Mention the phrase “private jet” to the average person and one word immediately pops into mind: Lear. Since its first flight in 1963, William P. Lear Sr.'s innovative aircraft, built to replicate the performance and amenities of a commercial airliner, has been tantamount with executive business travel.  

One of the inventors of the 8-track audio tape, the holder of 150 aviation-related patents and a high school drop-out, Lear abandoned his retirement in Switzerland to establish the Swiss American Aircraft Company (SAAC). In 1959, SAAC began work on Lear's latest invention—a private luxurious jet aircraft with the flexibility to fly passengers and freight in and out of small airports around the world. Lear undertook his bold gamble without the benefit of a market survey to evaluate the consumer demand for such an aircraft, relying instead on pure intuition. 

Inspired by a single-seat Swiss strike fighter aircraft, the FFA P-16 (flown as a prototype in April 1955 but never put into production), Lear recruited a group of Swiss aircraft designers and engineers to transform the fighter's wing and basic airframe design into the cornerstone of a revolutionary aircraft—originally designated as the SAAC-23 but soon renamed as the Learjet 23 Continental. 

Problems with suppliers and production tooling in Switzerland compelled Lear to shift assembly of the new aircraft to Wichita, Kansas (under the new name of Lear Jet Industries), where the prototype Learjet 23 made its first flight on October 7, 1963, from Wichita's Mid-Continent Airport, nine months after work had begun on the project. The original Learjet accumulated 194 hours of flight time in 167 test flights until it was destroyed in June 1964 when it crashed at takeoff with a Federal Aviation Administration pilot at the controls. The cause of the accident was determined to be pilot error—retraction of the jet's lift spoilers was overlooked. However, a second prototype Learjet 23 soon received formal FAA certification on July 31, 1964. 

The Learjet 23 became the first small jet aircraft to enter mass production as well as the first to be developed and financed by a single individual. Chemical and Industrial Corporation of Cincinnati, Ohio, took delivery of the first production Learjet on October 13, 1964, one year after its initial flight.  

The 43-foot (13-meter) long Learjet 23 had a wingspan of 35.5 feet (10.8 meters), weighed 12,750 pounds (5,783 kilograms) empty, and was powered by a pair of General Electric CJ610-4 turbojet engines. The original Model 23 was a seven-passenger jet (later increased to nine) including two pilots, fully pressurized with windshield and large cabin windows fabricated from stretched and laminated acrylic plastic. It could fly at a top speed of 564 miles per hour (908 kilometres per hour) with a range of 1,875 miles (3,018 kilometres). 

Lear authorized a series of demonstration flights to showcase the aircraft's capabilities by establishing several new world aviation records. On May 21, 1965, pilots John Conroy and Clay Lacey, with five passengers on board, flew a Learjet 23 on a 5,005-mile (8,055-kilometers) roundtrip from Los Angeles to New York and back in just 11 hours, 36 minutes. Seven months later, on December 14, 1965, pilots Henry Beaird and Ronald Puckett, plus five observers, climbed to an altitude of 40,000 feet (12,192 meters) in a Learjet 23 in 7 minutes, 21 seconds—the new jet demonstrating that it could climb to 10,000 feet (3,048 meters) faster than an F-100 Super Sabre fighter jet!  

The new business jet was an immediate commercial success, with more than 100 sold by the end of 1965 at an initial price of $540,000 each. Unfortunately, the original Learjet 23 also developed an unwanted reputation as a very demanding and unforgiving aircraft for the average pilot to fly—a major factor in the strategic decision to quickly design a successor.  

The undisputed marketing success of the Learjet 23 spurred development of a new aircraft with improved low-speed handling characteristics, coupled with increased range, size, and speed. Approximately 105 Learjet 23s were built from 1963 to 1966 until replaced by the improved Model 24 (the 150^th Learjet built), which made its debut in March 1966. 

The all-metal fuselage of the Learjet 24 was a flush-riveted semi-monocoque design. It was equipped with wingtip fuel tanks that added 364 extra gallons (1,378 liters) of fuel capacity and featured the added attraction of a "T-tail" configuration.  

Lear Jet again quickly embarked on a campaign to demonstrate the improved aircraft's performance. In the span of just four days, from May 23 to 26, 1966, the Learjet 24 became the first business jet to circumnavigate the globe, travelling 22,993 miles (37,004 kilometres) in 50 hours and 20 minutes of flying time, establishing or breaking 18 aviation world records during the flight. In all, 259 Learjet 24s were produced. 

The high cruising altitude and long endurance flight capability of the Learjet also made it an ideal aircraft for target towing, photo-surveying, and high-altitude mapping. A number of foreign Air Forces, including Bolivia, Ecuador, Argentina, Mexico, Peru, and Yugoslavia, modified the corporate jet for military missions. 

As the private jet market became more competitive, Lear Jet had difficulties remaining profitable and substantial operating losses accumulated over the first few years of production. In 1967, the company was sold to Gates Rubber Company of Denver, Colorado, and renamed the Gates Learjet Corporation; since 1990, the jets have been produced by the Canadian corporation Bombardier under the name of Learjet, Inc.