officer Ju Yu Chang, used full opposite aileron to stop the roll, but neither pilot or copilot applied any rudder inputs to correct the yaw. (It was later determined that they believed, incorrectly, that the autopilot controlled rudder position.)

The airplane departed controlled flight, rolled over and dived. It lost 30,000 feet (9,144 meters) of altitude before the crew was able to recover, however the airplane was severely damaged, with bent wings, a damaged left aileron, lost parts of its elevators and horizontal stabilizers and damaged landing gear doors. It had experienced acceleration forces as high as 4.8 Gs as it descended through 30,552 feet (9,312 meters) and a peak 5.1 Gs at 19,083 feet (5,816 meters).

This illustration, based on the NTSB accident investigation, shows the various attitudes of China Airlines Flight 006 as it descended out of control, 19 February 1985. (Wikipedia)
This illustration, based on the NTSB accident investigation, shows the various attitudes of China Airlines Flight 006 as it descended out of control, 19 February 1985. (Wikipedia)

Of the 287 persons on board, 24 were injured. Two were seriously hurt and the flight diverted to San Francisco. The 747SP was substantially damaged. It was nearly two years before repairs completed.

The National Transportation Safety Board investigation made the following findings:

3.1 Findings

1. The flightcrew was properly certificated and qualified.

2. The changing airspeeds encountered by Flight 006 and the resultant compensating throttle adjustments were caused by wind speed variations.

3. The No. 4 engine did not flame out, but “hung” at about 1.0 EPR.

4. During his attempt to recover the No. 4 engine, the flight engineer did not close the bleed air valve switch before advancing the No. 4 throttle.

5. The other three engines did not lose thrust nor did they flame out.

6. The captain did not disengage the autopilot in a timely manner after thrust was lost on the No. 4 engine. The autopilot effectively masked the approaching onset of the loss of control of the airplane.

7. The captain was distracted from his flight monitoring duties by his participation with the flight engineer in the evaluation of the No. 4 engine’s malfunction.

8. With the exception of the loss of thrust on the No. 4 engine, no other airplane malfunction affected the performance of the airplane; the loss of thrust on the No. 4 engine did not contribute to the accident.

9. The captain was also distracted by his attempts to arrest the airplane’s decreasing airspeed, and this also contributed to his failure to detect the airplane’s increasing bank angle.

10. The lateral control deflections required to maintain level flight under conditions of thrust asymmetry and decreasing airspeed exceeded the limits of the autopilot’s lateral control authority, causing the airplane to roll and yaw to the right. The captain lost control of the airplane when, after disengaging the autopilot, he failed to make the proper flight control corrections to recover the airplane.

11. The damage to the airplane was a result of the acceleration forces and high airspeeds that occurred during the upset and recovery maneuvers.

3.2 Probable Cause

The National Transportation Safety Board determines that the probable cause of this accident was the captain’s preoccupation with an inflight malfunction and his failure to monitor properly the airplane’s flight instruments which resulted in his losing control of the airplane.

Contributing to the accident was the captain’s over-reliance on the autopilot after the loss of thrust on the No. 4 engine.

The captain had not slept during his previous rest period and his tiredness was considered a factor in this incident.

Damage to the tail surfaces of Boeing 747SP N4522V.
Damage to the tail surfaces of Boeing 747SP N4522V.

The Boeing 747SP (“Special Performance”) is a very long range variant of the 747-100 series airliners. It has a shorter fuselage and larger tail surface than the standard model. The weight savings allows it to carry more fuel for longer flights, and it is also faster. Boeing built 45 747SPs.

The 747SP is 184 feet, 9 inches (56.312 meters) long, with a wingspan of 195 feet, 8 inches (59.639 meters). It has an overall height of 65 feet, 10 inches (20.066 meters). It has a maximum takeoff weight of 670,000 pounds.

The airliner has a cruising speed of 0.88 Mach (616 miles per hour, or 991 kilometers per hour) and a maximum speed of 0.92 Mach (680 knots, 1,094 kilometers per hour). The service ceiling is 45,100 feet (13,746 meters) and the range is 7,650 miles (12,311 kilometers), carrying 276 passengers and baggage. The fuel capacity is 47,210 gallons. (178,709 liters).

