The bombing run consisted essentially of seven elements, or timings. After pop-up, the second element was the pull-down altitude, the preset altitude at which the pilot pushed the nose down and began the dive toward the target. It was imperative that this elevation be as low as possible without endangering the accuracy of the dive because a shorter dive distance lessened the pilot’s exposure to AAA and SAM fire. The third point was the apex altitude. This was the altitude the plane climbed to during the fraction of a second it took the electrical impulse from the control stick to reach the plane’s mechanics controlling the wing flaps. At six hundred miles an hour, the F-16 could cover a considerable distance in a split second. The apex altitude was the exact point at which the dive would start and, like the pull-down point, it had to be as low as possible. The fourth element of the bombing run, called tracking on final, was the actual dive itself, measured from the apex altitude to the release point, the fifth element of the bomb run and the altitude at which the ordnance was dropped. The pilot kept his bombsight lined up on the target until the pipper, or “death dot,” covered the target completely. At that moment he squeezed the red button on the control stick and the bombs were released, or “pickled,” off the wings. The time of tracking on final, from high to low as pilots referred to it, had to be between three and five seconds.
As soon as the pilot released ordnance, he initiated the sixth element, recovery, or escape, firing afterburners and trailing thruster flames, climbing to high altitude. As the pilot began his escape and climb, there was another split second between the time he pulled back on the fly-by-wire control and the actual response of the aircraft mechanics. During this fraction of a second the plane would “settle,” or sink, to a lower elevation. Predetermining this lowest point of the dive, called the recovery altitude, was absolutely essential, since the pilot had to avoid the frag pattern, the bloom of shrapnel and debris following detonation, which, in the case of the MK-84, rose 2,400 feet in nine seconds. The pilot, if not careful, could easily blow up himself and any fellow pilots following too closely. The final element of the bombing run was the escape maneuver, during which the pilot could hit a body-crushing eight Gs while negotiating radical 90-degree turns and climbing to 30,000 feet to defeat SAMs.
To compute the precise distance from the target to initiate pop-up, what angle to start tracking on final, the exact altitude of apex, and all the rest, Avi Sella’s team thumbed through engineering books thick as IRS tax rolls, poring over computer graphs and charts and physics tables to check and recheck their figures. The concept was basically computing backward: first determine the altitude of the frag envelope, then add the recovery time, the pull back, then tracking on final, and so on. Once these figures were computed and added together, the sum determined the exact altitude to the meter at which the squadron commander would begin his dive. Each pilot would then, in turn, follow precisely.
Operations initially determined that pull down should start at around 8,000 feet. The U.S. Air Force routinely added a cushion of 500 feet when computing their recovery altitude. But the Israelis, fearful about the heavy AAA defenses, were determined to squeeze every fraction of a second out of the tracking time. Sella’s team figured that because the bombs would pierce the reactor cupola and fall through before exploding inside, the dome itself would function as a shield, cutting the frag pattern in half. The decision was made to press the attack to the absolute minimum distance, with no safety net. To add a degree of security and ensure that follow-on pilots would continue to have an unobstructed view of the target, the bombs of lead pilots Raz and Yadlin would be rigged with delayed fuses.
Behind every maneuver was the element of speed, sometimes suicidal speed. After weeks of test dives and modeling and more test dives, Raz and his team were able to cut the apex altitude to only 5,000 feet, shaving off valuable seconds in both pop-up and tracking. Every second bought them more time to drop their bombs before Iraqi AAA gunners could fire up their radars and get their weapons systems operational. One day in late December, Raz briefed the team that they would be targeting white bull’s-eye circles on the ground, diving in five teams of two. Shafir was paired with Yadlin. The attack profile called for Shafir to follow Yadlin at a one-second interval—or, at 360 knots, about 200 meters. The pilots fired up their engines, ran through the computerized checkoff, then lifted from the Ramat David tarmac and soared southward toward the Negev. Yadlin popped up and began his dive with Shafir just behind him and to the side. But as Yadlin reached recovery and began pulling out, Shafir was too close and the two planes headed for collision. Shafir careened radically to port, the G forces pinning him against his seat. The two F-16s streaked by each other, the air crackling in thunder. Once back at the base, Raz and Sella’s team reran the computations and quickly adjusted the profile, extending the follow-on and adding a margin of safety.