The Airbus A321 and Boeing 737 are competing narrow-body twinjet aircraft. The 737 was introduced 27 years before the first A321 started operating.
That said, the 737 has continued to evolve and improve over the decades and is still in production with plenty of orders for the 737MAX variants still to be delivered. The A321 is part of the highly successful A320 family of Airbus aircraft and also has a significant orders backlog for the A32neo variant.
In this article, I’ll chart the histories of these two similar aircraft, and see how they measure up against each other.
History
The flying history of the 737 goes all the way back to 1967 and can be described as a constant evolution. The 737 delivery run has, so far, lasted for 55 years and will continue well into this decade with significant orders still to be completed for the 737MAX.
The 737 family has been developed over four separate series (or generations), the earlier two of which are no longer in production:
- Boeing 737 Original comprises two main variants – the 737-100 and the 737-200. More than one thousand 737 Originals were delivered by Boeing.
- Boeing 737 Classic comprises three more fuel-efficient variants with differing capacities and ranges: the 737-300, the 737-400, and the 737-500. Almost two thousand 737 Classics were delivered by Boeing.
- Boeing 737 Next Generation (NG) comprises four main variants: the 737-600, the 737-700 (and 737-700ER), the 737-800, and the 737-900 (and 737-900ER). More than six thousand 737NG aircraft were delivered by Boeing.
- Boeing 737MAX is an evolution of earlier 737 generations, with more efficient engines, aerodynamic improvements such as distinctive split-tip winglets, as well as airframe modifications. The 737MAX series has four variants: MAX7, MAX8, MAX9, and MAX10.
The majority of Boeing’s 737 production is now focused on the 737MAX, with only a small number of 737-800s, and the specialist 737-800A, aircraft yet to be delivered from the NG series.
Series | Models Included | First in Service | Last Delivery |
Original | 737-100, 737-200 | 1967 | 1988 |
Classic | 737-300, 737-400, 737-500 | 1984 | 2000 |
Next Generation | 737-600, 737-700, 737-800, 737-900 | 1997 | In production (737-800/800A only) |
MAX | 737MAX7, 737MAX8, 737MAX9, 737MAX10 | 2017 | In production (737MAX10 from 2023 onwards) |
The A321 is part of the A320 narrow-body twinjet family. It first flew commercially in 1994 as the A321-100 but was quickly followed in 1997 by the A321-200. The A321-200 came with an increased fuel tank capacity, maximum take-off weight, and range.
The A321neo (new engine option) variant first flew commercially in 2017. With more efficient engines and other efficiency improvements, including wing sharklets, the A321neo provides improved fuel economy, longer ranges, and additional payload compared to older variants. The neo engines – CFM International’s LEAP-1A and Pratt & Whitney’s PurePower PW1100G-JM geared turbofans – are also quieter, improving travel comfort in the aircraft cabin.
With the introduction of the neo variants, older A321 versions became known as the A320ceo (current engine option).
The longer-range A321LR first started flying commercially in 2018 and offers a range of up to 4,000nm Production and testing of the A321XLR (extra-long range) are in process, but Airbus recently announced that the first deliveries would not now take place until 2024: “On the A321XLR, the Company continues to work towards a first flight by the end of Q2 2022. Initially planned for the end of 2023, the entry-into-service is now expected to take place in early 2024 in order to meet certification requirements.”
The A321XLR is expected to feature 15% more range than the A321LR. Airlines are showing strong interest in the XLR – Airbus has received sizable orders from a variety of carriers, including American Airlines, Delta Air Lines, IndiGo, Wizz Air, and Qantas.
Aircraft Model | First In Service |
A321-100ceo | 1994 |
A321-200ceo | 1997 |
A321neo | 2017 |
A321LR | 2018 |
A321XLR | 2024 (est.) |
Dimensions
Let’s take a look at some key physical characteristics and see how these two aircraft measure up against each other.
The A321 variants have a common set of dimensions but have varying MTOWs:
Aircraft Model | Length/m | Wingspan/m | Tail Height/m | Fuselage Width/m | MTOW/ tonnes |
A321ceo | 44.51 | 35.80 | 11.76 | 3.95 | 93.50 |
A321neo (LR) | 97.00 | ||||
A321XLR | 101.00 |
The numerous 737 variants demonstrate quite a lot of variety in terms of size and physical characteristics.
