# Transportation Deployment Casebook/2023/U.S. Airliners
## U.S. Airliners Introduction
### Airliners Technical Characteristics

Airliners are designed to transport people and cargo for commercial purposes. They come in all sizes and types, from small regional jets to large wide-body aircraft capable of carrying hundreds of passengers. The type of engine used to power airliners varies depending on the era and design of the aircraft. Early airliners typically used piston engines, while later models transitioned to jet engines. Today turbofan engines are the preferred choice for modern airliners. Despite changes in engine technology, the basic principles of aerodynamics remain the same, including the use of Bernoulli's principle to create lift by increasing speed to create pressure differences. Technological advances in aircraft design and engineering have led to the development of more efficient and reliable airliners that have revolutionized the way humans travel and conduct business.

### Advantages

The same advantage offered by airliners of different eras is that they offer mankind a faster option for domestic and international travel, saving travel time by ship, train and car for the same distance. From the advent of the airliner in 1926 to the airliners that can carry large amounts of cargo, to now can carry more than 800 passengers at a time, regardless of the number of passengers, flying has been the fastest option for travel.
The advantage of the modern airliner is that it is one of the safest travel options available today. Advanced technology, rigorous training programs and strict regulations have all contributed to air travel safety. Airliners are also environmentally friendly, producing fewer carbon emissions per passenger mile than other modes of transportation. The latest airliners have been designed with passenger comfort in mind, offering a range of amenities such as in-flight entertainment, food and beverage service and wireless Internet access. These features have made air travel a popular choice for many passengers.

### U.S. Airliner Market

In the early days of the U.S. aviation industry, flying machines were used primarily in the U.S. air mail market. The market for airliners was limited due to a lack of infrastructure and technology. The market for airliners in the U.S. really opened up after the use of stock bombers converted to commercial use after World War I. Between 1940 and 1980, airliners became more complex and efficient due to advances in engineering and manufacturing. The growth of the airliners market was accelerated by an increase in the number of passengers carried per aircraft, which led to lower fares, at a time when large companies such as Boeing and Douglas dominated the aviation industry. Today, Boeing's acquisition of Douglas has led the airliners market in the United States and around the world, with the only competitor being France's Airbus.
The growth of the airliner market is slowing down, with the Covid-19 epidemic as a starting point and fewer people choosing to travel internationally. The 5G network era has allowed more people to telecommute to meetings and schools. Airlines are also retiring more high-capacity aircraft, such as the Airbus A380 and Boeing 747. But global demand for passenger aircraft is still on the rise, with 44,500 new aircraft still to be delivered worldwide over the next 20 years, but with a preference for medium capacity aircraft. From the perspective of airliner design making more passengers enjoy better flight comfort will become the main goal of the future airliner market.

## Transportation Modes before the Airliner

Before the advent of airliners, long-distance travel was still largely dependent on two modes of transportation: ships, and trains. While transoceanic travel would only rely on ships to travel. The use of trains or ships will be more obvious in the speed limitations, slower travel speed leads to more time spent in traffic. In the early 1900s, the RMS Olympic cruise across the Atlantic Ocean takes nearly 15 days. And at the time U.S. railroad system was in its heyday. From New York to Iowa also consumed at least a day of time to travel by railroads. At the time, cruises and trains were seen as a more affluent way to travel, so they would have been a good choice for travel comfort. From the perspective of travel efficiency, businesspeople and professionals will need a longer time for long-distance travel. The time consumed was unacceptable to the United States in the Gilded Age, and the disparity between the rich and the poor was extremely serious at the time, coupled with the unrestricted expansion of railroads that led to strikes by American labourers and other negative effects on the railroad mode of transportation itself. Therefore, a faster and more convenient mode of transportation needed to be discovered.