Damaged horizontal stabilizer and elevators of Boeing 747SP-09 N4522V (NTSB)

The FAA registration of N4522V expired 31 December 2016. It was last registered to Global Peace Initiative Inc., Huffman, Texas. The airplane is stored at Tijuana International Airport (TIJ), just south of the U.S./Mexico border.

© 2017, Bryan R. Swopes

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18 February 1943, 12:26 p.m., Pacific War Time

The second prototype Boeing XB-29 Superfortress, 41-0003, takes off from Boeing Field, 12:09 p.m., 18 February 1943. (Boeing)
The second prototype Boeing XB-29 Superfortress, 41-0003, takes off from Boeing Field, 12:09 p.m., 18 February 1943. (Boeing)

18 February 1943: At 12:09 p.m., Boeing Aircraft Company Chief Test Pilot Edmund Turney (“Eddie”) Allen took off from Boeing Field, Seattle, Washington, in the Number 2 prototype XB-29 Superfortress long-range heavy bomber, serial number 41-0003. Allen’s co-pilot was engineering test pilot Robert R. Dansfield. The rest of the XB-29 flight crew were Charles Edmund Blaine, flight test engineer; Fritz Mohn, senior inspector; Vincent W. North, aerodynamicist; Harry William Ralston, radio operator; Barclay J. Henshaw, flight test analyst; Thomas R. Lankford, engineer; Robert Willis Maxfield, flight test engineer; Raymond Louis Basel, flight test engineer; Edward I. Wersebe, flight test engineer.

Edmund T. ("Eddie") Allen. (San Diego Air and Space Museum Archive)
Edmund Turney Allen. (San Diego Air and Space Museum Archive)

41-0003 had first flown on 30 December 1942, piloted by Allen. During this flight, the prototype bomber suffered a major engine fire and Eddie Allen’s performance in returning the airplane to the airport later earned him the U.S. Army’s Air Medal, awarded on the specific orders of President Harry S. Truman.

Problems with the XB-29s’ Wright R-3350-13 engines had caused major delays in the B-29 testing program. The Number 2 aircraft had its engines replaced with those from the first XB-29, 41-0002. By 18 February, 41-0003 had made only eight flights, with a total flight time of 7 hours, 27 minutes.

The ninth test flight of 41-0003 was planned to test the climb performance to 25,000 feet (7,620 meters) and to collect engine cooling data.

At 12:17 p.m., 41-0003 was climbing through 5,000 feet (1,524 meters) when the #1 engine (the outboard engine on the left wing) caught fire. The engine was shut down and CO2 fire extinguishers were activated. Eddie Allen began a descent and turned back toward Boeing Field.

The wind was out of the south at 5 miles per hour (2.24 meters per second) so it was decided to land on Runway 13, the southeast/northwest runway. At 12:24, radio operator Harry Ralston reported that the XB-29 was 4 miles (6.4 kilometers) northeast of the field at 1,200 feet (366 meters).

The airplane was in the landing pattern turning from the downwind leg to the base leg when at 12:25 an explosion occurred. Ralston was heard to say, “Allen, better get this thing down in a hurry. The wing spar is burning badly.”

In order to save weight, the crank case of the Wright R-3350 engine was made of magnesium, a flammable metal which burned at a very high temperature. With an engine on fire, the bomber’s wing structure was extremely vulnerable.

The prototype bomber was now shedding parts and left a trail behind it on the ground. The fire was now burning inside the fuselage. Three crew members bailed out but the altitude was too low and they were killed.

At 12:26 p.m., Boeing XB-29 41-0003 crashed into the Frye Meat Packing Plant, south of downtown Seattle, and exploded. Nearly 5,000 gallons (18,927 liters) of gasoline started a massive fire. The 8 men still aboard the prototype bomber were killed, as were 20 employees inside the building. A firefighter who responded was also killed.

