To the untrained eye, the three aircraft pictured below might look like they are the exact same type. Unless you are a serious aviation enthusiast, you probably can’t tell the difference between them at first glance. If you have ever wondered what the differences are between the Douglas DC-9, McDonnell Douglas MD-80, and the Boeing 717, then keep reading. But first, see if you can guess which aircraft is which.
If you guessed the top was a DC-9, the middle a B717, and the bottom an MD-80, you were right. The truth is that all these aircraft were based off the Douglas DC-9, and together are considered the “DC-9 Family.”
A brief history…
The first of the type, the Douglas DC-9, was first introduced into service with Delta Airlines in 1965. It was developed by the Douglas Aircraft Company for airlines to use on short but frequent routes. Its main feature was its ability to utilize short runways, which allowed for the introduction of jet service to smaller airports that previously only saw propeller driven aircraft. Over 900 of the type were produced with the last delivery in 1982. Today, the main operators of the aircraft are Delta Airlines and USA Jet. They are slowly being phased out of fleets and will probably be nonexistent within the next couple of years.
The next generation of the aircraft was originally supposed to be designated the DC-9-80 “Super 80.” However, after Douglas merged with McDonnell Aircraft, its name was changed to the McDonnell-Douglas MD-80. The MD-80, and the later MD-90 variation, were much larger than the DC-9 they were based off of. The first of the type entered service with Swissair and Austrian Airlines in 1980. About 1,000 aircraft were produced in total, making it the most popular aircraft of the DC-9 Family. The largest operators of the type are American Airlines and Delta Airlines with about 200 and 100 aircraft respectively.
The most recent of the DC-9 Family is the Boeing 717. 156 of the type were produced in total, making it the least popular of the series. The last 2 of the type were delivered in 2006 to Air Tran and Midwest Airlines, marking the end of one of the most historic and popular aircraft series the world has ever seen. Just like the MD-80, the 717’s name came from a company merger. This time, the McDonnell-Douglas aircraft corporation was absorbed by Boeing Commercial Airplanes in 1997. The main improvement of the 717 over previous types is the state of the art, modern flight deck. It features 6 interchangeable LCD Displays and advanced computers. The largest operator of the type by far is AirTran. As the airline is absorbed into Southwest Airlines, the 717s will be transferred to Delta. This means that starting next year, Delta will operate all 3 types of the DC-9 Family.
How to tell the difference…
So now that you know how each variation of the DC-9 Family came to exist, you probably want to know how you can actually tell the 3 apart. Each variant has a few unique characteristics, both inside and out.
The DC-9 has much smaller engines than the other two. It also features a pointier tail cone. On the other hand, the 717 has large, bulky, powerful engines with a more rounded tail cone. The MD-88 combines the characteristics of the DC-9 and B717, which makes sense as it served as a transition between the two.
The best way to distinguish an MD-80 from the other 2, is that it is much longer with much wider wings. DC-9’s and 717’s are about 124 feet long, depending on the specific variant, with a wingspan of 93 feet. The MD-88 is an impressive 148 feet long with a 108 foot wingspan.
For people with a decent amount of knowledge about commercial aviation, the easiest way to tell the difference is by what airline is operating it. For example, American Airlines only operates the MD-80 and AirTran now only operates the Boeing 717. As you become more involved in the aircraft spotting hobby, you quickly learn which airlines operate which types of aircraft. Delta, on the other hand, will soon operate the DC-9, MD-80, and 717. (So much for that method…)
From the inside you can sometimes tell the difference by the seating layout. Delta’s MD-80’s have 3 seats on the left side of the aisle and 2 on the right, while its DC-9’s are the other way around. The 717’s cockpit is very unique and recognizable as compared to the other two.
Next time you find yourself at an airport, try to see if you can figure out which is which.