The articles presents issues related to ultrasonic testing of welded joints and includes results of tests dedicated to the detectability of flat discontinuities depending on their orientation in relation to the ultrasonic beam axis. In the tests, flat discontinuities were constituted by circular flat-bottomed reflectors of DGS-45° standard having a diameter D_DSR=2 mm. The tests were performed using a Phased Array transducer and a defectoscope with a Phased Array imaging package enabling the determination of echo amplitude for various beam insertion angle values. As a result, it was possible to obtain the characteristics of a decibel echo drop depending on the beam angle of incidence on the flat-bottomed reflector in a range from the optimum to a disadvantageous value. The article includes a diagram “distance – amplification - beam angle of incidence on the reflector” enabling the determination of an echo amplitude drop accompanying the changes of angles at which the beam strikes a discontinuity by 5°, 10° and 15°.