The Frye packing plant on fire, 18 February 1943. (Seattle Post Intelligencer)

Three XB-29 prototypes were built. The XB-29 was 98 feet, 2 inches (29.896 meters) long with a wing span of 141 feet, 3 inches (43.053 meters), and 27 feet, 9 inches (8.458 meters) high to the top of its vertical fin. The prototype bomber had a gross weight of 105,000 pounds (47,627.2 kilograms).

Boeing XB-29-BO, 41-002, the first XB-29 built. (U.S. Air Force)
Boeing XB-29-BO, 41-002, the first XB-29 built. (U.S. Air Force)

The XB-29 was powered by four 3,347.662-cubic-inch-displacement (54.858 liter) air-cooled, supercharged, Wright Aeronautical Division Cyclone 18 670C18H1 (R-3350-13) two-row 18-cylinder radial engines (also known as the Duplex-Cyclone) with a compression ratio of 6.85:1. The R-3350-13 had a Normal Power rating of 2,000 horsepower at 2,400 r.p.m., and 2,200 horsepower at 2,800 r.p.m. for takeoff, using 100 octane aviation gasoline. The engines turned 17-foot-diameter (5.182 meters) three-bladed Hamilton Standard Hydromatic constant-speed propellers through a 0.35:1 gear reduction. The R-3350-13 was 76.26 inches (1.937 meters) long, 55.78 inches (1.417 meters) in diameter, and weighed 2,668 pounds (1,210 kilograms).

The XB-29 had a maximum speed of 368 miles per hour (592 kilometers per hour) and cruised at 255 miles per hour (410 kilometers per hour). Its service ceiling was 32,100 feet (9,784 meters). The airplane was designed to carry 20,000 pounds (9,072 kilograms) of bombs.

The B-29 Superfortress was the most technologically advanced—and complex—aircraft of the War. It required the manufacturing capabilities of the entire nation to produce. Over 1,400,000 engineering man-hours had been required to design the prototypes. It would be manufactured by Boeing at Seattle and Renton, Washington and at Wichita, Kansas; by Glenn L. Martin Company at Omaha, Nebraska; and by Bell Aircraft Corporation, Atlanta, Georgia.

There were three XB-29 prototypes; 14 YB-29 pre-production test aircraft; 2,513 B-29; 1,119 B-29A; and 311 B-29B Superfortress aircraft. The bomber served during World War II and the Korean War and continued in active U.S. service until 1960.

The employees of the Boeing plant at Wichita, Kansas donated the money to build a B-29 to be named in honor of Eddie Allen. B-29-40-BW 42-24579 flew 24 combat missions. On its final mission over Tokyo, Japan, the Eddie Allen was so badly damaged that, though it was able to reach its base on the island of Tinian, it never flew again.

Boeing B-29 Superfortress "Eddie Allen." (U.S. Air Force)
Boeing Wichita-built B-29-40-BW Superfortress 42-24579, “Eddie Allen,” of the 45th Bombardment Squadron (Very Heavy), 40th Bombardment Group (Very Heavy), XX Bomber Command, circa 1944. (U.S. Air Force)
Boeing's acknoledgemnt of the sacrifice of its flight test crew, 18 February 1943,
Boeing’s acknowledgement of the sacrifice of its flight test crew, 18 February 1943, from the annual report to the shareholders.

© 2017, Bryan R. Swopes

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15 February 1961, 09:05 UTC

Boeing 707-329 OO-SJB, Sabena Flight 548. (© Guy Van de Merckt)
Boeing 707-329 OO-SJB, Sabena Flight 548. (© Guy Van de Merckt)
Commandant de Bord Ludovic Marie Antoine Lambrechts, Officier de l’Ordre del Couronne, Chevalier de l’Ordre de Leopold. (1917–1961)
Commandant de Bord Ludovic Marie Antoine Lambrechts, Officier de l’Ordre del Couronne, Chevalier de l’Ordre de Leopold. (1917–1961)

15 February 1961, 09:05 UTC: This Boeing 707-329 airliner, registration OO-SJB, under the command of Captain Ludovic Marie Antoine Lambrechts and Captain Jean Roy, was enroute from Idlewild Airport, New York (IDL) to Brussels-Zaventem Airport (BRU) as SABENA Flight SN548, when three miles (4.8 kilometers) short of the runway at an altitude of 900 feet (274 meters), it pulled up, retracted its landing gear and accelerated.

