Narrative:

Aircraft #1 was returning from a patrol mission to mfe. Aircraft #2 was on a training flight in the pattern for runway 13 at mfe. At 400 ft AGL and 1.5 NM west of the airport, aircraft #2 passed under aircraft #1 by an estimated 25 ft. Synopsis: aircraft #1 was a law enforcement helicopter returning from a patrol mission. Aircraft #2 was a rental aircraft on a training flight. The pilot of aircraft #1 had flown one other patrol mission that day and had 5.7 hours of flight time for the day. The length of aircraft #2's flight, or amount of time flown by its crew is unknown. The pilot of aircraft #1 tuned the ATIS and began monitoring mcallen tower at approximately 10 mi west of mfe. The traffic was light with an estimated 10 aircraft using mcallen's ATC services. At 6 mi west of the airport, aircraft #1 contacted mfe local control for entry into the class D airspace and landing instructions. Local control instructed the oh-6A to report 1 mi west of the airport for landing at the intersection of txwys C and C2. Just as aircraft #1 entered the class D airspace at 4 NM, aircraft #2 reported turning downwind for runway 13 at mfe. As aircraft #1 neared the airport, the pilot began clearing final for runway 13 at mfe. At the 1.5 mi west position, aircraft #1's pilot saw aircraft #2 converging from the right, or south, and at the same altitude (or nearly so). Aircraft #2 passed below aircraft #1 with approximately 25 ft of separation. The pilot of aircraft #1 tried a rapid collective only climb, but the 2 aircraft merged before the control inputs moved the helicopter. Immediately after the incident, the tower asked aircraft #1 if the pilot had the C152 in sight. Aircraft #2 reported and turned on a right base (still at 400 ft AGL) and queried local control about the traffic (aircraft #1). Aircraft #1 maneuvered to pass behind aircraft #2. Factors: 1) the pilot of aircraft #1 was not expecting, or looking for, aircraft #2 to be flying the downwind leg at 400 ft AGL. The traffic pattern altitude for mfe is published as 1107 ft MSL (1000 ft AGL). This led aircraft #1's pilot to not aggressively clear the right side, or underneath the downwind leg. 2) aircraft #2 was on a training flight with a pre-solo student and resultantly busy CFI. The CFI stated later that neither he, nor his student, saw aircraft #1 at any time during the incident. 3) the tower had a trainee controller, with instructor, working local control. During light traffic periods, the tower at mfe combines local and ground control. The traffic was high enough during this incident that the journeyman controller did not catch the trainee controller's error. The pilot of aircraft #1 spoke to the journeyman controller and the CFI onboard aircraft #2 at length concerning the incident. All parties agreed that the breakdown of vigilance caused this incident.

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Original NASA ASRS Text

Title: 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.

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.