A method is disclosed for checking model planes entering into a dive, as well as an anti-dive method and apparatus. The method of checking planes includes installation of a first optical sensor in the upper part of the plane, with installation angle upwardly intersecting with the front of the plane at .alpha. degrees, that checks light intensity and outputs a first checked optical signal; installation of a second optical sensor in the bottom part of the plane, with its installation angle downwardly intersecting with the back of the plane at .beta. degrees, which checks light intensity and outputs a second checked optical signal. A comparison is made between the first and second checked optical signals, and when the difference in light intensity is smaller than a threshold, a warning signal is sent out indicating that the plane has entered into a dive.