The airliner made three 360° circles, with the angle of bank steadily increasing to 90°. The 707’s wings then leveled, followed by an abrupt pitch up. OO-SJB spiraled into a nose-down dive and crashed into an open field 1.9 miles (3 kilometers) northeast of Brussels and all 61 passengers and 11 crew members and 1 on the ground were killed, including the entire U.S. Figure Skating Association team, their families, coaches, judges and officials.

Wreckage of Sabena Flight 548, 15 February 1961.
Wreckage of SABENA Flight SN548, Brussels, Belgium, 15 February 1961.

The cause of the crash was never determined but is suspected to be a mechanical failure in the flight control system:

Having carried out all possible reasonable investigations, the Commission concluded that the cause of the accident had to be looked for in the material failure of the flying controls. However, while it was possible to advance certain hypotheses regarding the possible causes, they could not be considered entirely satisfactory. Only the material failure of two systems could lead to a complete explanation, but left the way open to an arbitrary choice because there was not sufficient evidence to corroborate it.”

The Federal Aviation Administration commented that the most plausible hypothesis was a malfunction of the stabilizer adjusting mechanism permitting the stabilizer to run to the 10.5° nose-up position.

Societé Anonyme Belge d’Exploitation de la Navigation Aérienne (SABENA) was the national airline of Belgium. It was based at Brussels and operated from 1923 to 2001.

The United States Figure Skating Association team, boarding SABENA Flight SN548 at Idlewild Airport, New York, 14 February 1961. From left in front row are: Deane McMinn, Laurence Rochon Owen, Steffi Westerfeld and Rhode Lee Michelson. From left on the bottom: Douglas Ramsay, Gregory Kelley, Bradley Lord, Maribel Y. Owen, Dudley Richards, William Hickox, Ray Hadley Jr., Laurie Hickox, Larry Pierce, Ila Ray Hadley, Roger Campbell, Diane Sherbloom, Dona Lee Carrier, and Robert and Patricia Dineen. (U.S.F.S.A.)
The United States Figure Skating Association team, boarding SABENA Flight SN548 at Idlewild Airport, New York, 14 February 1961. From left in front row are: Deane McMinn, Laurence Rochon Owen, Steffi Westerfeld and Rhode Lee Michelson. From left on the bottom: Douglas Ramsay, Gregory Kelley, Bradley Lord, Maribel Y. Owen, Dudley Richards, William Hickox, Ray Hadley Jr., Laurie Hickox, Larry Pierce, Ila Ray Hadley, Roger Campbell, Diane Sherbloom, Dona Lee Carrier, and Robert and Patricia Dineen. (U.S.F.S.A.)
This February 13, 1961 edition of Sports Illustrated was found in the burned-out wreckage of SABENA SN548. U.S.F.S.A. figure skater Laurence Rochon Owen’s photograph is on the cover. The 16-year-old skater is second from the left in the team photograph, above.
This February 13, 1961 edition of Sports Illustrated was found in the burned-out wreckage of SABENA SN548. U.S.F.S.A. figure skater Laurence Rochon Owen’s photograph is on the cover. The 16-year-old skater is second from the left in the team photograph, above.

SABENA Flight SN548 was a Boeing 707-329 Intercontinental. OO-SJB, Boeing serial number 17624, was nearly a new aircraft. It made its first test flight 31 December 1959 at Renton, Washington, and was delivered to SABENA 15 January 1960. At the time of the accident, it had just 3,038 total flight hours (TTAF).

The Boeing 707 was a jet airliner which had been developed from the Model 367–80 prototype, the “Dash Eighty.” It 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 707-329 Intercontinental is 152 feet, 11 inches (46.611 meters) long with a wing span of 145 feet, 9 inches (44.425 meters). The top of the vertical fin stands 42 feet, 5 inches (12.928 meters) high. The wing is considerably different than on the original 707-120 series, with increased length, different flaps and spoilers, and the engines are mounted further outboard. The vertical fin is taller, the horizontal tail plane has increased span, and there is a ventral fin for improved longitudinal stability.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 146,400 pounds (66,406 kilograms). Maximum take off weight (MTOW) is 333,600 pounds (151,320 kilograms). At MTOW, the 707-329 required 10,840 feet (3,280 meters) of runway to take off.

