Dhaka: Plenty of factors including size, energy efficiency, cargo and passenger load, comfort and cost are involved in making a plane design appealing to airlines and their customers. Hence, it is not easy to be among the best-selling civil airplanes of all time. Let us take a look at the top five, based on total deliveries as of December 31, 2021, to see how these planes stood out the most.

5. Boeing 727

This mid-sized plane, with a T-shaped tail and three rear-mounted engines, was in production from 1962 to 1984 with 1,832 deliveries in its name. It had range for transoceanic flights but was also versatile enough to land on short runways at smaller airports.

Boeing's original plan was to build just 250 of the craft, but it would go on to be the first commercial airplane to reach the 1,000-sales milestone.

4. Bombardier CRJ

Regional jets are smaller planes, usually with fewer than 100 seats, that are designed for short-haul routes. The Bombardier Canadair Regional Jet family is the best-selling of its kind. It was in production since 1991 to 2020 with 1,945 deliveries.

Canadian manufacturer Bombardier launched the programme with the 50-seat CRJ, which was certified in 1992, before expanding with the 70-seat CRJ700 in 1997, the 86-seat CRJ900 in 2000 and the 100-seat CRJ1000 in 2007.

The last of the popular short-hop jets was delivered to Utah-based SkyWest Airlines in February 2021.

3. Airbus A320

Airbus delivered its 10,000^th A320 in the summer of 2021 and, if this list was based on orders as well as deliveries, the A320 overtook the Boeing 737 as the 21st century's most popular plane back in 2019. It has been in production since 1986 to present with 10,176 deliveries so far.

The first A320 entered service in March 1988 and the twin-engine single-aisle craft has clocked up over 280 million flight hours in the years since.

Variants include the A318, A319 and A321, while the A320neo family was introduced into service in 2016.

2. Boeing 737

The Boeing 737 is one of the aviation stalwarts, another being A320. It has been in production since 1968 to present with 10,877 deliveries so far.

The narrow-body classic has been traversing the skies for over half a century, and the improved Next-Generation civilian version was produced from 1996 to 2019.

1. Cessna 172

While the 737 and A320 are the world's top passenger aircraft, the plucky little four-seater Cessna 172 is the most successful civil aircraft in history, with more than 45,000 deliveries so far since its production in 1968.

Its primary use is as a training plane, and generation after generation of pilots have cut their teeth in them. The high wings on this single-engine craft give pilots better visibility, making it easier to get their bearings on the world around them and also to land.

The large cabin doors make it simple for trainees and instructor to hop in and out, meaning that this is a popular design classic that has endured.