An image data correction method includes preparing correction data for correcting a distortion of an image obtained by an image acquiring section, acquiring outline data of a desired pattern obtained by the image acquiring section, and correcting the outline data of the desired pattern using the correction data. Components include multiple, discrete features that extend laterally from a common side of an upper end of a formation, for engagement of loops. The example apparatus also includes a sensor array disposed on the aircraft to acquire information related to the gaseous packet.