The former now maintains a navigation aid, while the latter does not.

They also act as a navigation aid by providing an overview of a site's content at a single glance.

The lit sign atop the building served sailors as a navigation aid for many years.

Using this as a navigation aid, it is possible to move boxers 360 degrees around the ring.

BW-3 became an essential navigation aid for ships and aircraft.

They were fishing for trepang and appeared to have only a small compass as a navigation aid.

Constitute a comprehensive table of contents and provide corresponding navigation aid.

It was formerly used as a navigation aid for ships.

The sign serves more as a navigation aid for tourists.

I was still racking my brain for some sort of navigation aid.