A few days ago, I reported on a Money magazine article about the Civil Aeronautics Board's definition of "on-time" performance for airliners.

The article had noted that the CAB concerns itself with flying time rather than arrival time.The magazine said tha if a flight is completed in no more than 15 minutes more flying time than it was scheduled for, it is accepted as "on-time," even if the plane was quite late in leaving one city and comparably late in arriving at the second.

Deborah Best Dunaway of the CAB's Bureau of Operating Rights informs me that there is "some understandable confusion" about her agency's definition of what is on time and what isn't.

First, she says, the public should know that the CAB publishes a monthly summary of "the airline's schedule arrival performance in the top 200 domestic markets. As indicated in this report, a performed flight is considered to be 'on-time' only if it arrives within 15 minutes of the arrival time shown in the carrier's official schedules. The Board publishes these reports to inform the public of each carrier's performance in specific city-pair markets."

Second, she adds, "the Board requires each carrier to perform a minimum of 75 per cent of its flights within 15 minutes of the elapsed time for such flights shown in official schedules filed with the Board. Contrary to your column, this requirement is not a schedule arrival standard; it is an operational standard designed to insure that carrier's schedules are based on realistic elapsed times between airports for the type of aircraft being operated, so as to avoid deception and insure the safety of the public."

Ms. Dunaway's letter concludes with these two paragraphs:

"It is important to distinguish between elapsed time performance and schedule arrival performance and schedule arrival performance since each serves a different purpose. Generally, the term 'on-time' applies to schedule arrival performance and it is used in the CAB reports as well as in a number of air carrier advertisements.

"Finally, the Civil Aeronautics Board is currently considering whether to establish on-time arrival standards in addition to the present reporting requirement."

A few words of comment seem in order.

1. I thought every government agency in Washington had me on its mailing list, but apparently this is not so. The CAB may publish a monthly summary of airline performance, but I have never seen one. How is this summary circulated, and how effectively does the CAB reach travelers with it? Have you ever seen one?

2. When several airlines claim to have the best "on-time" record, each establishes with me the same level of credibility as the various paoin relievers "most often recommended by doctors." Bah! Humbug!

3. The word "biweekly" has been so abused that standard dictionaries now say it is acceptable in the meaning of "twice a week" - and also "every two weeks." As a result, careful writers must now avoid using "biweekly." It no longer conveys information with precision.

It appears to me that the CAB has done violence to the meaning of the term "on-time", and that serious consideration should be given to switching to more precise language.

To me, a flight that is on time is one that arrives when it is scheduled to arrive, not at some later time.

Flights that arrive late should be grouped into categories such as "1 to 5 minutes late," "5 to 15 minutes late," "15 to 30 minutes late," and so on. The traveler who must make a close connection after landing does not consider a 15-minute delay inconsequential, and I find it inexcusable for CAB to have to offer a definition of "on-time" that is prefaced with the words, "Generally, the term 'on-time' applies to . . ."

Generally, my foot. Either on-time means on-time or somebody is playing fast and loose with the consumer again. It is unseemly to find the United States Government in the role usually played by Madison Avenue hucksters.

I take it that the last paragraph in Ms. Dunaway's letter means that at present the airlines need only report on how often they stay within 15 minutes of their promised schedule arrival times, but some thought is being given to "setting standards" for such performance. I must confess that I don't know what these words mean, either. Would there be punishment for those airlines that fail to measure up to the standards? What punishment? Would airline officials stand in a corner, turn into pumpkins, or what?