OO-SJB was powered by four Pratt & Whitney JT4A turbojet engines, producing 15,800 pounds of thrust, each. Its maximum speed is 0.80 Mach (552 miles per hour, or 889 kilometers per hour). It had a range of 4,298 miles (6,920 kilometers).

The Boeing 707 was in production from 1958 to 1979. 1,010 were built.

The cover of the 13 February 1961 edition of Sports Illustrated. (SI)
The cover of the 13 February 1961 edition of Sports Illustrated. (SI)

© 2017, Bryan R. Swopes

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13 February 1950

Convair B-36B-1-CF Peacemaker of the 7th Bombardement Wing. (U.S. Air Force)
Convair B-36B-1-CF Peacemaker, 44-92033, of the 7th Bombardment Wing (Heavy). This bomber is similar to 44-92075. (U.S. Air Force)

13 February 1950: Two Convair B-36B Peacemaker long-range strategic bombers of the 436th Bombardment Squadron (Heavy), 7th Bombardment Wing (Heavy), Strategic Air Command, departed Eielson Air Force Base, Fairbanks, Alaska at 16:27 Alaska Standard Time, on a planned 24-hour nuclear strike training mission. B-36B-15-CF 44-92075 was under the command of Captain Harold L. Barry, U.S. Force. There were a total of seventeen men on board.

Also on board was a Mark 4 nuclear bomb.

The B-36s were flown to Alaska from Carswell Air Force Base, Fort Worth, Texas, by another crew. The surface temperature at Eielson was -40 °F. (-40 °C.), so cold that if the bomber’s engines were shut down, they could not be restarted. Crews were exchanged and the airplane was serviced prior to takeoff for the training mission. In addition to the flight crew of fifteen, a Bomb Commander and a Weaponeer were aboard.

After departure, 44-92075 began the long climb toward 40,000 feet (12,192 meters). The flight proceeded along the Pacific Coast of North America toward the practice target of San Francisco, California. The weather was poor and the bomber began to accumulate ice on the airframe and propellers.

About seven hours into the mission, three of the six radial engines began to lose power due to intake icing. Then the #1 engine, outboard on the left wing, caught fire and was shut down. A few minutes later, the #2 engine, the center position on the left wing, also caught fire and was shut down. The #3 engine lost power and its propeller was feathered to reduce drag. The bomber was now flying on only three engines, all on the right wing, and was losing altitude. When the #5 engine, center on the right wing, caught fire, the bomber had to be abandoned. It was decided to jettison the atomic bomb into the ocean.

The Mark 4 did not have the plutonium “pit” installed, so a nuclear detonation was not possible. The conventional explosive would go off at a pre-set altitude and destroy the bomb and its components. This was a security measure to prevent a complete bomb from being recovered.

The bomb was released at 9,000 feet (2,743 meters), north-northwest of Princess Royal Island off the northwest coast of British Columbia, Canada. It was fused to detonate 1,400 feet (427 meters) above the surface, and crewmen reported seeing a large explosion.

Flying over Princess Royal Island, Captain Barry ordered the crew to abandon the aircraft. He placed the B-36 on autopilot. Barry was the last man to leave 44-92075. Descending in his parachute, he saw the bomber circle the island once before being lost from sight.

Twelve of the crew survived. Five were missing and it is presumed that they landed in the water. Under the conditions, they could have survived only a short time. The survivors had all been rescued by 16 February.

It was assumed that 44-92075 had gone down in the Pacific Ocean.

On 20 August 1953, a Royal Canadian Air Force airplane discovered the wreck of the missing B-36 on a mountain on the east side of Kispiox Valley, near the confluence of the Kispiox and Skeena Rivers in northern British Columbia.

The U.S. Air Force made several attempts to reach the crash site, but it wasn’t until August 1954 that they succeeded. After recovering sensitive equipment from the wreckage, the bomber was destroyed by explosives.

