Near midair collision - a twin otter flies closely beneath a helicopter overwater in hawaii.

Attributes
ACN	299350
Time
Date	199503
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ogg
State Reference	HI
Altitude	msl bound lower : 1350 msl bound upper : 1350
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : jhm tracon : ogg
Operator	common carrier : air taxi
Make Model Name	MD Helicopter 500/C/D/E/L
Operating Under FAR Part	Part 135
Flight Phase	cruise other
Route In Use	enroute airway : ogg
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air taxi
Make Model Name	Twin Otter DHC-6
Operating Under FAR Part	Part 135
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air taxi
Function	flight crew : single pilot
Qualification	pilot : atp
Experience	flight time last 90 days : 300 flight time total : 3700
ASRS Report	299350
Person 2
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac non adherence : far other anomaly other
Independent Detector	other flight crewa other other : unspecified
Resolutory Action	none taken : detected after the fact
Consequence	Other
Miss Distance	horizontal : 0 vertical : 100
Supplementary
Primary Problem	Flight Crew Human Performance
Situations
ATC Facility	other physical facility

Narrative:

A twin otter passed 100 ft beneath me in a near miss on a heading of 150 degrees. I was in a hughes 500D mid channel between the island of molokai and maui on a heading of 300 degree 5 NM from nakalele point. I was level at 1350 ft and he was climbing slightly. Action taken: 1) I was on radar advisories with departure control on 120.2 and immediately notified them of a twin otter passing closely under me and asked if they showed another aircraft in my vicinity, they did not. 2) no evasive action was taken on my part. I sighted the twin otter 1 second before crossing and had no time to react. I believe the situation (near miss) occurred because: 1) 2 aircraft were in the same vicinity talking on different frequencys . One of the aircraft receiving radar advisories in an area where the service may be difficult to provide. My suggestion on how to prevent a recurrence is to keep aircraft on same frequency in same vicinity. If adequate radar services can't be provided, then use only kapalua's frequency 120.7 beyond nakalele point wbound.

Original NASA ASRS Text

Title: NMAC - A TWIN OTTER FLIES CLOSELY BENEATH A HELI OVERWATER IN HAWAII.

Narrative: A TWIN OTTER PASSED 100 FT BENEATH ME IN A NEAR MISS ON A HDG OF 150 DEGS. I WAS IN A HUGHES 500D MID CHANNEL BTWN THE ISLAND OF MOLOKAI AND MAUI ON A HDG OF 300 DEG 5 NM FROM NAKALELE POINT. I WAS LEVEL AT 1350 FT AND HE WAS CLBING SLIGHTLY. ACTION TAKEN: 1) I WAS ON RADAR ADVISORIES WITH DEP CTL ON 120.2 AND IMMEDIATELY NOTIFIED THEM OF A TWIN OTTER PASSING CLOSELY UNDER ME AND ASKED IF THEY SHOWED ANOTHER ACFT IN MY VICINITY, THEY DID NOT. 2) NO EVASIVE ACTION WAS TAKEN ON MY PART. I SIGHTED THE TWIN OTTER 1 SECOND BEFORE XING AND HAD NO TIME TO REACT. I BELIEVE THE SIT (NEAR MISS) OCCURRED BECAUSE: 1) 2 ACFT WERE IN THE SAME VICINITY TALKING ON DIFFERENT FREQS . ONE OF THE ACFT RECEIVING RADAR ADVISORIES IN AN AREA WHERE THE SERVICE MAY BE DIFFICULT TO PROVIDE. MY SUGGESTION ON HOW TO PREVENT A RECURRENCE IS TO KEEP ACFT ON SAME FREQ IN SAME VICINITY. IF ADEQUATE RADAR SERVICES CAN'T BE PROVIDED, THEN USE ONLY KAPALUA'S FREQ 120.7 BEYOND NAKALELE POINT WBOUND.

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.