When Birds Become Missiles.(migrating birds and planes cause accidents in Israel)

Yossi Leshem's mission in life is to keep feathered fliers and planes from colliding

September 7, 1997. An Israel Air Force F-16 fighter worth more than $20 million streaks low during training exercises above the Negev Desert. Suddenly a honey buzzard smashes through the windscreen. Because of the plane's 900-kilometer-per-hour (560-mph) speed, the bird hits with an impact of about 25 tons. Captain E and First Lieutenant G (their names are classified) bail out. The captain suffers only a broken nose, but the lieutenant's leg is later amputated.

August 10, 1995. While on a routine training mission, an F-15 Falcon going about 1,000 kilometers per hour (620 mph) collides with three migrating white storks. Two of them strike the jet's body and the third is sucked into the engine. Each three-kilo (6.6-lb.) bird hits with a force of about 40 tons. Within seconds, the $50 million jet erupts in flames, inverts and crashes into the Negev. Captain Ronen Lev, the pilot, and Captain Yaron Vivante, the navigator, are killed.

yossi leshem's eyes dance as his glider sails silently through the middle of a giant flock of migrating white storks. "The stork is a symbol of spring, of luck," the Israeli ornithologist says as he checks the glider's instruments. "But not if it hits a plane."

Keeping planes from hitting birds is what Les- hem's life is all about. And in Israel that is not an easy task. Every spring and fall more than half a billion birds from three continents funnel across this tiny nation about the size of New Jersey. During migration seasons, Israel has the highest concentration of birds per square kilometer of any country in the world. It also has the world's greatest concentration of fighter aircraft.

For Israeli Air Force pilots, who can cross the country …