27th Congress of International Council of the Aeronautical Sciences, 19 - 24 September 2010, Nice, France
Paper ICAS 2010-1.4.1

WHY COMMERCIAL JET PLANES CRUISE AT 30,000FT? CONCEPTUAL OPTIMAL CRUISE ALTITUDE

J.-L. Boiffier, L. Bovet*
Isae-SupAéro and Onéra, France; *Airbus, France

Keywords: aircraft design, conceptual design, cruise altitude, optimum

The jet commercial airplanes cruising altitude near 30000ft, is demonstrated as a conceptual optimal altitude, chosen by the designer and not by the pilot. This optimum results from the gain of a good L/D with the altitude which is paid with an increasing empty weight.

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