Air ambulance has navigation system failure on overwater, non radar flight.

Attributes
ACN	232814
Time
Date	199301
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mynn
State Reference	FO
Altitude	msl bound lower : 41000 msl bound upper : 41000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zma
Operator	common carrier : air taxi
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 3000 flight time type : 750
ASRS Report	232814
Person 2
Affiliation	company : air taxi
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

We departed islip, ny, for an air ambulance trip en route to aguadilla, pr. After being vectored, we were cleared direct to champ intersection, then to proceed flight planned route, which was A300 to pling intersection, then direct aguadilla. We navigated using our GNS, which seemed to be performing normally. The only unusual indication was that the winds on the GNS were higher than those forecast. Shortly after crossing elwod intersection, we were advised by commercial radio to contact ZMA, who advised us that we were in radar contact 180 mi northeast of nassau. At this point, we were given a vector towards grand turk VOR and reclred to aguadilla. We proceeded to the destination without incident. Before departing aguadilla, we re-filed for an inland route that would keep us in radar contact. I placarded the GNS inoperative in accordance with our MEL and returned the patient to islip without incident. The director of maintenance felt that the malfunction may have been caused by a temporary blockage in one of the GNS unit's static sources. One suggestion for preventing such an event might be to require 2 long range navigation system whenever operating out of radar contact.

Original NASA ASRS Text

Title: AIR AMBULANCE HAS NAV SYS FAILURE ON OVERWATER, NON RADAR FLT.

Narrative: WE DEPARTED ISLIP, NY, FOR AN AIR AMBULANCE TRIP ENRTE TO AGUADILLA, PR. AFTER BEING VECTORED, WE WERE CLRED DIRECT TO CHAMP INTXN, THEN TO PROCEED FLT PLANNED RTE, WHICH WAS A300 TO PLING INTXN, THEN DIRECT AGUADILLA. WE NAVIGATED USING OUR GNS, WHICH SEEMED TO BE PERFORMING NORMALLY. THE ONLY UNUSUAL INDICATION WAS THAT THE WINDS ON THE GNS WERE HIGHER THAN THOSE FORECAST. SHORTLY AFTER XING ELWOD INTXN, WE WERE ADVISED BY COMMERCIAL RADIO TO CONTACT ZMA, WHO ADVISED US THAT WE WERE IN RADAR CONTACT 180 MI NE OF NASSAU. AT THIS POINT, WE WERE GIVEN A VECTOR TOWARDS GRAND TURK VOR AND RECLRED TO AGUADILLA. WE PROCEEDED TO THE DEST WITHOUT INCIDENT. BEFORE DEPARTING AGUADILLA, WE RE-FILED FOR AN INLAND RTE THAT WOULD KEEP US IN RADAR CONTACT. I PLACARDED THE GNS INOP IN ACCORDANCE WITH OUR MEL AND RETURNED THE PATIENT TO ISLIP WITHOUT INCIDENT. THE DIRECTOR OF MAINT FELT THAT THE MALFUNCTION MAY HAVE BEEN CAUSED BY A TEMPORARY BLOCKAGE IN ONE OF THE GNS UNIT'S STATIC SOURCES. ONE SUGGESTION FOR PREVENTING SUCH AN EVENT MIGHT BE TO REQUIRE 2 LONG RANGE NAV SYS WHENEVER OPERATING OUT OF RADAR CONTACT.

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.