Soviet fighter jets were scrambled last week as a Japan Air Lines 747 jetliner, flying off course with 132 persons aboard, approached Sakhalin Island near the spot where the Soviets shot down a Korean Air Lines jumbo jet in 1983.
The Japanese jet's crew discovered they had made a navigational error and righted their course before the airliner improperly entered a sensitive area of Soviet airspace, Japanese officials said today, adding that the plane never came into contact with the Soviet fighters.
"The incident happened due to insufficient checking by the pilot. We are going to make strong efforts that it does not happen again," Hideo Hirasawa, the airline's managing director, said today. He promised "severe" disciplining of the pilot.
The incident has attracted major interest here because of similarities to the case of Korean Air Lines Flight 007, which was shot down Sept. 1, 1983, by a fighter off Sakhalin after flying through Soviet airspace for an extended period. All 269 aboard were killed.
Moscow contends that the South Korean plane was on a spying mission. The United States and South Korea have denied that and said it was probably off course due to navigational error. The jet's flight recorders have never been recovered and many questions remain unanswered.
The latest incident, on Oct. 31, came several weeks after the Soviet Union, United States and Japan signed an air-safety agreement to help prevent incidents along the Siberian coastline, which parallels routes heavily traveled by commercial and military aircraft.
Officials from the three countries are still discussing technical details and the accord has not taken effect.
Nonetheless, Japanese officials said the Soviets' response this time suggested a change in attitude. "The spirit of the agreement was behind the resolution of this incident," a Japanese Foreign Ministry official said today. Moscow has made no public comment.
The Japanese plane, a long-range model Boeing 747 operating as Flight 441, took off from Tokyo's international airport at Narita at 12:14 p.m. with 110 passengers and a crew of 22. Bound for Paris with a stop at Moscow, it was to enter Siberian airspace near the coastal town of Nakhtakhe.
Flying on automatic pilot, the jet neared heavy clouds over the Sea of Japan shortly before 1 p.m. The pilot decided to break course briefly to skirt them and switched off the automatic pilot's inertial navigation system in order to do so.
After the clouds had been passed, he forgot to turn the system back on, according to official accounts.
The plane, now following a magnetic heading rather than the system's more sophisticated guidance, began drifting toward the east, due to strong winds. Making a routine check of their position near a navigation beacon, the crew made a second mistake by failing to realize they were 20 miles off course. The jet was now heading toward Sakhalin, where it had no permission to go.
Several Japanese military radar sites recognized it was off course, a spokesman for the Japan Defense Agency said today. Military authorities then alerted Japanese civilian controllers and tried to raise the crew on a special emergency radio frequency. There was no reply.
A Japan Air Lines spokesman said the volume control on the emergency radio, which is rarely used, had been turned down so low that the crew could not hear the call.
Japanese military radar also picked up two or more unidentified aircraft circling over Sakhalin at the time, apparently interceptors waiting to see if the plane would enter Soviet airspace there. There are a number of highly sensitive military installations on the island.
At 1:47 p.m., with the plane about 60 miles off course, the crew finally discovered the error, the airline said. With the flight engineer keeping an eye out the window for interceptors, the crew radioed Soviet controllers who direct the international airspace the plane was in.
With clearance from the Soviets, the jet made a sharp left turn and went back toward normal course. It entered Soviet airspace at the correct point and flew on, without further trouble, to land in Moscow.
The plane never crossed into Soviet airspace at Sakhalin and the interceptor jets do not appear to have come closer than 30 miles or so to it. Misuse of an inertial navigation system system also has been cited as a possible explanation for how the Korean jet got into Soviet airspace.
Japanese military controllers' attempts to warn the JAL jet are also of interest for the KAL investigation, due to contentions by victims' families that U.S. authorities knew of the KAL jet's course and failed to issue a warning. The United States has denied these allegations.
The latest JAL incident follows the Aug. 12 JAL 747 crash into a mountainside near Tokyo, apparently due to faulty body repairs, killing 520 persons.
JAL President Yasumoto Takagi is scheduled to resign shortly to take formal responsibility for the crash. In the meantime, the government has issued orders for tightened maintenance and other safety procedures. The government owns 35 percent of the airline.
In response to last week's incident, airline officials said, JAL pilots will be required to announce to each other any changes involving the automatic pilot