The safety board has been active in recent weeks in other transportation areas. For example:

* People should be prohibited from riding in the open cargo areas of pickup trucks and similar vehicles, a special study says, because they risk their lives needlessly when they do.

An average of 242 people were killed each year from 1975 through 1979 while riding in open cargo areas, the board said, including seven teen-agers who died that way in a truck accident near Crofton in 1979 that claimed 10 lives. The board urged the National Committee on Uniform Traffic Laws and Ordinances to establish model ordinances that could be adopted by states, but noted that the committee has "has not yet acted . . . because of a lack of funds."

* The Federal Aviation Administration should require that crew members on passenger planes be trained and equipped to communicate with passengers once the main electrical supply and public address system is gone (which happens if the engines are shut down in an emergency).

The recommendations followed the evacuation of 238 people from a United Airlines DC8 that had a fire in the landing gear well. Only two people were hurt seriously, but the evacuation was slow and confusing because passengers had trouble hearing instructions. The NTSB has been nagging about this for 10 years, it said, "and still the FAA has not acted . . . "

* When railroad tank cars that carry hazardous materials are emptied, the shipping papers that accompany them should identify the last thing they carried.

That recommendation to a Transportation Department agency followed the derailment at Surf, Calif., of a Southern Pacific freight train in which 13 people were overcome by toxic hydrogen fluoride fumes from an "empty" tank car. It took rescuers several hours to learn what chemical they were dealing with. The definition of "empty" also needs a little work, NTSB said.