Up to 1980, the important European airports and European airlines increased the number of their flights and passengers. As a result, it has been necessary to develop and launch airplanes with a high passenger capacity (e.g., Boeing 747, Jumbo, with 270 seats; Douglas DC 10 with 265 seats; and the Airbus A 300 with 249 seats). Simultaneously, the airports had to be enlarged or even rebuilt. After this substantial investment, the number of passengers began to decrease. In 1981, the French airline “Air France” expected a deficit of about 65 million DM (29.5 million US dollars), excluding the deficit by Concord. For the first time in 18 years, the Scandinavian airline “SAS” in 1980 had a deficit. The German airline “Lufthansa” expects no profits in 1981. This situation has been caused by rising oil prices, decreasing numbers of passengers, and a general recession. Many airlines have been reducing prices to attract more passengers. In spite of the high investments in new airplanes and modernizing airports, there has been little improvement in the necessary air- and ground-control-systems.In April 1981, the International Associates of Pilots (IFALPA) graded the security of air- and ground-control-systems of German airports as follows: deficient — Frankfurt and Bremen; seriously deficient — Hamburg, Stuttgart and Saarbrücken. According to the security scale of the IFALPA, the most important airports in the Mediterranean area were surveyed and estimated in 1977/78 as follows: deficient — Los Rodeos (Canary Islands), Las Palmas (Canary Islands), Lisbon, Faro, Malaga, Alicante, Madrid, Gerona, Ibiza, Palma de Mallorca, Venice and Roma; and critically deficient — Alghero, Rimini, Naples.
Energy impact of the air infiltration in residential buildings in the Mediterranean area of Spain and the Canary islands
