Boboc Air Base, ROMANIA - For some of the senior Israel Defense Forces officers participating in the search operation to find the crew members killed when the CH-53 Sikorsky helicopter crashed in the Carpathian Mountains, it felt like closing a circle. Thirteen years ago they were searching for the bodies of the pilots and soldiers killed when another two CH-53 helicopters, known as Yasurs, collided over Moshav Shaar Yishuv on their way to Lebanon.

Apart from the fact that both involved the same helicopter model, there are no similarities between the two accidents. The scope is different - 73 crew members and fighters perished at Shaar Yishuv, while six crew members and a Romanian liaison officer were killed Monday in Romania - as are the ramifications for the air force and the IDF.

In the wake of the Shaar Yishuv disaster, senior officers were deposed and the air force carried out a comprehensive helicopter safety reform. This included creating an entirely new position: head of the helicopter air group, a brigadier general. The IDF ground forces had accused the air force commanders of scorning the helicopter fleet, which works daily with ground forces. According to the accusation, the fleet was belittled, compared to the glorified combat squadron, which produced the vast majority of the air force's top brass - indeed, all the commanders have been fighter pilots.

However, the disaster led to much greater investment in helicopters, a significant improvement in flight safety and a growing recognition that cooperating with the ground forces is one of its main functions. It is already possible to say with certainty that despite the profound sadness over the loss of four pilots and two flight engineers, all highly regarded and experienced, and despite the important conclusions that will be drawn concerning flights during bad weather, the air force emerged strengthened.

The disaster has demonstrated the difficulty and complexity of the force's missions - in training and, even more so, in operational activity. The heads of the air force said this week that the crash will not affect the force's plans to hold more maneuvers in foreign countries, far from Israel's borders. On the contrary, said one senior officer this week: The accident has only underscored the need for maneuvers of this sort, over unfamiliar terrain and in conditions quite different from the familiar, convenient skies of Israel.

Though hundreds of thousands of Israelis know Romania as a nearby, convenient tourism destination - a two-and-a-half hour flight from Ben-Gurion International Airport - the eight Yasurs participating in the exercise that began July 18 spent 10 exhausting hours getting from their home base in Tel Nof to the Romanian air base at Boboc, including an in-air refueling by a Hercules plane somewhere over southern Greece.

Moreover, the two-week stay also required what the air force calls "deployment": precise logistical preparations that took many months. In addition to the flight crews, technical crews and administrative, teleprocessing and air-control personnel also went to Romania.

The commander of the drill was Lt. Col. Y., commander of the Night Predators squadron, which suffered the casualties. Because of the great importance of the exercise, crews from the other Yasur squadron, the Night Transporters, also participated. Every few days additional crew members arrived on commercial flights. Many are veteran reservists or pilots filling other roles in the air force whose "emergency" posting is in the CH-53 squadron.

The moment the investment is made in an exercise like this one, everything is done so that all the pilots will benefit, even those who have already done and seen everything. Thus, the casualties ranged in age from 24 to 48.

The "Blue Skies" maneuvers in Romania offered the CH-53 pilots many conditions not present in little Israel, including a long flight over an area they'd seen only in maps, topography that changes frequently from broad plains to mountain ridges up to 2,500 meters high, extreme weather including heavy fog and sudden summer thunderstorms.

On the approach road to the Romanian air base at Boboc, where the exercise was conducted, you could see another reason for maneuvers in Romania and other countries in Central and Eastern Europe: batteries of Soviet-produced anti-aircraft missiles and radar. The air defense systems of many of those countries are still based on the missiles and doctrine of the Warsaw Pact days, as is true for most of the countries where the air force might see action. Two months ago, Israeli air force combat planes participated in a complex exercise in Greek skies.

Notwithstanding the high regard in which the Israel Air Force is held in foreign publications, it is well aware that its pilots have not been tested in all-out war against a state with an air force and air-defense system since the 1982 attack on the Syrian missile deployment in Lebanon.

Following Operation Cast Lead, IAF commander Ido Nechushtan said his major conclusion was that despite the operational successes, he did not know how his pilots would handle a new and different situation: Some hadn't yet been born when the last air battle occured. The maneuvers in foreign countries have been aimed at addressing this lack of combat experience.

While Israel appears to be isolated in the diplomatic arena, at the military level many armies abroad are lining up to host Israel for joint exercises, put their facilities at the IDF's disposal and benefit from the pilots' experience.

IAF pilots rejected any doubts over their force's ability to carry out missions in faraway countries that might have been raised by the crash. The fact that the force is training in difficult and challenging configurations, and involved in large "deployment" operations, is proof of its capability.