For example, if we look at how the fuselage length of the 737 variants has changed over time, we see that there has been a tendency for the 737 to increase in length as new variants are rolled out, although the relationship is not perfect as some variants such as the 737-500, 737-600, and 737-700 were purposely developed with relatively short fuselages.
All 737 variants have shorter fuselages than the A321.
The shortest 737 was the original 737-100 at 29m, and the longest will be the 737MAX10 at almost 44m. The 737 wingspan has varied from around 28m to 36m. The 737 fuselage width has remained constant throughout at around 3.8m, slightly narrower than the A321.
Let’s look in more detail at the 737MAX:
Aircraft Model | Length/m | Wingspan/m | Tail Height/m | Fuselage Width/m | MTOW/ tonnes |
737MAX7 | 35.6 | 35.9 | 12.3 | 3.76 | 80.0 |
737MAX8 | 39.5 | 82.6 | |||
737MAX9 | 42.2 | 88.3 | |||
737MAX10 | 43.8 | 89.8 |
Range
The A321ceo range is around 3,200nm, whereas the A321neo offers a slightly longer range of 4,000nm, thanks to its LR variant. The game-changing A321XLR will offer a further extended range of 4,700nm. With a maximum flying time of 11 hours, the A321XLR will be suited to a wide range of routes not previously possible with narrowbody aircraft.
All A321 variants are ETOPS (Extended-range Twin-engine Operational Performance Standards) certified for 180 minutes since 2004 (EASA) and 2006 (FAA).
Aircraft Model | Range |
A321ceo | 5,950km/3,200nm with sharklets |
A321neo | 6,850km/3,700nm |
A321LR | 7,400km/4,000nm |
A321XLR | 8,700km/4,700nm |
The A321 variants have ranges varying between 3,200nm (A321ceo) and 4,700nm(A321XLR). The A321XLR range is significantly longer than the ranges achieved by all 737MAX aircraft. All of the 737 variants are primarily designed for short- to medium-haul routes. However, some 737 aircraft, especially later variants, are also 180-minutes ETOPS certified. But, ETOPS-certified 737s rarely fly on transatlantic routes.
The 737 variant ranges vary significantly, and so not to complicate matters too much, let’s take a look at the variants within the 737NG and 737MAX series with the longest and shortest ranges as shown in the tables below, starting with the longest ranges:
Series | Model | Range |
737NG | 737-600 | 3,235nm (5,991km) |
737MAX | 737MAX7 | 3,850nm (7,130km) |
The relatively rare 737-600 has the longest range of the 737NG models.
Below are the 737 variants with the shortest ranges:
Series | Model | Range |
737NG | 737-800 | 2,935nm (5,436km) |
737MAX | 737MAX10 | 3,300nm (6,110km) |
Seating Capacity and Configurations
Airbus’ typical 2-class and maximum seating capacities for the A321 variants are shown in the table below:
Aircraft | Typical 2-Class Seating Capacity | Maximum Seating Capacity |
A321ceo | 170 – 210 | 220 |
A321neo/XLR | 180 – 220 | 244 |
In practice, we see a variety around these numbers as airlines have fitted out these aircraft in 1-class, 2-class, 3-class, and even 4-class configurations. In some premium cabins, there are lie-flat seats which reduce overall seat density.