Bomb, Mark 4. (Nuclear Weapons Archive)
Bomb, Mark 4. (Nuclear Weapons Archive)

The Mark 4 bomb was a development of the World War II implosion-type Mark 3 “Fat Man.” The bomb was 10 feet, 8 inches (3.351 meters) long with a maximum diameter of 5 feet, 0 inches (1.524 meters). Its weight is estimated at 10,800–10,900 pounds (4,899–4,944 kilograms).

The core of the bomb was a spherical composite of plutonium and highly-enriched uranium. This was surrounded by approximately 5,500 pounds (2,495 kilograms) of high explosive “lenses”—very complex shaped charges designed to focus the explosive force inward in a very precise manner. When detonated, the high explosive “imploded” the core, crushing it into a smaller, much more dense mass. This achieved a “critical mass” and a fission chain reaction resulted.

The Mark 4 was produced with explosive yields ranging from 1 to 31 kilotons. 550 were built.

Convair B-36B-15-CF Peacemaker 44-92075 was completed at Fort Worth, Texas, on 31 July 1949. It had been flown a total of 185 hours, 25 minutes.

The B-36B is 162 feet, 1 inch (49.403 meters) long with a wingspan of 230 feet (70.104 meters) and overall height of 46 feet, 8 inches (14.224 meters). The empty weight is 140,640 pounds (63,793 kilograms) and the maximum takeoff weight was 311,000 pounds (141,067 kilograms).

With a wing area of 4,772 square feet (443 square meters) and 21,000 horsepower, the B-36 could fly far higher than any jet fighter of the early 1950s.

A Pratt & Whitney R-4360-41 Wasp Major aircraft engine on display at the National Museum of the United States Air Force. This engine weighs 3,404 pounds (1,544 kilograms). Wikipedia
A Pratt & Whitney Wasp Major B4 (R-4360-41) aircraft engine on display at the National Museum of the United States Air Force. This engine is 9 feet, 1¾-inch (2.788 meters) long and 4 feet, 6 inches (1.372 meters) in diameter. It weighs 3,567 pounds (1,618 kilograms). Wikipedia

The B-36B was powered by six air-cooled, supercharged and turbocharged 4,362.49 cubic-inch-displacement (71.488 liter) Pratt & Whitney Wasp Major B4 (R-4360-41) four-row, 28-cylinder radial engines placed inside the wings in a pusher configuration. These had a compression ratio of 6.7:1 and required 115/145 aviation gasoline. The R-4360-41 had a Normal Power rating of 2,650 horsepower at 2,550 r.p.m. Its Takeoff/Military Power rating was 3,500 horsepower at 2,700 r.p.m., with water injection. The engines turned three-bladed Curtiss Electric constant-speed, reversible propellers with a diameter of 19 feet, 0 inches (5.791 meters) through a 0.375:1 gear reduction. The R-4360-41 is 9 feet, 1.75 inches (2.788 meters) long, 4 feet, 6.00 inches (1.372 meters) in diameter, and weighs 3,567 pounds (1,618 kilograms).

The B-36B Peacemaker had a cruise speed of 202 miles per hour (325 kilometers per hour) and a maximum speed of 381 miles per hour (673 kilometers per hour) at 34,500 feet (10,516 meters). The service ceiling was 42,500 feet (12,954 meters) and its combat radius was 3,740 miles (6,019 kilometers). The maximum range was 8,175 miles (13,156 kilometers).

The B-36 was defended by sixteen M24A-1 20 mm automatic cannons. Six retractable gun turrets each each had a pair of 20 mm cannon, with 600 rounds of ammunition per gun. These turrets were remotely operated by gunners using optical sights. Two optically-sighted 20 mm guns were in the nose, and two more were in a tail turret, also remotely operated and aimed by radar.

