If Officer Friendly seems a shade less friendly than usual over the next few months, if that motorscooter woman scoots right on by when you try to flag her down for directions, if you wander into your local stationhouse to report a burglarly and the desk sergeant blithely refuses to look up from his desk - be tolerant. The police have other questions on their minds just now.

Questions like:

Can an arrest warrant for possession of marijuana be served on a Sunday?

Can the police impound a car that belongs to the wife of a cook at the Russian Embassy because of unpaid traffic tickets?

Does the officer riding in the back seat of a cruiser have to fasten his seat belt?

This is the season when officers, sergeants and lieutenants commence studying for the exams that will transform them into sergeants, lieutenants and captains. It's promotion time.

Of course, promotion is a year-round pursuit, like brotherhood, or getting re-elected to Congress. But the chase will grow more anxious this fall and next spring. And in March, 1978, if past experience holds, about 1,500 District of Columbia police officers will file into Roosevelt High School and MacFarland Junior High for exams to show the department just how much they know.

Getting promoted has been getting harder - a lot harder - since the District of Columbia police department began shedding manpower in 1971. And it is little consolation to the candidates themselves that the stiff competition has, by wide consensus, improved the general caliber of police officials.

Of 1,530 officers who took the 1971 promotional exam, 331 were actually promoted - in batches over the following year. Last year, 1,761 officers took the exam, and only 47 have thus far been promoted, even though the list now covers two years instead of one.

The really serious studying, when officers use weeks of annual leave in order to rendenvous with their D.C. codes, their police regulations and general orders, starts about a month before the exam itself. Between now and then, with varying degrees of dedication, upwardly mobile officers will be organize their papers, form study groups, attend in-service training classes, and even enroll in paid cram courses modeled on those to help law school graduates pass the bar.

"For a whole week before the exam, I didn't come out of the house," says third district Officer James Bialasik, who wound up No. 29 on the 1976 sergeants list and still doesn't know if he'll be promoted. Twenty-three sergeants have been named so far, and close observers - i.e. the candidates themselves - tend to feel that, at best, another dozen sergeants might follow before the current list expires next June.

"I keep hearing all these rumors," says Bialasik, vowing that if he doesn't make it he'll be studying just as hard for next year's test.

Sergeant's pay, he says, is a virtual prerequisite to raising a family. As a rank-and-file officer, "you can't afford to buy a house in this area and not have your wife working." Bialasik and his wife owns a $50,000 house in Rockville - "My brother has almost identical house in Buffalo, New York," he says, "and it cost maybe $20,000 less."

Another officer who has no idea if he'll be a sergeant or an also-ran is George Hartman, a 10-year-veteran who works as the seventh district youth division. "The thing that really gets to you is nobody says we're going to make so many sergeants . . . you just don't know," says Hartman. "They don't tell the officers anything. That doesn't help your morale."

Hartman was No. 63 on the last sergeant's list. "Former Chief Layton's son was just behind me," he says, "so I figured I got it made. But then they only promoted 40-some."

"I just hope they make up their minds pretty soon," Hartman says. "Opening those books up again will be really rough."

Beyond the exam, what determines an officer's place on the promotional list is the "suitability" rating handed out by his immediate supervisors. The top rating is a 120, and in the last two years, according to many officers, a 120 or something very close to it, has become almost essential.

To try to insure that the same standards will apply throughout the department, each police unit has to work things out so as to yield an average suitability raging of 108. One bizarre result is that supervisors occasionally scout around before rating time, asking officers questions like, "are you really studying?" in the hope of identifying subordinates who don't figure to score well on the exam. These people, it is assumed, won't suffer from being given rock-bottom suitabilities.And every low suitability rating makes another high suitability possible.

In 1974, Bialasik recalls, he had just snagged a detective assignment when one of his sergeants began conducting these pre-suitability rap-sessions. "I told him don't give me any more points than you have to," says Bialasik. "I wanted to be a detective." But three months later he decided, "I didn't care for it. If you like the glamour it's all right. I prefer the more rounded work of a patrol officer."

Most officers agree that the exams are fair - much fairer than they were about five years ago, anyway, when there were abundant complaints of trick questions and plain trivial questions. There is no such unanimity about the suitability ratings, which some suggest should be replaced with a simple 'eligible' or 'ineligible' rating. "If you're the person who's getting the 120, it's OK," is Hartman's assessment. "If you're not, you've got a problem."

The first time Larry Rosenberger became a sergeant was in 1971. A year later he left the department and his $13,500 salary to go into the trucking business with his father in Pennsylvania. "The grass always looks greener," says Rosenberger. "When you find out it isn't, a smart man turns around and goes back where he came from."

Rosenberger turned around, went back where he came from, and in February, 1973, rejoined the D.C. police department as an officer, at the starting salary of $10,500.

In '76 he was again eligible for sergeant, placed No. 1 on the list, and was promoted a second time.

Rosenberger studied for the exam with his friend David Baker, who is also assigned to the seventh district, but Baker placed only 31st, so he's still waiting.

The unusual number of promotions in '72 and '73. Baker feels has put a lot of pressure on officers to get promoted. "Citizens walk up to me on the street and say, 'Why aren't you a sergeant?" I've got people asking me daily. 'Have ya heard? Some people keep telling me I'm not going to be promoted, but I'm optimistic because if I sat here for a whole year and told myself I'm not going to make it I would go crazy."

"You don't have to be promoted to be successful" says Baker. "This department should make the scout car officer the supreme assignment. "But that's a philosophy, it turns out, that Baker means to apply to the department in general rather than to himself. He intends to be promoted.

Baker gives himself a share of the credit for Rosenberger's snagging the top spot on the list. During one of their study sessions, says Baker, he came across a general order on the routing of police resignations. "I said, "This is important. This is going to be on the test for sure.' And he said, 'There's no way . . . I'm not going to study with anybody who'd bother with a question like that.'

"So I Said, "OK, OK, just memorize these three points . . .' Naturally it was on the exam - and he remembered, and I didn't."