slant visibility[′slant ‚viz·ə′bil·əd·ē]
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The visibility from air to ground as seen by aircraft while approaching the airfield. It may be more or less than the horizontal visibility as observed from the ground. In fog and mist, the airfield may be visible from directly overhead, but the level of the fog and the mist may preclude the sighting of the aerodrome when the aircraft aligns for landing.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved