McDonnell Douglas DC-9

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DC-9
New York Air DC-9 Detroit - 16 August 1983.jpg
A New York Air DC-9-32, 1983
RoleNarrow-body jet airliner
ManufacturerDouglas Aircraft
McDonnell Douglas
First flightFebruary 25, 1965
IntroductionDecember 8, 1965 with Delta Air Lines
StatusIn limited use
Primary usersUSA Jet Airlines
Everts Air Cargo
Northwest Airlines (historical)
Delta Air Lines (historical)
Produced1965–1982
Number built976
Unit cost
US$41.5 to $48.5 million
VariantsMcDonnell Douglas C-9
Developed intoMcDonnell Douglas MD-80
McDonnell Douglas MD-90
Boeing 717
 
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DC-9
New York Air DC-9 Detroit - 16 August 1983.jpg
A New York Air DC-9-32, 1983
RoleNarrow-body jet airliner
ManufacturerDouglas Aircraft
McDonnell Douglas
First flightFebruary 25, 1965
IntroductionDecember 8, 1965 with Delta Air Lines
StatusIn limited use
Primary usersUSA Jet Airlines
Everts Air Cargo
Northwest Airlines (historical)
Delta Air Lines (historical)
Produced1965–1982
Number built976
Unit cost
US$41.5 to $48.5 million
VariantsMcDonnell Douglas C-9
Developed intoMcDonnell Douglas MD-80
McDonnell Douglas MD-90
Boeing 717

The McDonnell Douglas DC-9 (initially known as the Douglas DC-9) is a twin-engine, single-aisle jet airliner. It was first manufactured in 1965 with its maiden flight later that year. The DC-9 was designed for frequent, short flights. The final DC-9 was delivered in October 1982.

The DC-9-based airliners, MD-80, MD-90 and Boeing 717 later followed in production. With the final deliveries of the 717 in 2006, production of the DC-9/MD-80/90/717 aircraft family ceased after 41 years and over 2,400 units built.

Design and development[edit]

Origins[edit]

During the 1950s Douglas Aircraft studied a short- to medium-range airliner to complement their higher capacity, long range DC-8. (DC stands for Douglas Commercial.[1]) A medium-range four-engine Model 2067 was studied but it did not receive enough interest from airlines and it was abandoned. In 1960, Douglas signed a two-year contract with Sud Aviation for technical cooperation. Douglas would market and support the Sud Aviation Caravelle and produce a licensed version if airlines ordered large numbers. None were ordered and Douglas returned to its design studies after the cooperation deal expired.[2]

In 1962, design studies were underway. The first version seated 63 passengers and had a gross weight of 69,000 lb (31,300 kg). This design was changed into what would be initial DC-9 variant.[2] Douglas gave approval to produce the DC-9 on April 8, 1963.[2] Unlike the competing but larger Boeing 727 trijet, which used as many 707 components as possible, the DC-9 was an all-new design. The DC-9 has two rear-mounted Pratt & Whitney JT8D turbofan engines, relatively small, efficient wings, and a T-tail.[3] The DC-9's takeoff weight was limited to 80,000 lb (36,300 kg) for a two-person flight crew by Federal Aviation Agency regulations at the time.[2] DC-9 aircraft have five seats across for economy seating. The airplane seats 80 to 135 passengers depending on version and seating arrangement.

The DC-9 was designed for short to medium routes, often to smaller airports with shorter runways and less ground infrastructure than the major airports being served by larger designs like the Boeing 707 and Douglas DC-8. Accessibility and short field characteristics were called for. The tail-mounted engine design facilitated a clean wing without engine pods, which had numerous advantages. For example, flaps could be longer, unimpeded by pods on the leading edge and engine blast concerns on the trailing edge. This simplified design improved airflow at low speeds and enabled lower takeoff and approach speeds, thus lowering field length requirements and keeping wing structure light.

