MD550 pilot had less than legal separation with a robinson R-44 at emt, after the tower was closed.

Attributes
ACN	543063
Time
Date	200204
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : emt.airport
State Reference	CA
Altitude	msl single value : 900
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : sct.tracon tower : lax.tower
Operator	other
Make Model Name	McDonnell Douglas Helicopter Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Flight Plan	None
Aircraft 2
Controlling Facilities	tracon : sct.tracon
Operator	other
Make Model Name	Robinson R44
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Person 1
Affiliation	government other
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 126 flight time total : 3500 flight time type : 3450
ASRS Report	543063
Person 2
Affiliation	government other
Function	flight crew : single pilot
Events
Anomaly	conflict : airborne critical non adherence : required legal separation non adherence : published procedure non adherence : company policies non adherence : far other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action none taken : detected after the fact other
Miss Distance	horizontal : 500 vertical : 0
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

On 04/thu/02 at approximately XA00, I had just cleared the lax class B airspace and was en route to el monte airport for fuel at the end of a 12 hour crew day which included 7.1 hours of actual flight time. I announced my position on el monte airport unicom (tower was closed) and that I would be landing on runway 1. I activated my landing light and announced my position several times and I never heard anyone else on unicom. As I turned an approximately 1 mi final at 900 ft MSL, I noticed aircraft navigation lights at my altitude at less than 1/4 mi. I turned my aircraft to the right and apparently the other pilot turned his aircraft to the right and we passed each other at the same altitude within 500 ft horizontally of each other. I noticed that it was a government aircraft and I couldn't figure out why I never heard them on unicom. I rechked my frequency and noticed that I had incorrectly selected hawthorne unicom (121.1) instead of the correct frequency of 121.2 for el monte airport. I then called up on the correct frequency and spoke with the pilot of the other aircraft and explained the mistake I had made and why I had not called up on unicom. The lesson to be learned from this incident is to check your charts for the appropriate frequency instead of relying on memory. In addition, fatigue was probably a factor since I was at the end of my crew day and most of my flight time involved a government mission which started in indio and ended in the los angeles basin.

Original NASA ASRS Text

Title: MD550 PLT HAD LESS THAN LEGAL SEPARATION WITH A ROBINSON R-44 AT EMT, AFTER THE TWR WAS CLOSED.

Narrative: ON 04/THU/02 AT APPROX XA00, I HAD JUST CLRED THE LAX CLASS B AIRSPACE AND WAS ENRTE TO EL MONTE ARPT FOR FUEL AT THE END OF A 12 HR CREW DAY WHICH INCLUDED 7.1 HRS OF ACTUAL FLT TIME. I ANNOUNCED MY POS ON EL MONTE ARPT UNICOM (TWR WAS CLOSED) AND THAT I WOULD BE LNDG ON RWY 1. I ACTIVATED MY LNDG LIGHT AND ANNOUNCED MY POS SEVERAL TIMES AND I NEVER HEARD ANYONE ELSE ON UNICOM. AS I TURNED AN APPROX 1 MI FINAL AT 900 FT MSL, I NOTICED ACFT NAV LIGHTS AT MY ALT AT LESS THAN 1/4 MI. I TURNED MY ACFT TO THE R AND APPARENTLY THE OTHER PLT TURNED HIS ACFT TO THE R AND WE PASSED EACH OTHER AT THE SAME ALT WITHIN 500 FT HORIZLY OF EACH OTHER. I NOTICED THAT IT WAS A GOV ACFT AND I COULDN'T FIGURE OUT WHY I NEVER HEARD THEM ON UNICOM. I RECHKED MY FREQ AND NOTICED THAT I HAD INCORRECTLY SELECTED HAWTHORNE UNICOM (121.1) INSTEAD OF THE CORRECT FREQ OF 121.2 FOR EL MONTE ARPT. I THEN CALLED UP ON THE CORRECT FREQ AND SPOKE WITH THE PLT OF THE OTHER ACFT AND EXPLAINED THE MISTAKE I HAD MADE AND WHY I HAD NOT CALLED UP ON UNICOM. THE LESSON TO BE LEARNED FROM THIS INCIDENT IS TO CHK YOUR CHARTS FOR THE APPROPRIATE FREQ INSTEAD OF RELYING ON MEMORY. IN ADDITION, FATIGUE WAS PROBABLY A FACTOR SINCE I WAS AT THE END OF MY CREW DAY AND MOST OF MY FLT TIME INVOLVED A GOV MISSION WHICH STARTED IN INDIO AND ENDED IN THE LOS ANGELES BASIN.

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.