Airplane Navigation in Alaska?

For school I am supposed to research some navigation method used mostly in Alaska...It is either known as DABS or DBNLS...my teacher is foreign and has not been very clear...any ideas?

Airplane Navigation in Alaska?
Your teacher might be speaking of dgps.http://www.navcen.uscg.gov/dgps/default....


or ABS..see below





The United States Coast Guard (USCG) has completed installation of the Loran-C Automatic Blink System (ABS). ABS monitors Loran-C transmitting station signal timing and automatically notifies users within 2 seconds by initiating blink or taking the station off the air when signal timing exceeds a preset threshold.





The ABS timing threshold is currently set at 500 nanoseconds. USCG personnel are responsible to manually initiate blink within 60 seconds for timing errors between 100 and 500 nanoseconds from the controlling standard time difference.





ABS is now activated for all U. S. Loran stations in North America for operational testing purposes. During testing, technicians will periodically bypass the ABS at individual stations. This bypass mode deactivates the automatic user notification capability of the ABS.





Until further notice, ABS units may be in and out of the hardware bypass mode without user notification and users are cautioned to use Loran signals accordingly. No changes to Loran-C ops policy regarding ABS will be made prior to declaring ABS fully operational.





The Federal Aviation Administration will notify users when ABS transitions to ops status.


http://www.faa.gov/NTAP/NTAP07FEB15/GN01...