In this photograph, two of the B-36's retractable gun turrets are visibile behind the cockpit, as well as the nose gun turret. (Unattributed)
In this photograph, two of the B-36’s retractable gun turrets are visible behind the cockpit, as well as the nose gun turret. The plexiglas “blister” just ahead and below the dorsal turrets is a gunner’s sighting station. The bomb bay doors are open. (Unattributed)

The B-36 was designed during World War II and nuclear weapons were unknown to the Consolidate-Vultee Aircraft Corporation engineers. The bomber was built to carry up to 86,000 pounds (39,009 kilograms) of conventional bombs in the four-section bomb bay. It could carry the 43,600 pound (19,777 kilogram) T-12 Cloudmaker, a conventional explosive earth-penetrating bomb. When armed with nuclear weapons, the B-36 could carry several Mk.15 thermonuclear bombs. By combining the bomb bays, one Mk.17 25-megaton thermonuclear bomb could be carried.

Between 1946 and 1954, 384 B-36 Peacemakers were built by Convair. 73 of these were B-36Bs, the last of which were delivered to the Air Force in September 1950. By 1952, 64 B-36Bs had been upgraded to B-36Ds.

They were never used in combat. Only five still exist.

[Trivia enthusiasts might note that the U.S. military code for a lost nuclear weapon is “Broken Arrow.” In 1950, Academy Award-winning actor Jimmy Stewart, himself a Brigadier General, U.S. Air Force Reserve, and highly decorated World War II bomber commander, starred in the Delmer Daves western movie, “Broken Arrow.” In 1954, Stewart starred as a B-36 aircraft commander in Anthony Mann’s “Strategic Air Command.” Coincidence?]

© 2017, Bryan R. Swopes

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12 February 1935

USS Macon (ZRS-5) recovering two Curtiss F9C Sparrowhawk scout biplanes. (U.S. Navy)
USS Macon (ZRS-5) recovering two Curtiss F9C Sparrowhawk scout biplanes. (U.S. Navy)

12 February 1935: The United States Navy rigid airship USS Macon (ZRS-5), under the command of Lieutenant Commander Herbert Victor Wiley, crashed into the Pacific Ocean off Monterey Bay, on the central California coastline. The airship soon sank to the sea floor, approximately 1,500 feet (457 meters) below. Of the crew of 76 men, 74 survived.

Captain Herbert Victor Wiley, United States Navy

Lieutenant Commander Wiley was a 1915 graduate of the United States Naval Academy, Annapolis, Maryland. He had previously served aboard the U.S. Navy’s first rigid airship, USS Shenandoah (ZR-1) and then commanded USS Los Angeles (ZR-3), 1929–1930. He had been assigned as executive officer of USS Akron (ZRS-4) and had been one of only 3 crew members to survive the wreck of that airship off the coast of New Jersey, 4 April 1933. He took command of USS Macon in June 1934. During World War II, Captain Wiley commanded Destroyer Squadron 29 (consisting of thirteen Clemson-class “flush-deck” destoyers) with the Aisatic Fleet, and later, the Colorado-class battleship USS West Virginia (BB-48). He rose to the rank of rear admiral before retiring in 1947.

USS Macon was built by the Goodyear-Zeppelin Corporation at Akron, Ohio. It was launched 21 April 1933, and commissioned 23 June 1933.

USS Macon (ZRS-5) under construction at the Goodyear Airdock, Akron, Ohio, 1933. (U.S. Navy)

Macon was constructed of duralumin ring frames and girders, covered with a fabric envelope. The rigid airship was 785 feet (239.3 meters) long with a maximum diameter of 132 feet, 10 inches (40.488 meters). The overall height was 146 feet, 2 inches (44.552 meters). The airship displaced 7,401,260 cubic feet of air (209,580 cubic meters). Lift was provided by 6,500,000 cubic feet (184,060 cubic meters) of non-flammable helium gas contained in 12 rubberized fabric gas cells.

Macon had a dead weight of 108.2 tons (98,157 kilograms) and a useful lift of 160,644 pounds (72,867 kilograms).

