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punkalouver · 14th September 2008, 05:55

Some details are here in AIC 7/08

http://www.navcanada.ca/ContentDefin...c/5aic_eng.pdf

and here.

OCAS system

I see the OCAS system says "the pilot is warned by either flashing lights AND/OR aural warning transmitted over THE VHF band",

while the Whistler site says "If a collision hazard exists, the pilot is warned by flashing high intensity strobe lights AND an audible warning transmitted over ALL aircraft radio frequencies.",

while the AIC from the government says "The system detects aircraft on any track that may conflict within five nautical miles (NM) from the surface to 165 feet above the obstacle. The system's first warning is the activation of white strobe lights, 30 seconds prior to conflict. These strobes are medium intensity during the day and low intensity at night. The second warning, 20 seconds prior to conflict, consists of an audio message transmitted on PRE-SELECTED VHF frequencies stating "POWER LINE, POWER LINE" or whatever type of obstruction is applicable. The timing of each warning can be modified as required by the approving authority."

I would suspect that the last one is the most accurate. What these preselected frequencies are is a mystery but if I had to guess, I would say 126.7 and 121.5. The OCAS website shows two other installations in Canada in B.C.

14th September 2008, 05:55	#2 (permalink)
punkalouver Join Date: Nov 2004 Location: Here, there, and everywhere Posts: 381	Some details are here in AIC 7/08 http://www.navcanada.ca/ContentDefin...c/5aic_eng.pdf and here. OCAS system I see the OCAS system says "the pilot is warned by either flashing lights AND/OR aural warning transmitted over THE VHF band", while the Whistler site says "If a collision hazard exists, the pilot is warned by flashing high intensity strobe lights AND an audible warning transmitted over ALL aircraft radio frequencies.", while the AIC from the government says "The system detects aircraft on any track that may conflict within five nautical miles (NM) from the surface to 165 feet above the obstacle. The system's first warning is the activation of white strobe lights, 30 seconds prior to conflict. These strobes are medium intensity during the day and low intensity at night. The second warning, 20 seconds prior to conflict, consists of an audio message transmitted on PRE-SELECTED VHF frequencies stating "POWER LINE, POWER LINE" or whatever type of obstruction is applicable. The timing of each warning can be modified as required by the approving authority." I would suspect that the last one is the most accurate. What these preselected frequencies are is a mystery but if I had to guess, I would say 126.7 and 121.5. The OCAS website shows two other installations in Canada in B.C.