When English speaking people say "we dove on it," it means "we grabbed (or got to it) quickly." For example, if someone comes up with a good idea, one can "dive on it," meaning take that idea and turn it immediately into profitable action. In this case of the film you were watching, it could mean two things: 1.) Since the person is a pilot, if they were actually a plane in the sky during this scene, they could literally mean that they "dove" the plane in that direction toward the UFO to check it out. 2.) It could also mean that the pilot realized that they had discovered a UFO and wanted to make sure that they received credit for the discovery, thus they "dove on it," in example, took whatever means necessary to prove it that it was indeed a UFO and that they were the first ones to see it. For example, here: https://www.merriam-webster.com/dictionary/dive Option 2c is #1 above. Option 3a is #2 above. I hope this helps!