## Invention of the Airliner

The invention of the "1903 Wright Flyer", the world's first airplane, led to the development of aviation leading to the emergence of airliners. In the early 19th century, the aerodynamic angle of the glider wing design entered the public eye. At that time the main technical barrier is how to generate sustained power for flight. The Russians had tried steam power with poor results. In 1876, when Étienne Lenoir manufactured the first internal combustion engine, successfully laying the theoretical power foundation for aircraft, allowing the Wright brothers to manufacture their four-cylinder engine as an aircraft engine and successful flight marked the official emergence of aviation.
Fifteen years later, in 1918, the United States officially began airmail service with the "Jenny" Curtiss JN-4H biplane, built by the U.S. Army and Navy, and from 1918 to 1926, there were more than 200 airmail pilots, 35 of whom died in airplane accidents. The danger factor of the aircraft was still at a high level until the end of World War I, when a large number of retired American bombers, the De Havilland DH-4, were turned over to the airmail industry. At a time when the bomber was considered a safer, faster and superior aircraft.The DH-4 proved to be a great challenge to the railroad industry by greatly reducing transit times over long distances, and the time-sensitive financial industry increased its support for the airmail industry at a time when the use of mail for check and securities transactions was extremely common. The rapid growth of the airmail industry led to congressional attention and eventually to the "Contract Air Mail Act of 1925" and the "Air Commerce Act". These two acts made it possible for the airmail industry to be privately contracted and ensured that outside investment would be secure. Also for all people and businesses to safely participate in the airline industry, increasing the opportunity for competition and accelerating the growth of the airliner industry. Beginning in 1925, with policy support, aircraft manufacturing began to develop rapidly, with new fairing designs, piston engines, variable pitch propellers, and other new aircraft designs appearing in large numbers.The first airliner, the Boeing 247, was introduced, with an unprecedented speed (290 km/h) and the ability to carry up to 10 passengers and three crew members, and received an order for $3.5 million at the time. It entered service with United Airlines on May 22, 1933. This successfully opened the chapter on passenger aircraft.

## Life cycle of U.S. Airliners
### Early market for U.S. airliners (1926-1960)

The introduction of the Boeing 247 officially opened up the early market for piston-engine airliners. Before that, many airlines were trying to make a profit by transporting passengers, and all passenger airlines before the Boeing 247 failed due to high operating costs, and the U.S. federal government had to introduce various subsidies to encourage the development of airliners, including the aforementioned "Contract Air Mail Act" and the "Air Commerce Act". In 1930, the "McNary-Watres Act-The Airmail Act" was enacted to allow mail and airliner routes to be combined and to increase the number of routes as judged. This act has greatly stimulated the airline industry, with more routes to choose from giving more people the option to travel by air, and a large number of newly developed routes boosting the demand for passenger aircraft. With the advent of the Boeing 247 in 1933, high-profit returns led to more companies competing for airliners, and the Douglas Aircraft Company seized the opportunity of the crash of the Boeing 247 in Kansas to produce the DC-2. In 1936, it developed an improved version of the DC-3, which could already carry 21 passengers and was responsible for 90 percent of the world's air traffic.From 1936, when the DC-3 appeared, the number of passengers grew from 100,000 per year to 1 million per year. During this time, the "Civil Aeronautics Act" was enacted and the Civil Aeronautics Administration(CAA) of the United States was officially established, and the airliner officially shifted to the passenger-oriented airliner market.
And such growth came to a brief halt two years after the start of the Pacific War, but the war led to rapid growth in aircraft engineering, And once again Boeing developed the Boeing 307 Stratoliner based on the B-17 bomber design. The world's first airliner that could carry 40 people into the stratosphere.The world's first airliner that could carry 40 people into the stratosphere. And from 1942 after the Battle of Midway, the fact that America will win this war has been well-known to Americans. So in 1943, the number of airliners enplaned passengers back to the level of 1941 and continue to grow in increments of 3 million passengers per year, the late addition of larger capacity passenger aircraft such as the Boeing 307 and DC-4 to make from 1952 to 5 million passengers per year to grow, thus opening the passenger aircraft The era of rapid passenger development began.
The early airliner market evolved from the invention of technology to policy changes, and finally to the development of technology. The early U.S. airliner subsidy policies and related programs for airliner transportation were influenced by the use of policies that allowed airliner development to grow.

