Narrative:

My company dispatch told me the visibility at the airport was 2 1/4 mi, when they notified me of the trip. I knew it had been foggy that night. Upon my arrival at the airport, the visibility had dropped to 1/4 mi, fog. When I started my taxi, ground control had advised us that runway 5 RVR was 1200 ft. We switched to tower and were cleared for position and hold on runway 5. Tower then called 'RVR 1000 ft cleared for takeoff.' our company's part 135 operations specifications allow reduced visibility takeoffs down to 600 ft RVR. However, for takeoff visibility less than 1/4 mi or 1200 RVR the runway must be equipped with 3 separate RVR measuring devices. Additionally, 2 out of 3 must be working and all reporting 600 ft visibility or more. My decision to takeoff compromised safety. I later found out that this runway was equipped with RVR at the touchdown area only. No RVR was available for midfield or end of runway visibility. As captain, I am responsible to know the more difficult regulations like this one. Next time I'll make a radio call to find out which visibility is being reported. A call to the control tower would have cleared up any confusion regarding which visibility was being reported. I found this information (airport RVR equipment) difficult to find in airport information pubs. I finally phoned the control tower to find out for myself. The rest of the flight was uneventful.

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Original NASA ASRS Text

Title: CAPT OF AN ATX DASSAULT FALCON, DA20, TOOK OFF BELOW MINIMUM RVR REQUIRED FOR HIS PART 135 OPS SPECS. REDUCED VISIBILITY TKOFS ARE PERMITTED PROVIDING THAT THERE ARE 3 RVR RPTING POINTS. THIS ARPT ONLY HAD THE ONE LOCATED AT THE DEP END.

Narrative: MY COMPANY DISPATCH TOLD ME THE VISIBILITY AT THE ARPT WAS 2 1/4 MI, WHEN THEY NOTIFIED ME OF THE TRIP. I KNEW IT HAD BEEN FOGGY THAT NIGHT. UPON MY ARR AT THE ARPT, THE VISIBILITY HAD DROPPED TO 1/4 MI, FOG. WHEN I STARTED MY TAXI, GND CTL HAD ADVISED US THAT RWY 5 RVR WAS 1200 FT. WE SWITCHED TO TWR AND WERE CLRED FOR POS AND HOLD ON RWY 5. TWR THEN CALLED 'RVR 1000 FT CLRED FOR TKOF.' OUR COMPANY'S PART 135 OPS SPECS ALLOW REDUCED VISIBILITY TKOFS DOWN TO 600 FT RVR. HOWEVER, FOR TKOF VISIBILITY LESS THAN 1/4 MI OR 1200 RVR THE RWY MUST BE EQUIPPED WITH 3 SEPARATE RVR MEASURING DEVICES. ADDITIONALLY, 2 OUT OF 3 MUST BE WORKING AND ALL RPTING 600 FT VISIBILITY OR MORE. MY DECISION TO TKOF COMPROMISED SAFETY. I LATER FOUND OUT THAT THIS RWY WAS EQUIPPED WITH RVR AT THE TOUCHDOWN AREA ONLY. NO RVR WAS AVAILABLE FOR MIDFIELD OR END OF RWY VISIBILITY. AS CAPT, I AM RESPONSIBLE TO KNOW THE MORE DIFFICULT REGULATIONS LIKE THIS ONE. NEXT TIME I'LL MAKE A RADIO CALL TO FIND OUT WHICH VISIBILITY IS BEING RPTED. A CALL TO THE CTL TWR WOULD HAVE CLRED UP ANY CONFUSION REGARDING WHICH VISIBILITY WAS BEING RPTED. I FOUND THIS INFO (ARPT RVR EQUIP) DIFFICULT TO FIND IN ARPT INFO PUBS. I FINALLY PHONED THE CTL TWR TO FIND OUT FOR MYSELF. THE REST OF THE FLT WAS UNEVENTFUL.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.