The Orange Line train that accidentally crossed to another track and derailed Jan. 13, killing three people, faced the threat of a collision with a second train due to faulty Metro operating rules, the National Transportation Safety Board said yesterday.

The train that derailed and a train approaching from the opposite direction were being operated manually, without computer safeguards against collision, a board report said. The board called on Metro to establish new guidelines to keep manually operated trains safely apart.

Metro officials yesterday questioned whether board investigators fully understand how Metrorail trains operate and questioned the need for new separation guidelines. General Manager Richard Page said he would seek clarification from the board. The two trains were stopped a safe distance apart, Page said, though he did say that under extreme circumstances a collision could have occurred.

The board yesterday issued 11 nonbinding recommendations designed to correct alleged safety deficiencies that it found in its investigation of the rush-hour derailment midway between the Smithsonian and Federal Triangle stations, Metrorail's first fatal accident.

The accident occurred after a switch mistakenly put a New Carrollton train on a cross-over track connecting the tunnel's two main tracks. The train stopped after its front wheels had reached the second main track. The train was backed up, but the front wheels remained on the second track, causing the car to be dragged diagonally between the parallel tracks and crushed against a concrete pillar.

Many aspects of the board's report repeated findings Metro made in an in-house investigation. Both found that subway personnel violated safety procedures repeatedly before and after the accident, allowing the "third rail" beneath the train to reactivate automatically as passengers were getting out, that training was slipshod and that emergency communications were poor.

The board called on Metro to improve training and implement periodic proficiency checks for its employes, to upgrade communications, and to clarify procedures for backing up trains, moving through switches and shutting off power. Yesterday, Page said that Metro had already taken those steps as a result of its own inquiry.

Metro has also suspended without pay the operator of the derailed train and a supervisor who was at the scene.

The board also recommended that Metro educate passengers on how to escape from a disabled train. Metro has intentionally put no information in its stations or trains on how to open doors, reasoning that in most cases safety will be better served if passengers remain inside and board a "rescue" train that pulls up behind the stricken train.

The board has opposed this approach for years. Yesterday, General Manager Page said Metro is studying the problem closely and has sent officials on safety fact-finding missions to two other subway systems since the accident.

Four of the board's recommendations concern manual operation of trains. Metro's trains normally run under the direction of a central computer that stops them automatically if there is a stopped or oncoming train on the track ahead. But for certain runs, such as passing a malfunctioning switch, operators switch to a manual mode that limits their speed to under 15 miles per hour.

Under this control, the report said, "There is no automatic train stop or other collision avoidance system which would prevent a manually operated train from colliding with a standing train in a limited visibility location."

The board said the derailed train and one that was cleared to pass the crossover switch from the opposite direction were in manual mode. Their operators could see only short distances due to curves in the tunnel, the board reported, and had not been advised of what track they should be on.

The board said that the result could have been "a head-on or side-rake collision, with the opposing trains each moving as fast as 15 mph."

Metro officials say such a collision would have been extremely improbable, because the trains were traveling very slowly and the oncoming train's operator would have had ample time to see the other and stop. The oncoming train stopped safely well back from the accident site, according to Metro officials.

Under the safety board's recommendations, any time that a train ran on this manual mode, Metro's central control room would set up an "absolute block," a restriction that only one train could be on a given segment of track at one time. For one train to advance, the train ahead would first have to move out of the segment.

The report also said that passengers in the train remained aboard it for up to 30 minutes, even though five Metro officials reached the accident scene almost immediately. None of the officials had the authority to begin evacuating the train, the board said. It called on Metro to speed the evacuation process.

Other details in the report:

* A hotline linking the control room with the Metro police and maintenance office was out of order the day of the accident as was a spare intercom headset.

* The control room chief had never ridden over the Orange Line since it opened for passenger service. Neither he nor the controller handling the trains "had a good working knowledge of rules and procedures and neither man had received any retraining in this area," the report said.