NMAC AT 400 FT AGL BTWN POLICE ROTARY WINGED TFC AND A TRAINING C152 TURNING BASE FOR RWY 13 AT MFE; TX.

Narrative

ACFT #1 WAS RETURNING FROM A PATROL MISSION TO MFE. ACFT #2 WAS ON A TRAINING FLT IN THE PATTERN FOR RWY 13 AT MFE. AT 400 FT AGL AND 1.5 NM W OF THE ARPT; ACFT #2 PASSED UNDER ACFT #1 BY AN ESTIMATED 25 FT. SYNOPSIS: ACFT #1 WAS A LAW ENFORCEMENT HELI RETURNING FROM A PATROL MISSION. ACFT #2 WAS A RENTAL ACFT ON A TRAINING FLT. THE PLT OF ACFT #1 HAD FLOWN ONE OTHER PATROL MISSION THAT DAY AND HAD 5.7 HRS OF FLT TIME FOR THE DAY. THE LENGTH OF ACFT #2'S FLT; OR AMOUNT OF TIME FLOWN BY ITS CREW IS UNKNOWN. THE PLT OF ACFT #1 TUNED THE ATIS AND BEGAN MONITORING MCALLEN TWR AT APPROX 10 MI W OF MFE. THE TFC WAS LIGHT WITH AN ESTIMATED 10 ACFT USING MCALLEN'S ATC SVCS. AT 6 MI W OF THE ARPT; ACFT #1 CONTACTED MFE LCL CTL FOR ENTRY INTO THE CLASS D AIRSPACE AND LNDG INSTRUCTIONS. LCL CTL INSTRUCTED THE OH-6A TO RPT 1 MI W OF THE ARPT FOR LNDG AT THE INTXN OF TXWYS C AND C2. JUST AS ACFT #1 ENTERED THE CLASS D AIRSPACE AT 4 NM; ACFT #2 RPTED TURNING DOWNWIND FOR RWY 13 AT MFE. AS ACFT #1 NEARED THE ARPT; THE PLT BEGAN CLRING FINAL FOR RWY 13 AT MFE. AT THE 1.5 MI W POS; ACFT #1'S PLT SAW ACFT #2 CONVERGING FROM THE R; OR S; AND AT THE SAME ALT (OR NEARLY SO). ACFT #2 PASSED BELOW ACFT #1 WITH APPROX 25 FT OF SEPARATION. THE PLT OF ACFT #1 TRIED A RAPID COLLECTIVE ONLY CLB; BUT THE 2 ACFT MERGED BEFORE THE CTL INPUTS MOVED THE HELI. IMMEDIATELY AFTER THE INCIDENT; THE TWR ASKED ACFT #1 IF THE PLT HAD THE C152 IN SIGHT. ACFT #2 RPTED AND TURNED ON A R BASE (STILL AT 400 FT AGL) AND QUERIED LCL CTL ABOUT THE TFC (ACFT #1). ACFT #1 MANEUVERED TO PASS BEHIND ACFT #2. FACTORS: 1) THE PLT OF ACFT #1 WAS NOT EXPECTING; OR LOOKING FOR; ACFT #2 TO BE FLYING THE DOWNWIND LEG AT 400 FT AGL. THE TFC PATTERN ALT FOR MFE IS PUBLISHED AS 1107 FT MSL (1000 FT AGL). THIS LED ACFT #1'S PLT TO NOT AGGRESSIVELY CLR THE R SIDE; OR UNDERNEATH THE DOWNWIND LEG. 2) ACFT #2 WAS ON A TRAINING FLT WITH A PRE-SOLO STUDENT AND RESULTANTLY BUSY CFI. THE CFI STATED LATER THAT NEITHER HE; NOR HIS STUDENT; SAW ACFT #1 AT ANY TIME DURING THE INCIDENT. 3) THE TWR HAD A TRAINEE CTLR; WITH INSTRUCTOR; WORKING LCL CTL. DURING LIGHT TFC PERIODS; THE TWR AT MFE COMBINES LCL AND GND CTL. THE TFC WAS HIGH ENOUGH DURING THIS INCIDENT THAT THE JOURNEYMAN CTLR DID NOT CATCH THE TRAINEE CTLR'S ERROR. THE PLT OF ACFT #1 SPOKE TO THE JOURNEYMAN CTLR AND THE CFI ONBOARD ACFT #2 AT LENGTH CONCERNING THE INCIDENT. ALL PARTIES AGREED THAT THE BREAKDOWN OF VIGILANCE CAUSED THIS INCIDENT.