just for information
only as an info on copter PIO
during my time at an army heli base i I saw a video of a Sikorsky CH-53 Copter of the Israeli Army.
The were hovering in low level and suddenly the Copter starts oscillating. I seemd as there were waves going through the airframe - until the tailbeam broke off completly.
There after the Copter became a fireball.
The vioce on the videotape told that this was an example for PIO.
mhl
kilodelta