"航向改变角" can be translated as "course change angle" or "heading change angle" in English.
"Course" typically refers to the intended path or direction of travel of a vessel or aircraft, while "heading" refers to the actual direction in which the vessel or aircraft is pointing at any given moment.
In many contexts, especially in navigation and aviation, these two terms can be used interchangeably when referring to the angle by which the direction of travel is changed, so both "course change angle" and "heading change angle" are acceptable translations.