### The Developing U.S. Airliner Market (1960-2000)

The stage of development of U.S. airliners is one of the more complex stages in the history of global aviation, and this chapter will focus on technology and policy, the two fundamental factors that have changed the stage of development of U.S. airliners. In fact, economic, political and environmental factors have all played a role in the developing U.S. airliner market and will not be discussed in this chapter.

#### Technology

The Second World War led to jet engine technology. Boeing once again derived a jet airliner based on the bomber (B-47).In 1954, the first U.S. jetliner, the Boeing 707, made a test flight and can carry nearly 200 passengers in a single trip. The first flight was made in 1957, and the market for transoceanic flights and long-distance flights was then fully opened. From 1960 to 1970, the Boeing 707 captured most of the market, and from 1970 onward, the Boeing 747 and Boeing 737 were produced, establishing a monopoly for Boeing in the U.S. airliner market. Airliner technology also reached its peak in this period.

#### Policy

The first change in policy is regarding the safety of airliners. Beginning around the 1950s, aviation development made U.S. airspace very congested, and two airliner crashes in 1956 and 1958 demonstrated that the air traffic controls applied by the Civil Aeronautics Administration (CAA) were outdated. In 1958, Eisenhower signed the "Federal Aviation Act", which eliminated the Civil Aeronautics Administration and created the Federal Aviation Administration (FAA), which re-regulated the safety of the aviation industry and the use of U.S. airspace by both civilian and military aircraft.
The second was the "Airport and Airway Development Act of 1970", which provided funding for airport development by increasing taxes on fuel, airline tickets, and other taxes. This act was created in response to the needs of the aviation industry.
Then came the "Airline Deregulation Legislation Act of 1978", which lowered fares and increased competition among airlines, making air tickets more affordable.
Finally, the "General Aviation Revitalization Act of 1994", reduced the liability of airline manufacturers and provided a boost to the airline manufacturing industry and an opportunity for small airliner manufacturers. It was an act that added more jobs and promoted the growth of the aviation industry.
The created act during this period to address four factors: safety, infrastructure, price and liability. The chronology of the act creation also represents the importance of each factor, first ensuring aircraft safety, second ensuring the number of airports, then increasing consumption, and finally defining the distribution of liability. Compared to the earlier development-oriented policies established in the airliner market, the policies in the development period have more of a role in defining the framework and establishing the boundaries. Allowing the airliner market to be truly planned and scheduled.
The advanced technology and effective policies of this period also increased the number of passenger aircraft passengers per year in the United States from 60 million in 1962 to nearly 700 million in 2000. The data proves that the U.S. has been successful in the development of the aviation industry.

### Maturity Phase (2000 - Present)

From 2000 onward, the number of passengers carried by airliners in the U.S. each year has shifted to a stage where the growth rate has gradually been maintained at a flat rate. The factors that have had this effect are the advancement of technology in the world, the changing needs of airline passengers, the occurrence of unforeseen events and the impact on the economy.
From a technological standpoint, airliner technology is no longer geared toward engine upgrades, and speed and timeliness are no longer the only criteria. The French Concorde supersonic aircraft is a good example. Airliner technology has shifted from engineering to passenger design, including (cabin amenities upgrades, passenger capacity improvements, aircraft stability design and aircraft comfort design), and these metrics are more focused on the passengers themselves. Making air travel more comfortable became the main airliner design goal after 2000 while increasing passenger capacity based on comfort. Both Boeing and Airbus, the two global monopolies in the aviation industry, have launched the Airbus A380 and Boeing 737-Max models with more comfort and higher passenger capacity.
And comfort and high passenger capacity design still did not stop the decline in annual airliner passenger volume in the United States, mainly due to unforeseen events from outside the aviation industry that was caused by economic factors. From the beginning of 2000 to the present, three significant declines in annual U.S. passenger airline passenger traffic have occurred. These three time periods correspond to,
* 9/11 in 2001, when terrorist events compounded passenger aircraft security factors, resulting in a 36.7% drop in passenger volume compared to 2000.
* The financial crisis in 2007, when the deep dive in the financial markets led to a significant increase in the price of jet fuel and a decrease in travel demand by the American people due to economic reasons.
* The COVID-19 epidemic in 2020, the mass transmission of viruses will require the American people to stay in quarantine for longer periods of time, eliminating all necessary air travel. 2020 passenger aircraft capacity is down more than 60% from 2019, the same level of passenger traffic as in 1985.
These contingencies have largely prevented the continued growth trend of airliners, but they also suggest that the mode of transportation itself is in the crosshairs of these contingencies and that even without them it is difficult not to be certain that passenger aircraft will reduce the growth trend. The 5G fast network era has arrived, and securities and checks mailed by aircraft since 1926 can be transmitted in seconds using the network. Telecommuting and meetings are no longer difficult or complicated, and the development of VR and AR is facilitating more means of virtual interaction. Meanwhile, Asia's fast-growing high-speed rail system is competing with airliner systems for domestic transportation at a cheaper price, in the same amount of time and with better comfort. Airliner transportation systems are encountering increasing challenges. The only continuing advantage is the short-time transoceanic capability they have, and this may be the only reason passengers will choose any airliners in the future.

## Quantitative Analysis-(U.S. Annual Enplaned Airliner Passengers)

By comparing and combining two sets of data from Airlines for America (Data & Statistics/Past A4Annual Reports 1937-2011) and Bureau of Transportation Statistics (2001 - 2022). Historical data on the number of passengers on U.S. airliners per year from 1926 to 2022 was obtained. The entire life cycle (early, development and maturity) of U.S. airliners were statistically analyzed.

### Formula

Three-parameter S-curve logistic function was used :
S(t) = S$_{max}$/[1+exp(-b(t-t$_i$)]
S(t) = State Measurement (in units of individual passengers on board)，
t = time (in years)，
t $_0$ = inflection point time (the year in which half of S max is obtained)，
S $_{max}$ = saturation level (maximum annual passenger capacity of U.S. airliner)，
b = the coefficient to be estimated.

### Parameters

In order to fit the model as closely as possible (R-squared close to 1), different S$_{max}$parameters were used for the tests, and the final S$_{max}$ value was determined by narrowing down the range one at a time from a wide range of tests and a number of tests to determine the true S$_{max}$ boundary.
The final most tested S-Max value is 93606600 numbers of passengers.

#### Regression Results

Model fit of the predicted data obtained using S_Max=93606600
| Variable | Value | Regression Statistics （1926 to 2022) | Regression Statistics （1926 to 2022) | Regression Statistics (1926 to 2019) | Regression Statistics (1926 to 2019) |
| S_max | 936066000 | Multiple R | 0.943978862 | Multiple R | 0.954178 |
| b | 0.109892 | R Square | 0.891096091 | R Square | 0.910455 |
| t_i | 1992.33 | Adjusted R Square | 0.889949734 | Adjusted R Square | 0.909482 |
| | | Standard Error | 1.086944085 | Standard Error | 0.989378 |
| | | Observations | 97 | Observations | 94 |

#### Regression Statistics for 1926 to 2022

The reason R Square did not exceed 0.9 is because the number of passengers on U.S. airliners in 2020 decreased by 60% compared to 2019, which is a very abnormal figure, so the model fit data was calculated using S_Max=93606600 for the forecast data until 2021.

#### Regression Statistics for 1926 to 2019

The R square exceeds 0.9 and reaches 0.91, which makes the forecast data before 2020 more consistent with the model.

### Results

The raw record data is placed in the provided Google Sheets for each year against the middle vacancy obtained by reviewing the annual A4A Annual Reports keyword analysis.
The following excel reperents the "Actual and projected recorded of annual enplaned U.S. airliner passengers from 1926 to 2022".
| YEAR | REAL-PASSENGERS | PREDICT-PASSENGERS | YEAR | REAL-PASSENGERS | PREDICT-PASSENGERS | YEAR | REAL-PASSENGERS | PREDICT-PASSENGERS | YEAR | REAL-PASSENGERS | PREDICT-PASSENGERS |
| 1926 | 5782 | 638825.7 | 1950 | 19099889 | 8850417 | 1974 | 207449000 | 110182444.1 | 1998 | 612900000 | 609304830 |
| 1927 | 8679 | 712973.5 | 1951 | 24685300 | 9867621 | 1975 | 205062000 | 121322154.2 | 1999 | 636000000 | 632274297.5 |
| 1928 | 49713 | 795720.2 | 1952 | 27381801 | 11000348 | 1976 | 223313000 | 133406190.7 | 2000 | 665500000 | 654375604.8 |
| 1929 | 173405 | 888061.4 | 1953 | 31215371 | 12261383 | 1977 | 240326000 | 146477443.9 | 2001 | 622100000 | 675531560 |
| 1930 | 417505 | 991107 | 1954 | 35184000 | 13664841 | 1978 | 274719000 | 160573217.3 | 2002 | 612900000 | 695682302.5 |
| 1931 | 531662 | 1106095 | 1955 | 41623000 | 15226295 | 1979 | 316863000 | 175723569.7 | 2003 | 646300000 | 714785031.6 |
| 1932 | 547560 | 1234407 | 1956 | 45943000 | 16962891 | 1980 | 296749000 | 191949563.7 | 2004 | 702900000 | 732813229.6 |
| 1933 | 576612 | 1377582 | 1957 | 49339000 | 18893487 | 1981 | 285976000 | 209261480.1 | 2005 | 738600000 | 749755479.3 |
| 1934 | 572265 | 1537335 | 1958 | 49075000 | 21038779 | 1982 | 294102000 | 227657069.9 | 2006 | 744700000 | 765613982.5 |
| 1935 | 874116 | 1715581 | 1959 | 55875000 | 23421442 | 1983 | 318638000 | 247119934.6 | 2007 | 769600000 | 780402885.7 |
| 1936 | 1166043 | 1914451 | 1960 | 57700000 | 26066257 | 1984 | 344683000 | 267618134.3 | 2008 | 743300000 | 794146510.9 |
| 1937 | 1289735 | 2136321 | 1961 | 58441000 | 29000242 | 1985 | 380024000 | 289103131.1 | 2009 | 703900000 | 806877573.1 |
| 1938 | 1536111 | 2383838 | 1962 | 62480000 | 32252767 | 1986 | 418946000 | 311509173.4 | 2010 | 720500000 | 818635455.6 |
| 1939 | 2045021 | 2659952 | 1963 | 71414000 | 35855660 | 1987 | 447678000 | 334753216.6 | 2011 | 728368297 | 829464593.5 |
| 1940 | 3185278 | 2967945 | 1964 | 81774000 | 39843283 | 1988 | 454614000 | 358735453.8 | 2012 | 734322469 | 839413001.4 |
| 1941 | 4380610 | 3311474 | 1965 | 94662000 | 44252582 | 1989 | 453692000 | 383340500.7 | 2013 | 740859387 | 848530967.7 |
| 1942 | 3943979 | 3694608 | 1966 | 1.09E+08 | 49123094 | 1990 | 456560000 | 408439240.6 | 2014 | 761003553 | 856869925.1 |
| 1943 | 3891997 | 4121875 | 1967 | 1.32E+08 | 54496906 | 1991 | 412301000 | 433891286.5 | 2015 | 796914123 | 864481496.3 |
| 1944 | 5191225 | 4598309 | 1968 | 1.5E+08 | 60418540 | 1992 | 475108000 | 459547978.2 | 2016 | 822888623 | 871416710.2 |
| 1945 | 8287373 | 5129509 | 1969 | 1.72E+08 | 66934764 | 1993 | 488520000 | 485255783.8 | 2017 | 848769671 | 877725373.7 |
| 1946 | 13254728 | 5721698 | 1970 | 1.7E+08 | 74094304 | 1994 | 528848000 | 510859945.3 | 2018 | 888629905 | 883455586.7 |
| 1947 | 14249920 | 6381784 | 1971 | 1.74E+08 | 81947445 | 1995 | 547384000 | 536208186.8 | 2019 | 926436914 | 888653380.8 |
| 1948 | 14540854 | 7117439 | 1972 | 1.91E+08 | 90545494 | 1996 | 581200000 | 561154297 | 2020 | 369691837 | 893362466.6 |
| 1949 | 16600771 | 7937172 | 1973 | 2.02E+08 | 99940108 | 1997 | 599100000 | 585561409.3 | 2021 | 666147623 | 897624072.2 |
| | | | | | | | | | 2022 | 780674848 | 901476856.5 |