Looking at a variety of airlines operating A321 aircraft (Air Asia, American Airlines, British Airways, Cebu Pacific, easyjet, Frontier Airlines, Indigo, JetBlue, Lufthansa, Spirit Airlines, Starlux, Vistara, Wizz Air), actual fitted-out seat numbers typically vary as follows:
Aircraft | 1-class | 2-class | 3-class | 4-class |
A321 | 200 – 239 | 154 – 240 | 138 – 196 | 102* |
*American Airlines A321-200 V1 (First Class – 10, Business Class – 20, Premium Economy Class (Main Cabin Extra) -36, Economy Class – 36)
Boeing’s suggested seating numbers for the 737MAX are as follows:
737MAX7 | 737MAX8 | 737MAX9 | 737MAX10 | |
Seats (2-class) | 138 – 153 | 162 – 178 | 178 – 193 | 188 – 204 |
Maximum seats | 172 | 210 | 220 | 230 |
Looking at a variety of airlines operating 737MAX8 and 737MAX9 aircraft (AeroMexico, Air Canada, American Airlines, Alaska Airlines, China Southern, Copa Airlines, Ethiopian Airlines, FlyDubai, Fiji Airways, Garuda Indonesia, Icelandair, Korean Air, LOT, Norwegian, Oman Air, Ryanair, Singapore Airlines, Spicejet, Southwest, Turkish Airlines, and United Airlines), actual fitted-out seat numbers typically vary as follows:
Aircraft | 1-class | 2-class | 3-class |
737MAX8 | 175 – 197 | 146 – 178 | 166 – 178 |
737MAX9 | – | 172 – 179 | 166 – 181 |
Aircraft Orders
As of the end of December 2022, a total of 6,400 A321 aircraft have been ordered, of which 2,715 (42%) have been delivered. This means that Airbus has a significant backlog of A321neo orders yet to be delivered, with only around 20% of A321neo orders delivered to date.
The graph below shows the number of orders and deliveries for the A321ceo and the A321neo to the end of December 2022:
As of the end of December 2022, the top 3 customers for each A321 variant are as follows:
Top 3 Customers | A321ceo Orders |
Delta Airlines | 127 |
US Airways | 121 |
ILFC | 91 |
Top 3 Customers | A321neo Orders |
Indigo | 386 |
AirAsia | 366 |
Wizz Air | 359 |
‘Low cost’ airlines are very significant A321 customers, taking the top three spots for the number of A321neo orders.
I looked at Boeing’s official data to the end of December 2022 to investigate how many 737s have been ordered and delivered for each variant. I grouped the data into generations and this is what I found:
*The 737NG and 737MAX ‘deliveries’ in the graph above are the sum of delivered aircraft and unfulfilled orders to provide a ‘like-for-like’ comparison with other variants.
The graph above shows that the Next Generation is the most successful of the four 737 generations to date. In terms of individual variants, the 737-800 and the 737MAX are the two most successful.
Boeing has delivered around 19% of its 737MAX orders, and recently the company announced that it plans to increase production of the 737MAX, from 31 planes a month to about 50 by 2025. Boeing executives previously pointed to supply chain bottlenecks as the major driver for lagging 737 MAX production.
The 737 has received 2.3 times the orders of the A321. However, that’s not that surprising; the 737 has been around a lot longer than the A321. Also, Airbus offers other narrowbodies that compete with the 737. If all of the A318, A319, A320, and A321 orders are added together (almost 16,800) this total exceeds the total number of 737 orders.
A321 vs. 737: Summary
The A321 and the newer 737 variants are relatively similar aircraft; both are narrowbody twinjet aircraft. The 737 NextGen variants and the A321 are 180-minute ETOPS certified allowing them to operate on long-distance over-water routes traditionally operated by 4-engined widebody aircraft. However, 737 transatlantic routes remain a rarity, whereas the A321LR is becoming an increasingly regular sight on services between Europe and the USA.
The 737 is a constantly evolving aircraft that has been in production for more than five decades. The 737’s evolution has often occurred under competitive pressure from other manufacturers, particularly Airbus and its A320 family. Significant numbers of 737 aircraft continue to be produced, and the constant improvements to the 737 have given this aircraft a new lease of life with its NG and MAX series.
Despite its popularity with airline customers, the 737 has not been without controversy. The 737MAX air crashes in 2018 and 2019 seriously dented customer confidence in the MAX program and in Boeing. Boeing is now starting to recover from this with the majority of aviation authorities having now cleared the 737MAX to return to the skies.
Significant numbers of A321 aircraft continue to be produced by Airbus, and the A321LR and A321XLR have given this aircraft type a new lease of life, allowing airlines to deploy this versatile aircraft on new routes.
With many orders yet to be fulfilled, it looks like both the A321neo and the 737MAX variants will be gracing our skies for decades to come.