"Runaway Military Pensions" by Michael D. Mosettig (Op-Ed, March 1) is nothing more than a rehash of two intellectually dishonest stories sent out over the Associated Press wire.

First of all, military "retired pay" is not a "pension." Webster defines "pension" as "a gratuity granted as a favor." Military retired pay is a significant element of the military career package. It is unlike any other retirement system in the public or private sectors. It is not solely paid for services rendered but, in addition to its deferred compensation aspects, it is a retainer payment that keeps recipients under the Uniform Code of Military Justice and subject to recall to active duty.

Your writer says military retired pay is "the single fastest growing item in the Defense Department budget." He bases his statement on a comparison of 1964 figures and those of today. What he conveniently forgets to mention is that use of the 1964 date provides a distorted base; the 1964 retired population (410,853) largely reflects the abnormally small standing forces maintained prior to World War II, while the present number of military retirees (1,096,184 -- not the 21 million in your article), is a result of the large standing forces this nation required over the last three decades.

Retired pay costs are not out of control, as Mosettig alleges. They reflect the realities of an inflating economy. Average retired pay is $6,648 -- only slightly above the poverty level for a family of four. How can you tell the retiree who has given 20, 30, or more of the best years of his life that his poverty level retired pay is out of line? Every dime was earned through honest service in the defense of the United States and the free world.

Your writer suggests that "within 25 years, the annual cost of military pensions could reach $30 billion or more in constant dollars." Using the same inflation factor (5 per cent annually), your $5,000 automobile will cost about $17,000 and an Army private would be making over $25,000. Ludicrous, isn't it, that the writer who should put those figures into perspective for the reader didn't even try?

We certainly do recognize that compensation needs to be reviewed from time to time to insure that it continues to be based on conditions today and is designed to attract quality men and women to make the sacrifices necessary in our defense in the future. Logic dictates a fair remuneration for this important segment of our society.

By selective omission of pertinent facts, the writer managed to imply that most military personnel voluntarily retire after 20 years service, regardless of age. To be objective, he should have mentioned that only one of every 10 individuals who enter the military service ever reach retirement eligibility. Not only is the military career more hazardous than the civilian occupation, but it also demands a unique degree of dedication to duty even above self and family. Few are able and willing to stay in service, despite the possibility of early retirement. Consider, too, that many who have served honorably are forced out early --some prior to retirement eligibility -- victims of the "up or out" policy that is designed to keep only the best leaders.Others, having served 20 or more years, are retired involuntarily to keep the ranks filled with young, vigorous personnel.

Serious factual inaccuracies were repeated in stating that the military retiree "gets from 50 to 75 per cent of active duty pay as pension." Military retired pay is computed on base pay, not on active duty pay. The military equivalent of active duty pay for purposes of compensation comparison is Regular Military Compensation (RMC). RMC is defined in law as the sum of basic pay plus quarters allowance plus subsistence allowance plus federal tax differential. For retirement at 20 years service, military retired pay is between 33 and 40 per cent (depending on grade) of RMC. The maximum possible retired pay for 30 or more years of service is between 49 and 51 per cent of RMC. Therefore, the range of retired pay as a percentage of "salary" is 33 to 61 per cent -- not your 50 to 75 per cent.

Military retirees fulfilled the provisions of their contract stipulated by the American people through the Congress. Military retirees have nothing to apologize for.

At the very time President Carter has granted amnesty to those who refused to serve their country in time of war, it is a gross paradox that some short-sighted persons would suggest the American people renege on the benefits promised those who served their nation faithfully.