The First Pressurized Commercial Aircraft: 83 Years Of The Boeing 307 Stratoliner

Today marks 83 years since the Boeing 307 Stratoliner flew for the very first time. The aircraft performed its maiden flight on December 31st, 1938, introducing a new era in commercial aviation, which would have an impact on the global industry nearly a century later.

Boeing 307 Stratoliner "Clipper Flying Cloud
The aircraft could cruise at 20,000 ft (6,096 m) while maintaining a cabin pressure of 8,000 ft (2,438 m), enabling airlines to operate well despite usually tough conditions. Photo: Getty Images

Based on another legend

The wings, tail, and engines of the Boeing B-17C bomber were incorporated into the plane, and the interior was fitted with sleeper berths and reclining seats. The 307’s circular fuselage offered additional space for its five crew members and 33 guests. Moreover, the cabin had a width of nearly 12 feet (3.6 meters), which was plenty of room for good nights’ sleep on the berths during overnight transcontinental and international flights.

Registration NX 19901 took flight for the first time from Boeing Field on New Year’s Eve, 1938. The aircraft sadly crashed on March 18th, 1939 during a demonstration flight to KLM representatives. All 10 people on board died as a result of the accident.

Despite the tragedy and related challenges, five units made their way to TWA, and three were taken on by Pan American.

Boeing 307
In total, 10 Stratoliners were produced. Photo: Getty Images

High specifications for the time

Four Wright GR-1820-G102A radial engines, with 1100 hp (820 kW) each powered the plane. These units helped the aircraft reach a maximum speed of 241 mph (387 km/h), a cruise speed of 215 mph (344 km/h), and a range of 1,520 NM (2,820 km). There were also new heights reached when it came to the service ceiling.

“The Boeing Model 307 Stratoliner was the world’s first high-altitude commercial transport and the first four-engine airliner in scheduled domestic service. With names such as Rainbow, Comet, Flying Cloud and Apache, the Stratoliner set new standards for speed and comfort. Its pressurized cabin allowed the airplane to soar above rough weather at an altitude of 20,000 feet (6,096 meters) — higher than any other transport of its time,” Boeing shares.

“Its circular fuselage provided maximum space for the five crew members and 33 passengers. The nearly 12-foot-wide (3.6-meter-wide) cabin had space for comfortable berths for overnight travelers. The Stratoliner was the first airplane to have a flight engineer as a member of the crew. The engineer was responsible for maintaining power settings, pressurization and other subsystems, leaving the pilot free to concentrate on other aspects of flying the aircraft.”

The sole surviving Boeing S-307 Stratoli
The 307 Stratoliner has a length of 74 ft 4 in (22.6 m), a height of 20 ft 9.5 in (6.33 m), and a wingspan of 107 ft 0 in (32.63 m). Photo: Getty Images

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Notable attention

In 1939, Howard Hughes, who had some sort of presence in all corners of US society and industry, including the leadership of TWA, acquired the first 307 Stratoliner. He overhauled the interior into what was dubbed a flying penthouse. A master bedroom, two bathrooms, a bar, a living room, and a galley could be found on board the plane.

Hughes had hoped to use the aircraft to break his own round-the-world flight record. However, Germany’s invasion of Poland in September that year made an attempt unsafe. So, the plan was scrapped. The aircraft was then sold to a Texas-based oil tycoon before becoming a houseboat in Florida.

In commercial service

1940 was an integral year for the Stratoliner program. Deliveries began in March, with Pan Am receiving the first unit. TWA then started receiving the type in April. That year, the two US powerhouses began flying the plane across the Americas. Pan Am’s units could be seen flying over the Caribbean Sea from Miami to Latin America. Meanwhile, TWA’s holdings were found on transcontinental routes between Los Angeles and New York.

PanAm Over Mt Ranier
Even though the luxuries of Hughes’ modified edition weren’t found on the passenger units, it was still a classy experience on board the plane. Photo: Getty Images

Production of the 307 came to an end amid the escalation of World War II. With the rise of the conflict, the plane was entrusted to carry the Army Transport Command as C-75 military transports. The cabin’s distinct pressurization system was taken out to save weight on crucial military missions.

The United States Army Air Forces wasn’t the only military group to operate the type. The Haitian Air Force also took on an ex-Pan Am unit as a presidential transport in 2003.

Along with TWA and Pan Am, four other passenger airlines operated the Stratoliner. These carriers were:

  • Cambodia Air Commercial (Cambodia)
  • Aerovias Ecuatorianas CA (Ecuador)
  • Aigle Azur (France)
  • Royal Air Lao (Laos)

The last remaining Stratoliner was operated by Pan Am as Clipper Flying Cloud. It was taken on by the Smithsonian’s National Air and Space Museum in 1969. Boeing then restored the plane in 2001 after it sat in the Arizona desert for two decades.

The unit, holding registration NC19903, ditched in Puget Sound in 2002 during a test flight but was restored by the following year. The plane can be spotted at the Steven F. Udvar-Hazy Center Smithsonian National Air and Space Museum’s annex at Washington Dulles International Airport.

The interior of the sole surviving Boein
An August 2003 photo inside of the sole surviving Boeing S-307 Stratoliner after its final landing ever before being placed on display. Photo: Getty Images

New opportunities in the market

Overall, thanks to the 307 Stratoliner, pressurization was introduced to the commercial aviation world. This feature went on to become a mainstay in the scene and helped airlines across the globe venture new heights over the years.

Commercial planes operate best at high altitudes. They are able to avoid potential harsh weather below while enhancing fuel efficiency. Thus, the 307, which was nicknamed the Flying Whale, kicked off a series of technological advancements. The first digital electronic cabin pressure control processes made their way to the market in 1977. Fully-automatic digital cabin pressure control systems that utilized converging nozzle thrust recovery valves were then introduced two years later.

The modern solutions have come a long way since the Stratoliner’s offering. However, airlines would have undoubtedly appreciated the breakthrough over eight decades ago.

What are your thoughts about the Boeing 307 Stratoliner and its operations? What do you make of the history of the iconic aircraft? Let us know what you think of the plane and its story in the comment section.