A committee of the MEtro board approved yesterday a $10 pass that would give transit riders $6 worth of subway trips and unlimited bus rides for two weeks, beginning July 1.

Like all Metro fare decisions, however, the pass is not as simple as it seems at first glance. It is one of only three different pass proposals Metro will probably bring to public hearing in the near future, and is only half of subway system.

If that package is adopted as presently envisioned, it will keep most of the fares stable for District of Columbia residents. It will increase the fare for suburbanites, and will make it necessary for every Metro rider to carry a pocket calculator to figure out how much the subway will cost.

There are the three two-week transit passes that have been approved by the Metro Revenue and Operations Committee:

The basic $10 transit pass. With the pass, the rider could take the subway for up to $6 worth of rides and board any Metrobus at any time for an unlimited number of rides for two weeks. However, the bus ride would have to be within one zone. The District of Columbia is, itself, one bus zone, so a person who uses the bus in the District could ride anywhere without paying additional fare. The pass would also be good for one-zone-only rides in Maryland and Virginia, but extra fares would be charged if a rider crosses a zone boundary. Making it more complicated is the fact that Metro is also considering limiting subway rides to $5 instead of $6.

The $16 transit pass, for Maryland residents. This pass would contain $7.50 worth of subway rides and unlimited bus rides. It would be particularly useful for maryland residents who take a bus into the District of Columbia, then transfer to the subway at such stations as Brookland, Rhode Island Avenue, Stadium-Armory, Potomac Avenue and Federal Center SW.

The $14 transit pass, for Virginia residents. It would contain $6 worth of subway rides and unlimited bus rides within Virginia. Fairfax County residents would continue to use only their Farecards and zone tickets. The Alexandria staff has expressed opposition to the pass and Alexandria also would be given the option of not participating.

A new fare structure for bus and subway lacks committee approval, although area politicians and technicians have been moving toward agreement. Meetings are scheduled today and again next Thursday to put together the final package, if possible.

Metro board chairman Joseph S. Wholey outlined for reporters yesterday the elements of the package presently under consideration:

Subway fares would be revised to make the short trip cheaper and the cents for the first mile and 5 cents for each succeeding mile. Rush hour is defined by Metro as 6 to 9:30 a.m. and 3 to 6:30 p.m. weekdays.

The first of two exceptions to the subway fare is that it would always cost at least 50 cents to cross the Potomac River by subway, even the 1.5 mile ride from Rosslyn to Foggy Bottom. That ride would only 35 cents under a strict application of the formula.

The second exception is that it would cost 50 cents to travel around downtown before and after rush hours. Downtown, for purposes of the special fare, would be defined as between Capitol South and National Airport on the blue line and between Union Station and Dupont Circle on the red line.

The lower base fare would make the short, inner-city trip cheaper or no more expensive by subway than it is now. The Potomac crossing charge would affect primarily Virginia riders. The downtown charge before and after rush hours would catch the Metro lunch bunch, who presumably can afford 50 cents one way.

District of Columbia officials have said that it is politically impossible for them to raise transit fares this year, an election year. Further, D.C. Transportation Director Douglas Schneider has expressed concern on many occasions that the residents of the region who can least afford and most need public transportation are getting hit most heavily with the Metro fare schedule. That schedule requires separate fares for bus and rail. The result, Schneider believes, has been that D.C. residents are not riding the subway but staying on the bus.

Schneider and District politicians as well are known to be concerned that Metro will become a subway system for whites and a bus system for blacks largely because of high subway fares.

Some bus fares would also be changed under the package outlined by Wholey:

The D.C. bus fares would remain the same as today.

The Virginia bus fare would be 50 cents at all times. Additionally, the 30 cents.

Maryland will reduce its bus zones from four to two. The present Zone 1 will remain, the three outlying zones will be combined into Zone 2. Maryland residents who start their homebound trip on the subway and transfer free to the bus today within the District of Columbia will have to pay zone bus charges if they do not buy the $16 transit pass.

After the pass and fare package is approved by the Metro board, perhaps as early as next Thursday, public hearings will be held.

Resolution of the pass-fare issue is essential before Metro's fiscal 1979 budget can be adopted. The board has deferred voting on the budget for three consecutive weeks, because the budget calls for a 7 percent across-theboard fare increase and Washington will not permit that to happen.

Metro financial planners estimate that the fare proposal Wholey outlined would increase the bus deficit by about $9 million systemwide, but decrease the rail deficit by about $4.2 million, for a net increase in deficit of about $4.8 million. Most of that increase -- about $3.6 million -- would be picked up by D.C. according to early estimates.

The transit pass concept is the place where most of the revenue loss occurs. It is presumed by financial planners that the pass provision which permits unlimited bus ridership will increase ridership.A result of that, however, is that each ride produces less revenue.

Those considerations were the ones that kept Fairfax County out of the transit pass concept for Virginia riders and that raised questions from the Alexandria staff. "I figure the transit pass would mean a $120,000 loss in revenue that Alexandria would have to make up," said Alexandria's Deputy City Manager Clifford Rusch. Metro's operating budget is projected at $191.1 million with a subsidy requirement of $94.5 million.