The second advantage of the tail-mounted engines was the reduction in foreign object damage from ingested debris from runways and aprons. Third, the absence of engines in underslung pods allowed a reduction in ground clearance, making the aircraft more accessible to baggage handlers and passengers. Turnarounds were simplified by built-in airstairs, including one in the tail, which shortened boarding and deplaning times. The problem of deep stalling, revealed by the loss of the BAC One-Eleven prototype in 1963, was overcome through various changes, including the introduction of vortilons, small surfaces beneath the wing's leading edge used to control airflow and increase low speed lift.[4]

Into production[edit]

C-9 Nightingale used for Aeromedical Evacuation

The first DC-9, a production model, flew on February 25, 1965.[5] The second DC-9 flew a few weeks later,[3] with a test fleet of five aircraft flying by July. This allowed the initial Series 10 to gain airworthiness certification on November 23, 1965, and to enter service with Delta Air Lines on December 8.[5] The DC-9 was always intended to be available in multiple versions to suit customer requirements,[6] The first stretched version, the Series 30, with a longer fuselage and extended wing tips, flew on August 1, 1966, entering service with Eastern Air Lines in 1967.[5] The initial Series 10 would be followed by the improved -20, -30, and -40 variants. The final DC-9 series was the -50, which first flew in 1974.[3]

A Cebu Pacific DC-9 in 2006

The DC-9 was a commercial success with 976 built when production ended in 1982.[3] The DC-9 is one of the longest-lasting aircraft in operation. Its reliability and efficiency led to sales of its successors into the 21st century.[citation needed] The DC-9 family is one of the most successful jet airliners with a total of over 2,400 units produced; it ranks third behind the second-place Airbus A320 family with over 5,000 produced, and the first-place Boeing 737 with over 7,000 produced.

Studies aimed at further improving DC-9 fuel efficiency, by means of retrofitted wingtips of various types, were undertaken by McDonnell Douglas. However, these did not demonstrate significant benefits, especially with existing fleets shrinking. The wing design makes retrofitting difficult.[7]

Legacy[edit]

The DC-9 was followed by the introduction of the MD-80 series in 1980. The MD-80 series was originally called DC-9-80 series. It was a lengthened DC-9-50 with a higher maximum takeoff weight (MTOW), a larger wing, new main landing gear, and higher fuel capacity. The MD-80 series features a number of variants of the Pratt & Whitney JT8D turbofan engine having higher thrust ratings than those available on the DC-9.

The MD-80 series was further developed into the McDonnell Douglas MD-90 in the early 1990s. It has yet another fuselage stretch, a glass cockpit (first introduced on the MD-88) and completely new International Aero V2500 high-bypass turbofan engines. In comparison to the very successful MD-80, relatively few MD-90s were built.

The final variant was the MD-95, which was renamed the Boeing 717-200 after McDonnell Douglas's merger with Boeing in 1997 and before aircraft deliveries began. The fuselage length and wing are very similar to those of the DC-9-30, but much use was made of lighter, modern materials. Power is supplied by two BMW/Rolls-Royce BR715 high-bypass turbofan engines.

China's Comac ARJ21 is derived from the DC-9 family. The ARJ21 is built with manufacturing tooling from the MD-90 Trunkliner program. As a consequence, it has the same fuselage cross-section, nose profile, and tail.[8]

Variants[edit]

Series 10[edit]

The original DC-9 (later designated the Series 10) was the smallest DC-9 variant. The -10 was 104.4 ft (31.8 m) long and had a maximum weight of 82,000 lb (37,000 kg). The Series 10 was similar in size and configuration to the BAC One-Eleven and featured a T-tail and rear mounted engines. Power was provided by a pair of 12,500 lbf (56 kN) Pratt & Whitney JT8D-5 or 14,000 lbf (62 kN) JT8D-7 engines. A total of 137 were built. Delta Air Lines was the initial operator.

The Series 10 was produced in two main subvariants, the Series 14 and 15, although, of the first four aircraft, three were built as Series 11s and one as Series 12. These were later converted to Series 14 standard. No Series 13 was produced. A passenger/cargo version of the aircraft with a 136 x 81 in side cargo door forward of the wing and a reinforced cabin floor, was certificated on March 1, 1967. Cargo versions included the Series 15MC (Minimum Change) with folding seats that can be carried at the rear of the aircraft, and the Series 15RC (Rapid Change) with seats removable on pallets. These differences disappeared over the years as new interiors have been installed.[9][10]

The Series 10 was unique in the DC-9 family in not having leading edge slats. The Series 10 was designed to have short takeoff and landing distances without the use of leading edge high-lift devices. Therefore, the wing design of the Series 10 featured airfoils with extremely high maximum lift capability in order to obtain the low stalling speeds necessary for short field performance.[11]

Series 10 features[edit]

The Series 10 has an overall length of 104.4 feet (31.82 m), a fuselage length of 92.1 feet (28.07 m), a passenger cabin length of 60 feet (18.29 m), and a wingspan of 89.4 feet (27.25 m).

