Last year Delta Air Lines promised to educate its employes about AIDS and the ways the deadly disease is transmitted. The company sought advice from recognized experts, and twice distributed information on acquired immune deficiency syndrome to airline personnel.

But a recent incident aboard a Delta plane suggests that the company's educational effort still has a few gaps. Here's what our reporter Jennifer Smith has learned:

Jim Leahy and John Schauer were flying Delta from Washington to Orlando, Fla., on the morning of Oct. 12. They noticed that several passengers were wearing gay-rights badges from the weekend march on Washington, but thought no more about it.

Then, after a snack was served, Leahy pointed out to his companion that the flight attendant had put on disposable plastic gloves to retrieve the plates and leftovers from the passengers. Schauer, a frequent airline passenger, said he had never seen that before. When they changed planes in Atlanta, they noticed that no gloves were worn by attendants on the other Delta plane. The two men are heterosexuals.

Delta spokesman Jim Lundy said he didn't know why a flight attendant would wear gloves while picking up refuse, but said he guessed it was up to each attendant's discretion.

Jim Brown, a spokesman for the Department of Health and Human Services, said wearing gloves for such a cleanup chore is not necessary to avoid AIDS contagion. "AIDS is not, I'll repeat, is not a casually transmitted disease," Brown said.

Delta's history of insensitivity to AIDS victims started at the top. In early 1985, the airline amended its contract of carriage to exclude passengers with AIDS. Ten days later, it rescinded the provision, after protests and a threat of legal action from gay rights organizations.

In August 1986, AIDS victim Mark Sigers flew Delta from San Francisco to Atlanta to visit his family. When Sigers boarded Delta to return to San Francisco, a flight attendant recognized him and claimed that he had required continual care by his companions on the first flight and had needed oxygen. He was then taken off the plane.

Sigers' companions, his brother and sister-in-law, said the flight attendant had lied. They said Sigers had been no trouble, sleeping most of the way, and had never used oxygen.

After being contacted by the California-based Mobilization Against AIDS, Delta apologized to the group and assured them it welcomed AIDS patients as passengers.

Three months later, though, Delta's insurance lawyers calculated the compensation for passengers killed in a crash and argued that since one victim was known to be homosexual, he probably had AIDS and soon would have died anyway. Therefore, they explained, compensation, based on expected lifetime earnings, should be less.

The Mobilization Against AIDS threatened to call a nationwide boycott of Delta, and the airline agreed to adopt a policy that it would not discriminate against passengers with AIDS. It also reiterated its promise to educate its employes about AIDS.