In a video cassette recorder, the flying erase head is a feature that may be found in some high-end home VCRs as well as some broadcast-grade VCRs to cleanly edit the video.
Normally, the tape is passed longitudinally through two fixed erase heads, one located just before the tape moves to the video head drum and the other right next to the audio/control head stack. Upon recording, the erase heads erase any old recording contained on the tape to prevent anything already recorded on it from interfering with what is being recorded.
However, when trying to edit footage deck to deck, portions of the old recording's video may be between the erase head and video recording heads. This results in a faint rainbow-like noise at and briefly after the point of the cut as the old video recording missed by the fixed erase head is never completely erased as the new recording is printed.
The flying erase head is so-called because an erase head is mounted on the video head drum and rotates around in the same manner as the video heads. In the record mode, the erase head is active and erases the video precisely down to the recorded video fields. The flying erase head runs over the tape and the video heads record the signal virtually instantly after the flying erase head has passed.
Since the erase head erases the old signal right before the video heads write onto the tape, there is no remnant of the old signal to cause visible distortion at and after the moment a cut is made, resulting in a clean edit. In addition, the ability of flying erase heads to erase old video off the tape right before recording new video on it allows the ability to perform insert editing, where new footage can be placed within an existing recording with clean cuts at the beginning and end of the edit.