#### Data Visualization

The analysis of the simulated data curves provides good evidence that the overall prediction fit is consistent with the actual data.
Also, the three phases above, early (1926-1960), development (1960-2000), and maturity (2000-2022) all fit the magnitude of change in the predicted curve.
The only difficulty is that it is more challenging to perform a higher-fit analysis on the 97-year data, and the forecast curve obtained in this paper is still only a close approximation to the true forecast curve, which needs to be more subdivided according to the degree of data variation.
BLUE LINE- Predict Enplaned Passengers GREEN LINE- Actual Enplaned Passengers

##### 2000-2022 (Maturity)
## References

* 1 2 3 (@AIRBUS A380 AIRCRAFT CHARACTERISTICS AIRPORT and MAINTENANCE PLANNING AC, n.d.)
* ↑ Climate change and flying: what share of global CO2 emissions come from aviation? n.d., Our World in Data.
* 1 2 3 4 5 The Evolution of the Commercial Airliner n.d., airandspace.si.edu.
* 1 2 3 4 5 6 7 8 9 10 11 12 History of flight - The first airlines n.d., Encyclopedia Britannica.
* 1 2 Boeing: Boeing History n.d., www.boeing.com.
* ↑ Boon, T & Memon, DO 2022, Quadjet Decline: The Passenger Airlines That Retired Boeing 747s & Airbus A380s In 2022, Simple Flying, viewed 12 March 2023
* ↑ 未来20年全球将交付44,500架新飞机，价值高达2.9万亿美元 2023, www.businesswire.com, viewed 12 March 2023,
* 1 2 Maps of the day: Travel times from NYC in 1800, 1830, 1857 and 1930 2016, American Enterprise Institute - AEI.
* ↑ Halpern, MC and S 2007, ‘Olympic and Titanic : Maiden Voyage Mysteries’, Encyclopedia Titanica, viewed 12 March 2023
* ↑ 1903 Wright Flyer | National Air and Space Museum n.d.
* ↑ 1918 Curtiss JN-4D ‘Jenny’ n.d., www.eaa.org, viewed 12 March 2023
* ↑ Air Mail and the Birth of Commercial Aviation 2021, airandspace.si.edu.
* ↑ Boeing 247 2021, Wikipedia.
* ↑ Airmail Act of 1930. (n.d.). Avstop.com.
* 1 2 3 4 5 6 7 Past A4A Annual Reports (1937-2011) n.d., Airlines For America.
* ↑ Civil Aeronautics Act of 1938 n.d., avstop.com.
* ↑ Boeing 307 Stratoliner 2020, Wikipedia.
* ↑ Federal Aviation Act Of 1958 n.d., avstop.com.
* ↑ Airport and Airway Development Act of 1970 n.d., avstop.com.
* ↑ Airline Deregulation Legislation Act 1978 n.d., avstop.com.
* ↑ General Aviation Revitalization Act 1994 n.d., avstop.com.
* 1 2 3 Data Elements. (2012). Bts.gov. viewed 09 March 2023.
* ↑ Clark, David E., 等. 《The Effects of 9/11 on the Airline Travel Industry》. The Impact of 9/11 on Business and Economics: The Business of Terror, 编辑 Matthew J. Morgan, Palgrave Macmillan US, 2009, 页 75–86. Springer Link
* ↑ Segal2018-09-07T12:56:55+01:00, S n.d., ANALYSIS: What the Great Recession meant for aircraft funding, Flight Global, viewed 12 March 2023.