Gulfstream G500 Concludes HIRF & Lightning Tests Gulfstream recently concluded another round of tests inching the G500 program closer to certification. The latest set of tests were conducted for High Intensity Radiated Field (HIRF) and Indirect Effects of Lighting Resistance. HIRF testing assessed the aircraft’s protection to interference caused by external radio frequency (RF) signals. Testing involved placing antennas around the airframe and then transmitting RF signals ranging from 1 MHz to 18 GHz. Measurements were taken on various cable bundles and aircraft zones to characterize the aircraft’s internal HIRF environment.