The Series 10 was offered with the 14,000 lbf (62 kN) thrust JT8D-1 and JT8D-7.[9][10]

All versions of the DC-9 are equipped with an AlliedSignal (Garrett) GTCP85 APU, located in the aft fuselage.[9][10]

The Series 14 was originally certificated at an MTOW of 85,700 lb (38,900 kg) but subsequent options offered increases to 86,300 and 90,700 lb (41,100 kg). The aircraft's MLW in all cases is 81,700 lb (37,100 kg). The Series 14 has a fuel capacity of 3,693 US gallons (with the 907 US gal centre section fuel). The Series 15, certificated on January 21, 1966, is physically identical to the Series 14 but has the increased MTOW of 90,700 lb (41,100 kg). Typical range with 50 passengers and baggage is 950 nmi (1,760 km), increasing to 1,278 nmi (2,367 km) at long range cruise. Range with maximum payload is 600 nmi (1,100 km), increasing to 1,450 nmi (2,690 km) with full fuel.[9][10]

The DC-9 Series 10, as with all later versions of the DC-9 is equipped with a two crew analog flightdeck.[9][10]

The aircraft is fitted with a passenger door in the port forward fuselage, and a service door/emergency exit is installed opposite. An airstair installed below the front passenger door was available as an option as was an airstair in the tailcone. This also doubled as an emergency exit. Available with either two or four overwing exits, the DC-9-10 can seat up to a maximum certified exit limit of 109 passengers. Typical all-economy layout is 90 passengers, and 72 passengers in a more typical mixed-class layout with 12 first and 60 economy-class passengers.[9][10]

All versions of the DC-9 are equipped with a tricycle undercarriage, featuring a twin nose unit and twin main units.[9][10]

Series 20[edit]

The Series 20 was designed to satisfy a Scandinavian Airlines request for improved short field performance by using the more powerful engines and improved wings of the -30 combined with the shorter fuselage used in the -10. Ten Series 20 aircraft were produced, all of them Model -21.[12]

In 1969, a DC-9 Series 20 at Long Beach was fitted with an Elliott Flight Automation Head-up display by McDonnell Douglas and used for successful three month-long trials with pilots from various airlines, the Federal Aviation Administration, and the US Air Force.[13]

Series 20 features[edit]

The Series 20 has an overall length of 104.4 feet (31.82 m), a fuselage length of 92.1 feet (28.07 m), a passenger cabin length of 60 feet (18.29 m), and a wingspan of 93.3 feet (28.44 m).[9][10]

The DC-9 Series 20 is powered by the 15,000 lbf (67 kN) thrust JT8D-11 engine.[9][10]

The Series 20 was originally certificated at an MTOW of 94,500 lb (42,900 kg) but this was increased to 98,000 lb (44,000 kg), some 8 percent up on the higher weight Series 14s and 15s. The aircraft's MLW is 95,300 lb (43,200 kg) and MZFW is 84,000 lb (38,000 kg). Typical range with maximum payload is 1,000 nmi (1,900 km), increasing to 1,450 nmi (2,690 km) with maximum fuel. The Series 20, using the same wing as the Series 30, 40 and 50, has a slightly lower basic fuel capacity than the Series 10 (3,679 US gallons).[9][10]

Series 20 milestones[edit]

Series 30[edit]

Ex-Spirit Airlines DC-9-30 Firebird II, highly modified as a surveillance aircraft for the U.S. Navy, based at Mojave Airport

The Series 30 was produced to counter Boeing's 737 twinjet; 662 were built, about 60% of the total. The -30 entered service with Eastern Airlines in February 1967 with a 14 ft 9 in (4.50 m) fuselage stretch, wingspan increased by just over 3 ft (0.9 m) and full-span leading edge slats, improving takeoff and landing performance. Maximum takeoff weight was typically 110,000 lb (50,000 kg). Engines for Models -31, -32, -33, and -34 included the P&W JT8D-7 and JT8D-9 rated at 14,500 lbf (64 kN) of thrust, or JT8D-11 with 15,000 lbf (67 kN).

