Experience with a multi-year fleet planning model

The fleet planning problem requires determination of the changing airline fleet mix based on existing traffic levels and projected growth, on the existing fleet, various aircraft types available in the future, and other operational and financial considerations. Several applicable mathematical formulations have been reported. One of these has been programmed for the computer and used by the authors for several years. This paper discusses the application of that model to real airline planning situations. Such practical experience has effected changes in the program and the manner it is used in fleet planning studies.     

Causes of Uruguayan migration to Argentina

2 main hypotheses have been suggested to explain Uruguayan migration to Argentina: 1) political emigration because of the military regime imposed in June 1973 and 2) economic emigration because of the economic improvement in destination countries and the worsening conditions at home. A further formulation of the 2nd hypothesis incorporates sociodemographic factors in its theory. This paper elaborates a theoretical framework using human capital theories to formulate a model of the effects of the economic variables of wages and unemployment, and adds political and sociological variables to the model. The authors then quantify the relative effects of the political, human capital, and informational variables. Results of multivariate analysis show that for 1966-1981, 53.1% moved for economic reasons, 25.7% moved for political reasons, and 21.2% moved for social reasons. In the long run, the most important cause of migration to Argentina is related to the relative situation of regional labor markets and people's willingness to incur the costs of migration if there is a reasonable probability of economic improvement in the other country. Only from 1973-1975 are political and institution reasons of primary importance. In 1976, sociological reasons predominated.