Abstract: An apparatus for detecting leakages in structural members (8) is disclosed. The apparatus includes a device (2) for conveying gas through the structural member (8) to be investigated, a camera (14) having a narrow band filter characteristic matched to the spectral absorption of the gas and a device (16, 18) connected to the camera (14) for processing and displaying the recorded image of the structural member (8) to be investigated.

Abstract: The aircraft is provided with an infrared sensor which is adjustable by means of feedback control so that its line of sight (image center) is and remains in line with the middle one of three infrared fires at and near the end of the runway. The craft is now maneuvered in such a way that its longitudinal axis is aligned with the horizontal component of the line of sight. After a particular distance has been reached, the aircraft descends while the image of the middle fire remains centered. The system uses existing equipment and is further supplemented to correct an initial gross deviation from the desired approach path.