Unlike the -10, the Series 30 had leading edge devices to reduce the landing speeds at higher landing weights; full-span slats reduced approach speeds by 6 knots despite 5000 lbs greater weight. The slats were lighter than slotted Krueger flaps, since the structure associated with the slat is a more efficient torque box than the structure associated with the slotted Krueger. The wing had a six percent increase in chord, all ahead of the front spar, allowing the 15 percent chord slat to be incorporated.[14]

Series 30 versions[edit]

TAA DC-9-30 at Melbourne Airport, 1987

The Series 30 was built in four main sub-variants.[9][10]

Series 30 features[edit]

The DC-9-30 was offered with a selection of variants of JT8D including the -1, -7, -9, -11, -15. and -17. The most common on the Series 31 is the JT8D-7 (14,000 lbf (62 kN) thrust), although it was also available with the -9 and -17 engines. On the Series 32 the JT8D-9 (14,500 lbf (64 kN) thrust) was standard, with the -11 also offered. The Series 33 was offered with the JT8D-9 or -11 (15,000 lbf (67 kN) thrust) engines and the heavyweight -34 with the JT8D-9, -15 (15,000 lbf (67 kN) thrust) or -17 (16,000 lbf (71 kN) thrust) engines.[9][10]

Series 40[edit]

Northwest Airlines DC-9-40 flight deck

The DC-9-40 is a further lengthened version and entered service with Scandinavian Airlines System (SAS) in March 1968. With a 6 ft 6 in (2 m) longer fuselage, accommodation was up to 125 passengers. The -40 was fitted with Pratt & Whitney engines of between 14,500 and 16,000 lbf (64 and 71 kN). A total of 71 were produced.

Series 50[edit]

The Series 50 was the largest DC-9 to fly. It features an 8 ft 2 in (2.49 m) fuselage stretch and seats up to 139 passengers. It started revenue service in August 1975 with Eastern Airlines and included a number of detail improvements, a new cabin interior, and more powerful JT8D-15 or -17 engines in the 16,000 and 16,500 lbf (71 and 73 kN) class. McDonnell Douglas delivered 96, all as Model -51. Some visual cues to distinguish this version from other DC-9 variants include side strakes or fins below the side cockpit windows and thrust reversers rotated about 22 degrees on the original configuration. However various maintenance replacements have seen the thrust reversers in the same position as the -30 and -40.

Delta DC-9-51 Interior Cabin View N779NC

Military and government[edit]

Operators[edit]

Two British Midland DC-9s at Teesside Airport in 1994.
Perris Valley Skydiving DC-9-21, January 2008

A total of 77 DC-9 aircraft (all variants) were in commercial service as of January 2014, including USA Jet Airlines (10), Insel Air (7), Everts Air Cargo (3), Aeronaves TSM (6), Aserca Airlines (4), LASER Airlines (3), Fly SAX (2), African Express Airways (2), Fly540 (2), and other operators with fewer aircraft.[16]

Delta Air Lines since acquiring Northwest Airlines, has operated a fleet of DC-9 aircraft, most over 30 years old. With severe increases in fuel prices in the summer of 2008, Northwest Airlines began retiring its DC-9s, switching to Airbus A319s that are 27% more fuel efficient.[17][18] As the Northwest/Delta merger progressed, Delta returned several stored DC-9s to service. Delta Air Lines made its last DC-9 commercial flight from Minneapolis/St. Paul to Atlanta on January 6, 2014 with the flight number DL2014.[19][20]

Because of the usage of the aging JT8D engines, as of late 2000s (decade) DC-9s are considered gas guzzlers when compared to other more recent airliner designs. Studies aimed at improving DC-9 fuel efficiency, by means of retrofitted wingtip extensions of various types, have not succeeded in demonstrating significant benefits.

With the existing DC-9 fleet shrinking, modifications do not appear to be likely to occur, especially since the wing design makes retrofitting difficult.[7] DC-9s are therefore likely to be further replaced in service by newer airliners such as Boeing 737, Airbus A320, Embraer E-Jets, and the new, emerging Bombardier CSeries.[21] However, it is probable for several DC-9s to continue in service for years.

One ex-SAS DC-9-21 is operated as a skydiving jump platform at Perris Valley Airport in Perris, California. With the steps on the ventral stairs removed, it is the only airline transport class jet certified to date by the FAA for skydiving operations as of 2008.[22]

Deliveries[edit]

Deliveries[23]
TypeTotal198219811980197919781977197619751974197319721971197019691968196719661965
DC-9-101131029695
DC-9-10C24420
DC-9-201091
DC-9-30585810132411216212117424197161101
DC-9-30C3016413573
DC-9-30F642
DC-9-40715632427327210
DC-9-5096551015182815
C-9A218157
C-9B1721248
VC-9C33
Total97610161839222250424829324651122202153695

Accidents and incidents[edit]

As of March 2009, the DC-9 has been involved in 117 incidents, including 101 hull-loss accidents,[24] with 2,135 fatalities.[25]

Notable accidents[edit]

Itavia DC-9 (I-TIGI) was destroyed in an accident at Ustica. Shown in the "Museo della Memoria" opened in Bologna in 2007.

Aircraft on display[edit]

Specifications[edit]

DC-9-15DC-9-20DC-9-30DC-9-40DC-9-50
Flight crew2
Passengers
(1 class)[55]
90115125135
Length104 ft 4¾ in
(31.82 m)
119 ft 3½ in
(36.37 m)
125 ft 7¼ in
(38.28 m)
133 ft 7¼ in
(40.72 m)
Wingspan89 ft 5 in
(27.25 m)
93 ft 5 in
(28.47 m)
Height27 ft 6 in
(8.38 m)
28 ft 0 in
(8.53 m)
Wing Area934.3 sq ft
(86.77 m²)
1,000.7 sq ft
(92.97 m²)
Aspect ratio8.55:18.71:1
Empty weight49020 lb
(22,235 kg)
52,880 lb
(23,880 kg)
57,190 lb
(25,940 kg)
58,670 lb
(26,612 kg)
61,880 lb
(28,068 kg)
Max takeoff
weight[55]
90,700 lb
(41,100 kg)
98,000 lb
(44,500 kg)
108,000 lb
(49,090 kg)
114,000 lb
(51,700 kg)
121,000 lb
(54,900 kg)
Powerplants (2x)P&W JT8D-5 or -7P&W JT8D-11P&W JT8D-7, -9, -11, -15 or -17P&W JT8D-9, -11, -15 or -17P&W JT8D-15 or -17
Engine thrust12,250 to 14,000 lbf (54.5 to 62.3 kN)14,500 lbf (64.5 kN)14,000 to 16,000 lbf (62.3 to 71.2 kN)14,500 to 16,000 lbf (64.5 to 71.2 kN)15,500 to 16,000 lbf (69 to 71.2 kN)
Max cruise
(at 25,000 ft (7,620 m))
490 kn
(564 mph,
907 km/h)
494 kn
(569 mph,
915 km/h)
490 kn
(565 mph,
907 km/h)
485 kn
(558 mph,
898 km/h)
Max range1,590 nmi
(1,831 mi,
2,946 km)
1,605 nmi
(1,848 mi,
2,974 km)
1,670 nmi
(1,923 mi,
3,095 km)
1,555 nmi
(1,790 mi,
2,880 km)
1,795 nmi
(2,067 mi,
3,326 km)
Fuel capacity3,700 US gallons (14,000 l)3,679 US gallons (13,930 l)5,038 US gallons (19,070 l)
Allegheny Airlines DC-9-30 c. 1970
Comparison of McDonnell Douglas DC-9, Boeing 717, and different McDonnell Douglas MD-80 derivatives

Source: Jane's All The World's Aircraft 1976–77[56] except where specified.

See also[edit]

Related development
Aircraft of comparable role, configuration and era
Related lists

References[edit]

Citations[edit]

