Spurred by a sharp drop in sales of civil aircraft, this year's overall aerospace industry sales will fall slightly below 1981's for the first year-to-year decline since 1972, the Aerospace Industries Association said yesterday.

The industry group said sales will total $63.3 billion in 1982, down $190 million from 1981.

Preliminary figures show that 1982 sales of civil aircraft will plunge to $11.2 billion from $17.4 billion last year.

Karl G. Harr Jr., president of the Aerospace Industries Association, attributed the 36 percent decline--to the lowest level since 1978--to the recession and financial hard times for the world's airlines.

The decline in sales of civil aircraft was partially offset by a substantial increase in sales of military aircraft, to $22.8 billion from $19.2 billion in 1981, and by increases in the sales of missiles and space-related equipment, also largely military. The increase in the military sector reflects the Reagan administration's commitment to increased defense spending, Harr said in his annual year-end review and forecast at an Aviation Space Writers Association luncheon.

The sharp decrease in sales of civil aircraft--particularly commercial transports--will have a significant effect on the industry's export sales, despite record level of military exports, he said. Total exports in 1982 are estimated at $15.2 billion, down $2.4 billion from 1981's $17.6 billion. The big dip was in civil sales, which were down $3.3 billion to $10 billion in 1982. In contrast, military exports will be up $1 billion to a record $5.3 billion.

Because of the decline in exports, the aerospace industry's balance of trade--the traditional bright spot in the nation's bleak balance picture--is estimated at $10.7 billion this year, down $2.4 billion. In each of the last five years, the industry had record-setting levels of exports and trade balance, Harr said. Harr said the AIA expects sales to rebound in 1983 to a total $69.3 billion.