Complex sentence: A new double deck widebody has proved to be extremely expensive and complex to develop, even for the remaining aerospace giants Boeing and Airbus, although the massive Airbus A380, a similar concept to the MD-12, has been successfully brought to fruition.
Split into simpler sentences: A new double deck widebody has proved to be extremely expensive and complex to develop, even for the remaining aerospace giants Boeing and Airbus. The massive Airbus A380, a similar concept to the MD-12, has been successfully brought to fruition.