Maybach VL-2 60° V-12 in the collection of the National Air and Space Museum. (NASM)

Propulsion was provided by eight water-cooled, fuel-injected, 33.251 liter (2,029.077-cubic-inch-displacement) Maybach VL-2 overhead valve 60° V-12 gasoline engines producing a maximum 570 horsepower at 1,600 r.p.m., each, or 450 horsepower at 1,400 r.p.m. for cruise. In addition to gasoline, the VL-2 could also use blau gas (similar to propane) as fuel. The engines were reversible and drove Allison Engineering Co. out-drives, which turned three-bladed fixed-pitch, rotatable propellers. The VL-2 is 6 feet, 5 inches (1.96 meters) long, 3 feet, 0 inches (0.91 meters) wide and 3 feet, 2 inches (0.97 meters) high. It weighs 2,530 pounds (1,148 kilograms).

The airship had a maximum speed of 75.6 knots (87.0 miles per hour, 140.0 kilometers per hour).

USS Macon was armed with eight Browning .30-caliber machine guns for defense. It also carried five Curtiss-Wright Airplane Division F9C-2 Sparrowhawk reconnaissance airplanes in an internal hangar bay. These were small single-place, single-engine biplanes, with a length of 20 feet, 7 inches (6.274 meters) and wingspan of 25 feet, 5 inches (7.747 meters). The Sparrowhawk had an empty weight of 2,114 pounds (959 kilograms) and loaded weight of 2,776 pounds (1,259 kilograms).

The F9C-2 was powered by an air-cooled, supercharged, 971.930-cubic-inch displacement (15.927 liter) Wright Aeronautical Division Whirlwind R-975E-3 (R-975-11, -24 or -26) nine-cylinder radial engine with a compression ratio of 6.3:1. The R-975E-3 had a normal power rating of 420 horsepower at 2,200 r.p.m., and 440 to 450 horsepower at 2,250 r.p.m. for takeoff, depending on variant. These were direct drive engines which turned two-bladed propellers. They were 3 feet, 7.00 inches to 3 feet, 7.47 inches (1.092–1.104 meters) long, 3 feet, 11 inches to 3 feet, 11.25 inches (1.143–1.149 meters) in diameter, and weighed from 660 to 700 pounds (299–317.5 kilograms).

The Sparrowhawk had a maximum speed of 176 miles per hour (283 kilometers per hour), a range of 297 miles (478 kilometers) and a service ceiling of 19,200 feet (5,852 meters).

The airplane was armed with two fixed Browning .30-caliber machine guns, synchronized to fire forward through the propeller arc.

Four of Macon‘s fighters, Bureau of Aeronautics serial numbers A9058–A9061, were lost when the airship went down.

Curtiss F9C-2 Sparrowhawk, Bu. No. 9056. (U.S. Navy)
Curtiss-Wright F9C-2 Sparrowhawk, Bu. No. A9056. (U.S. Navy)

During an earlier transcontinental flight, USS Macon had encountered severe turbulence while crossing mountains in Arizona. A diagonal girder in one of the ring frames failed. Temporary repairs were made, but permanent repairs were deferred until the next scheduled overhaul.

On 12 February 1935, the airship flew into a storm near Point Sur, California. The ring frame failed and the upper vertical fin was lost. Pieces of broken girders punctured several of the aft helium cells.

With the loss of helium, Macon lost rear buoyancy and began to settle. To compensate, all engines were run at full power and ballast was released. The airship began to climb with a nose-up pitch angle. When it passed 2,800 feet (853.4 meters) altitude, it reached its Pressure Altitude Limit. At this point, expanding helium began to vent from the gas cells. Macon continued rising until reaching 4,850 feet (1,478.3 meters), by which time it had lost so much helium that the engines could no longer keep it airborne and it again began to settle toward the ocean’s surface. The descent took twenty minutes.

One sailor jumped from the airship, but did not survive the fall. Another swam back to the sinking ship to collect personal belongings and drowned. The rest of the crew was rescued by the light cruiser USS Richmond (CL-9).

USS Macon was the U.S. Navy’s last rigid airship. For the next twenty years, all lighter-than-air craft were non-rigid “blimps”.

USS Macon (ZRS-5) is seen from directly below as it passes over San Diego, California, 9 February 1934. (U.S. Navy)
USS Macon (ZRS-5) is seen from directly below as it passes over San Diego, California, 9 February 1934. (U.S. Navy)

© 2017, Bryan R. Swopes

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