A COAST GUARD FA20 HAS AN NMAC AT 700 FT ASL WITH AN UNIDENTED HELI NOT PAINTED ON HIS TCASII 58 MI S OF PTN; LA.

Narrative

WHILE CONDUCTING A SEARCH PATTERN AT 700 FT ASL; FALCON 20 HAD A NEAR MIDAIR COLLISION WITH A HELI WHICH APPEARED TO BE A JET RANGER. COPLT MADE INTENTION CALLOUTS ON 122.8; WHICH IS 1 OF 7 OFFSHORE HELI SAFETY ADVISORY FREQS FOR THE PATTERSON AREA. TCASII DISPLAYED 1 TARGET NOT IN VISUAL CONTACT APPROX 2 O'CLOCK POS AND 3 MI. WITH NO OTHER TFC SIGHTED VISUALLY OR ON TCASII; PLT TURNED L 30-40 DEGS. WHEN LEVELING THE WINGS FROM THE TURN; PLT SAW A HELI AT THE 12 O'CLOCK POS; 3/4 MI; AND ABOUT THE SAME ALT OR SLIGHTLY LOWER. PLT IMMEDIATELY CLBED AND ESTIMATES XING OVER THE HELI WITH LESS THAN 500 FT SEPARATION. COPLT WAS LOOKING AT A CHART WHEN PLT INITIATED THE CLB; AND NEVER SAW THE HELI. TCASII CONTINUED TO DISPLAY ONLY 1 TARGET; WHICH WAS IN THE 3 O'CLOCK POS; AT 4 MI. AFTER LEVELING OFF AT 1500 FT ASL; COPLT ATTEMPTED TO CONTACT THE HELI ON THE SAFETY ADVISORY FREQ. NO COMS WERE ESTABLISHED WITH THE HELI. ANOTHER TARGET APPEARED ON TCASII IN THE POS OF THE HELI. FALCON PLTS TYPICALLY REDUCE SPD IN THESE HIGH TFC AREAS; BUT DUE TO THE LARGE SEARCH AREA AND THE CURRENT SEARCH AND RESCUE MISSION; A RISK MGMNT DECISION TO FLY NEAR MAX RANGE AIRSPD (250 KTS) WAS MADE. TCASII IS A VALUABLE SAFETY TOOL; BUT WILL NEVER SUBSTITUTE FOR LOOKING OUT THE WINDOW. HELI SAFETY GROUP SAFETY OFFICE IS IN THE PROCESS OF CONTACTING THE HELI SAFETY GROUP TO INITIATE A DISCUSSION AND POSSIBLE CHANGE TO THE PUBLISHED GULF OF MEXICO PLT INFO AND FREQ CARD. THE CURRENT CARD LISTS OVER 260 FREQS FOR BLOCK AREAS THAT ARE AS SMALL AS 5 SQUARE MI. EVEN FOR A HELI FLYING AT A RELATIVELY SLOW SPD; IT IS VERY DIFFICULT TO SWITCH BTWN FREQS AND MAKE ADVISORY CALLS FOR EVERY BLOCK TRANSITED. DISCUSSION WITH HELI SAFETY GROUP WILL ALSO INCLUDE A CALL FOR DILIGENT XPONDER USAGE. FLYING IN THE CENTRAL GULF OF MEXICO CAN BE HAZARDOUS DUE TO THE NUMEROUS PETROLEUM HELIS OPERATING OFFSHORE; BUT IS EVEN MORE HAZARDOUS IF ACFT DO NOT HAVE THEIR XPONDERS ON; IN THE CORRECT MODE; AND THE EQUIP WORKING PROPERLY.