February 25, 1965 marks the first flight of the Douglas DC-9. The DC-9 ("DC" stands for "Douglas Commercial") and its variants would go on to become one of the most popular short- to medium-range airliners in the world. The DC-9 is a single aisle, twin-engine airliner designed for frequent, short flights, and was delivered to its first customer, Delta Air Lines, in December 1965. Continuous development of the DC-9 resulted in the MD-80 series, MD-90 series, and the Boeing 717, after the McDonnell Douglas and Boeing merged in 1997. The DC-9 family of aircraft were remarkably successful, ranking third in the total number of aircraft produced behind the Boeing 737 (over 8000 produced) and the Airbus 320 family (over 6000 produced). Production ended in 2006 after 41 years with the final 717 delivered to AirTran Airlines. A total of 2,400 units had been built.


Southern Airways DC-9-10

The initial production version of the DC-9-10 was powered by a pair of Pratt & Whitney JT8D turbofans and seated 90 passengers in a one class configuration. The -30, -40 and -50 variants saw passenger capacities increase to 115, 125, and 139 passengers respectively. The maximum takeoff weight (MTOW) of 82,000 lbs for the -10 was steadily increased to 121,000 lbs for the -50.

Iberia Airlines MD-88

The MD-80, originally called the DC-9-80, featured a lengthened fuselage, a higher MTOW, a larger wing, new main landing gear and a higher fuel capacity. A pinch tail replaced the tail cone to reduce drag. It used an improved Pratt & Whitney JT8D turbofan engine which provided higher thrust ratings than the earlier DC-9 series.


Japan Airlines MD-90

The MD-90 saw a further lengthening of the fuselage, the addition of a glass cockpit, and new International Aero V2500 high-bypass turbofan engines which produced a higher speed and extended range.


AirTran Boeing 717-200

The final variant was the MD-95, which was renamed the Boeing 717-200. Its fuselage and wing are similar to the shorter DC-9-30, but makes use of lighter modern materials. It's power comes from two BMW/Rolls-Royce BR715 high-bypass turbofans.


The DC-9 was also flown by the US military with the designation C-9. It was produced as the C-9A Nightingale for the Air Force, and the C-9B Skytrain II for the Navy and Marine Corps.


US Air Force C-9A Nightingale

So, how to tell the civilian versions apart in the wild? Here's a simple spotter's guide.

  • DC-9: Short fuselage, no strakes under the cockpit, pointy tail. (The last DC-9 variant, the DC-9-50, was equipped with strakes, but it retained the cone-shaped tail.)
  • MD-80 series: Longer fuselage, strakes under the cockpit, pinch tail, skinny engines.
  • MD-90 series: Longer fuselage, strakes under the cockpit, pinch tail, fat engines.
  • B717: Shorter body, no strakes under the cockpit, pinch tail, fat engines.

Basically, you can tell the DC-9-10/20/30/40 from the 717 by the tail cone, and the MD-80 series from the MD-90 series by the size of the engines.

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