Let's take the case of the Airbus A320 family of aircraft. Airbus manufactures A318, A319, A320 and A321 planes, which all belong to the same family.

What is the need to manufacture multiple aircraft from the same family having different ranges and capacity, when one could just invest in making just two or three different planes from three different families providing a wide range of range (distance) and capacity?

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    $\begingroup$ Note, that distinction between A318-A321 is comparable to distinction between B737-100-B737-900. A320 is the only type where the main number is varied, but almost every type has multiple variants. $\endgroup$
    – Jan Hudec
    Jun 2, 2015 at 9:39
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    $\begingroup$ It was just an example $\endgroup$ Jun 2, 2015 at 9:52
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    $\begingroup$ I understand. I am just noting that that particular example is special in the naming, though not in principle. $\endgroup$
    – Jan Hudec
    Jun 2, 2015 at 10:02
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    $\begingroup$ Saying that a company could "just" make several completely different products instead of making variants of a single product is exactly backwards. The use of "just" implies that it would be the easier alternative but it seems completely obvious that it isn't. I'm not sure why you think it would be easier to design multiple independent products than design variants of a single product. $\endgroup$ Jun 2, 2015 at 10:53
  • $\begingroup$ See this answer or this. Make sure to read the comments, too. $\endgroup$ Jun 2, 2015 at 11:51

1 Answer 1


There are several advantages, here are a few:

  • Design costs are lower for a family of aircraft; major parts of the aircraft are the same in the family.
  • A family of aircraft share the same type certificate. This means it is cheaper for the manufacturer to certify a family of aircraft.
  • Within a family of aircraft, pilots can operate all aircraft with no or very little additional training required. This saves the airline a lot of money.
  • Maintenance on a family of aircraft is cheaper since the majority of parts are common to all family members. This means having less spare parts in stock and less training for maintenance personnel.
  • For an airline there is often a benefit in having some capacity diversity in a fleet. A new route often starts at low capacity. When the volume of passengers rises replacing the flight by a larger aircraft from the same family is not disruptive to crew schedules.

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