Piel C.P. 500 tandem twin-engine light aircraft.
There are occasions when a target, though moving, does not produce a Doppler shift. An aircraft moving tangentially to the radar beam has no radial component to the radar, hence no Doppler shift. This condition is referred to as tangential fade. This condition exists only for a short period because, as the target continues moving, it will have a Doppler component away from radar and will reappear.
A condition in which a target does not appear on the radar screen when it is moving tangentially to the radar while using a moving target indicator (MTI). This phenomenon is temporary and can be overcome by canceling the MTI.