  1. ^ "DC-1 Commercial Transport". Boeing. Retrieved 27 March 2010. 
  2. ^ a b c d Endres, Gunter. McDonnell Douglas DC-9/MD-80 & MD-90. London: Ian Allan, 1991. ISBN 0-7110-1958-4.
  3. ^ a b c d Norris, Guy and Mark Wagner. "DC-9: Twinjet Workhorse". Douglas Jetliners. MBI Publishing, 1999. ISBN 0-7603-0676-1.
  4. ^ "The DC-9 and the Deep Stall". Flight International: 442. 25 March 1965. Retrieved 2011-10-07. 
  5. ^ a b c Air International June 1980, p. 293.
  6. ^ Air International June 1980, p. 292.
  7. ^ a b Assessment of Wingtip Modifications to Increase the Fuel Efficiency of Air Force Aircraft. The National Academies Press. 2007. p. 40. ISBN 0-309-10497-1. 
  8. ^ Burchell, Bill. "Setting Up Support For Future Regional Jets". Aviation Week, October 13, 2010.
  9. ^ a b c d e f g h i j k l Airclaims Jet Programs 1995
  10. ^ a b c d e f g h i j k l Jane's Civil and Military Aircraft Upgrades 1995
  11. ^ Shevell, Richard S. and Schaufele, Roger D., "Aerodynamic Design Features of the DC-9", AIAA paper 65-738, presented at the AIAA/RAeS/JSASS Aircraft Design and Technology Meeting, Los Angeles California, November 1965. Reprinted in the AIAA Journal of Aircraft, Vol.3 No.6, November/December 1966, pp.515-523.
  12. ^ The Boeing Company
  13. ^ http://www.flightglobal.com/pdfarchive/view/1969/1969%20-%200179.html
  14. ^ Schaufele, Roger D. and Ebeling, Ann W., "Aerodynamic Design of the DC-9 Wing and High-Lift System", SAE paper 670846, presented at the Aeronautic & Space Engineering and Manufacturing Meeting, Los Angeles California, October 1967.
  15. ^ Waddington, Terry, McDonnell Douglas DC-9; Great Airliners Series, Volume Four, World Transport Press, Inc., 1998, p.126. ISBN 978-0-9626730-9-2.
  16. ^ "Aircraft Quick Search". ch-aviation. Retrieved 09 Aug 2013. 
  17. ^ "To Save Fuel, Airlines Find No Speck Too Small". New York Times, June 11, 2008.
  18. ^ Soaring Fuel Prices Pinch Airlines Harder, Wall Street Journal, June 18, 2008, p. B1.
  19. ^ Trejos, Nancy (January 7, 2014). "Delta DC-9 aircraft makes final flight". USA Today. Retrieved January 16, 2014. 
  20. ^ http://www.cnn.com/2014/01/06/travel/delta-dc-9/index.html
  21. ^ "Bombardier Launches CSeries Jet". New York Times, July 13, 2008.
  22. ^ Perris Valley Skydiving DC-9 Video
  23. ^ Order and Deliveries - User Defined Reports. boeing
  24. ^ McDonnell Douglas DC-9-10/15 summary, DC-9-20 summary, DC-9-30 summary, DC-9-40 summary, DC-9-50 summary. Aviation-Safety.net.
  25. ^ McDonnell Douglas DC-9-10/15 Statistics, DC-9-20 Statistics, DC-9-30 Statistics, DC-9-40 Statistics, DC-9-50 Statistics. Aviation-Safety.net, 3 December 2007.
  26. ^ National Transportation Safety Board (1967-12-11). "Aircraft Accident Report. West Coast Airlines, Inc DC-9 N9101. Near Wemme, Oregon". Retrieved 2009-03-22. 
  27. ^ National Transportation Safety Board (1968-06-19). "Aircraft Accident Report. Trans World Airlines, Inc., Douglas DC-9, Tann Company Beechcraft Baron B-55 In-flight Collision near Urbana, Ohio, March 9, 1967". AirDisaster.Com. Retrieved 2008-11-23. 
  28. ^ Disasters: The Worst Ever
  29. ^ "Accident description". Aviation Safety Network. Retrieved 7 October 2009. 
  30. ^ NTSB Report (PDF)
  31. ^ McGlaun, Dan. "Allegheny 853 Crash Site Pictures". www.mcglaun.com. Retrieved 2008-01-27. 
  32. ^ D. Gero (2005-05-21). "ASN Aircraft accident McDonnell Douglas DC-9-32 HI-177 Santo Domingo". Aviation Safety Network. Flight Safety Foundation. Retrieved 2008-11-23. 
  33. ^ "Former Champ Teo Cruz Dies in Plane Crash". Modesto Bee (Modesto, California). Associated Press. 1970-02-16. p. A-6. Retrieved 2008-11-23. 
  34. ^ National Transportation Safety Board (1971-03-31). "Aircraft Accident Report: Overseas National Airways, Inc., operating as Antilliaanse Luchtvaart Maatschappij Flight 980, near St. Croix, Virgin Islands, May 2, 1970. DC-9 N935F.". AirDisaster.Com. Retrieved 2008-11-23. 
  35. ^ Mickolus, Edward F.; Susan L. Simmons (2011). The Terrorist List. Santa Barbara, CA: ABC-CLIO, LLC. p. 34. ISBN 978-0-313-37471-5. Retrieved July 19, 2012. 
  36. ^ National Transportation Safety Board Report Number NTSB-AAR-73-15 “Aircraft Accident Report North Central Airlines, Inc., McDonnell Douglas DC-9-31, N954N, and Delta Air Lines, Inc., Convair CV-880, N8807E, O’Hare International Airport, Chicago, Illinois, December 20, 1972,” adopted July 5, 1973
  37. ^ ASN Aircraft accident McDonnell Douglas DC-9-32 YU-AJO Praha-Ruzyne International Airport (PRG
  38. ^ National Transportation Safety Board (1978-01-26). "Aircraft Accident Report: Southern Airways, Inc. DC-9-31, N1335U. New Hope, Georgia. April 4, 1977.". AirDisaster.Com. Retrieved 2008-11-23. 
  39. ^ Vanderbilt, Tom (2010-03-12). "When Planes Land on Highways: The ins and outs of a surprisingly frequent phenomenon". Slate. 
  40. ^ Priest, Lisa; Rick Cash (2005-03-08). "Takeoffs and landings always pose risk of calamity, as history shows" (Fee required.). Globe & Mail (Toronto, Ontario, Canada). Retrieved 2008-11-23. "The last time an aircraft skidded off the runway in Toronto, seriously injuring passengers, was more than a quarter-century ago. On June 26, 1978, an Air Canada DC-9 skidded off a taxi strip at Toronto International Airport (what is today Pearson International Airport) during an aborted takeoff, then belly-flopped into a swampy ravine, killing two passengers and injuring more than a hundred others."  [dead link]
  41. ^ "ASN Aircraft Accident description of the 14 SEP 1979 accident of a McDonnell Douglas DC-9-32 I-ATJC at Sarroch". Aviation Safety Network. Flight Safety Foundation. February 21, 2006. Retrieved 2008-11-23. 
  42. ^ http://temi.repubblica.it/repubblicabologna-speciale-ustica/
  43. ^ http://www.reti-invisibili.net/ustica/articles/art_3901.html
  44. ^ http://www.airdisaster.com/cgi-bin/view_details.cgi?date=06271980&reg=I-TIGI&airline=Itavia
  45. ^ Accident description at the Aviation Safety Network
  46. ^ "ASN Aircraft accident Douglas DC-9-14 N3313L Detroit-Metropolitan Wayne County Airport, Michigan (DTW)". Aviation Safety Network. Flight Safety Foundation. 2008-11-23. Retrieved 2008-11-23. 
  47. ^ National Transportation Safety Board (1991-06-25). "Aircraft Accident Report: Northwest Airlines Inc. Flights 1482 & 299, Runway Incursion and Collision, Detroit Metropolitan/Wayne County Airport, Romulus, Michigan, December 3, 1990". AirDisaster.Com. Retrieved 2008-11-23. 
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  49. ^ "ASN Aircraft accident McDonnell Douglas DC-9-31F XA-TKN Uruapan." Aviation Safety Network. Retrieved on July 4, 2010.
  50. ^ "06 Oct 2000 accident entry." Aviation Safety Network. Retrieved on March 23, 2011.
  51. ^ "Plane crashes into African marketplace". CNN, April 15, 2008.
  52. ^ "Toll from Congo plane crash rises to 44". Associated Press, 2008-04-17
  53. ^ USA Jet Flight 199. aviation-safety.net
  54. ^ Washburn, Mark (January 23, 2014). "Delta’s last DC-9 retires at Charlotte museum". Charlotte Observer. 
  55. ^ a b c "DC-9: Airplane Characteristics for Airport Planning: Douglas Aircraft Company June 1984". Boeing. June 1984. Retrieved 20 June 2012.
  56. ^ Taylor 1976, pp. 330–331.

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