Transport category is a category of airworthiness applicable to large civil airplanes and large civil helicopters. Any aircraft's airworthiness category is shown on its airworthiness certificate. The name "transport category" is used in the USA, Canada, Europe and many other countries.

Transport category airplanes are either :

• Jets with 10 or more seats or a maximum takeoff weights (MTOW) greater than 12,500lb (5670 kg); or
• Propeller-driven airplanes with greater than 19 seats or a MTOW greater than 19,000lb (8618 kg).

Transport category helicopters typically have maximum takeoff weights greater than 7,000 lb (3 175 kg) although there is no lower weight limit.

Easily recognisable examples of transport category airplanes are Boeing

Boeing

The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...

 and Airbus

Airbus

Airbus SAS is an aircraft manufacturing subsidiary of EADS, a European aerospace company. Based in Blagnac, France, surburb of Toulouse, and with significant activity across Europe, the company produces around half of the world's jet airliners....

 aircraft, Learjet 30 series, de Havilland Canada Dash 8, Embraer EMB 120 Brasilia

Embraer EMB 120 Brasilia

-Accidents:*Brazilian Air Force on July 8, 1988 an Embraer EMB 120RT Brasília registration FAB-2001 crashed during and engine-out landing at São José dos Campos. Five of the 9 occupants died....

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Easily recognisable examples of transport category helicopters are Bell 412

Bell 412

The Bell 412 is a utility helicopter manufactured by Bell Helicopter. It is a development of the Bell 212 model, the major difference being the composite four-blade main rotor.-Design and development:...

, Eurocopter Super Puma

Eurocopter Super Puma

The Eurocopter AS332 Super Puma is a four-bladed, twin-engine, medium-size utility helicopter marketed for both civil and military use. Originally designed and built by Aérospatiale, it is an enlarged and re-engined version of the original Aérospatiale Puma...

, MBB/Kawasaki BK 117, AgustaWestland AW139

AgustaWestland AW139

The AgustaWestland AW139 is a 15-seat medium sized twin-engined helicopter manufactured by AgustaWestland. Originally designed and developed jointly by Agusta and Bell Helicopters and marketed as the Agusta-Bell AB139, it was redesignated the AW139 when Bell withdrew from the project...

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The Convention on International Civil Aviation

Convention on International Civil Aviation

The Convention on International Civil Aviation, also known as the Chicago Convention, established the International Civil Aviation Organization , a specialized agency of the United Nations charged with coordinating and regulating international air travel...

, and particularly its Annex 8 Airworthiness of Aircraft, specify standards that must be met by each civil airplane and civil helicopter that is used in international aviation. These standards apply if the airplane has a maximum takeoff weight greater than 5 700 kg, or the helicopter has a maximum takeoff weight greater than 3 175 kg.

In the US the standards in Annex 8 are incorporated in:

• for airplanes: Part 25 of the Federal Aviation Regulations
  Federal Aviation Regulations
  The Federal Aviation Regulations, or FARs, are rules prescribed by the Federal Aviation Administration governing all aviation activities in the United States. The FARs are part of Title 14 of the Code of Federal Regulations...
  
   titled Airworthiness Standards: Transport Category Airplanes
• for helicopters: Part 29 of the Federal Aviation Regulations
  Federal Aviation Regulations
  The Federal Aviation Regulations, or FARs, are rules prescribed by the Federal Aviation Administration governing all aviation activities in the United States. The FARs are part of Title 14 of the Code of Federal Regulations...
  
   titled Airworthiness Standards: Transport Category Rotorcraft

Parts 25 and 29 are applied to transport category airplanes and helicopters in the US and many other countries where large airplanes and helicopters are designed and manufactured. In Europe the European Aviation Safety Agency

European Aviation Safety Agency

The European Aviation Safety Agency is an agency of the European Union with offices in Cologne, Germany, which has been given regulatory and executive tasks in the field of civilian aviation safety. It was created on 15 July 2002, and it reached full functionality in 2008, taking over functions...

 has similar certification standards, also titled Parts 25 and 29, for application to large airplanes and helicopters.

A principle behind transport category design standards is that any element in an airplane or helicopter can fail, but the risk of such a failure causing an accident should be extremely low. Consequently transport category airplanes and helicopters have duplicated elements wherever failure of one element is likely to cause an accident. For example, transport category airplanes must have at least two engines and be flown by at least two pilots. The loads on the wings and tailplanes are usually carried by multiple load paths. If one element of the primary structure fails due to metal fatigue

Fatigue (material)

'In materials science, fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. The nominal maximum stress values are less than the ultimate tensile stress limit, and may be below the yield stress limit of the material.Fatigue occurs...

 or corrosion

Corrosion

Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...

 the remaining sound elements of the structure must carry the loads until the failed structural element is discovered in routine maintenance. This fail-safe principle is not necessary in airplanes and helicopters that are not certificated in the transport category.

If an element in a transport category airplane or helicopter is not highly critical, or if its failure is relatively benign, it is possible for that element not to be duplicated. For example, most transport category airplanes do not have duplicated nosewheel assemblies; and some do not have duplicated wheels on each main undercarriage.

A transport category helicopter is permitted to have only one main rotor head, and may have only one engine. If a transport category helicopter has only one engine it is only eligible to be a Class B (or Performance Group 2) helicopter. An example of a transport category helicopter with only one engine is the Bell 204/205

Bell 204/205

The Bell 204 and 205 are the civil versions of the ubiquitous UH-1 Iroquois single-engine military helicopters. They are type-certificated in the transport category and are used in a wide variety of applications, including crop dusting, cargo lifting, and one of its most common uses, aerial...

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Other categories of airworthiness used in the US, Canada, Australia and numerous other countries are:

• normal category
• utility category
• acrobatic category
• commuter category
• restricted category
• primary category
• manned free balloon