Navigation aid for low-visibility environments

A navigation system including two or more portable detection units, each portable detection unit being configured to be carried or worn by a user, with each portable detection unit comprising:

• a. one or more acceleration sensors, each acceleration sensor generating acceleration data representing the acceleration of the portable detection unit;
• b. one or more orientation sensors, each orientation sensor generating orientation data representing the orientation of the portable detection unit;
• c. a processor receiving the acceleration data and orientation data, and generating therefrom position data representing the position of the portable detection unit;
• d. a visual display whereupon the position data is shown;
• e. mounting means for mounting the visual display adjacent a user's head;
• and
• f. an input device in communication with the processor, wherein user actuation of the input device sets a reference location within the processor;
• with the navigation system further including a portable initialization pad separate from the portable detection units, whereby users using the portable detection units may each actuate their input devices at the initialization pad, thereby setting at least substantially the same reference location for all portable detection units.