GLF2 flight crew has navigation 1 and 2 fail to connect properly to the HSI; resulting in a faulty l...

Attributes
ACN	790009
Time
Date	200806
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 3000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : aex.tower
Operator	general aviation : personal
Make Model Name	Gulfstream II
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : multi engine pilot : instrument pilot : atp pilot : cfi
ASRS Report	790009
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : less severe non adherence : published procedure
Independent Detector	other flight crewa
Resolutory Action	controller : provided flight assist controller : issued new clearance flight crew : diverted to another airport flight crew : executed missed approach
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

In IMC; we were assigned to intercept and track inbound on the ZZZ runway xxl localizer. At approximately 19 DME we began to notice a swing on the localizer needle on the obs. We questioned the approach controller on any previously reported localizer swings. Approach and another aircraft reported that there were no observed localizer swings. We asked our position; were told that we were 2 degrees off runway xxl localizer. After being cleared for the ILS runway xxl and intercepting the GS; the captain's obs with GS and localizer information failed. We notified ATC and initiated a missed approach. We had no guidance from the navigation #1 and #2 and had to fly radar vectors to VMC. Not knowing what had caused the navigation failure; we climbed out at 500 FPM. Once in VMC; we were handed off to socal for vectors to an airport (ZZZ1) in VMC. During the process; we were unable to 'back up the approach' with the FMS as it does not have ILS capabilities (honeywell GNS xls). It took some time in VMC to determine that there was a failure of the #1 and #2 navigation connection to the HSI. Once connected to the FMS; we were able to navigation in 'VMC on top.' outstanding help from ATC!

Original NASA ASRS Text

Title: GLF2 FLT CREW HAS NAV 1 AND 2 FAIL TO CONNECT PROPERLY TO THE HSI; RESULTING IN A FAULTY LOC SIGNAL AND A SUBSEQUENT MISSED APPROACH.

Narrative: IN IMC; WE WERE ASSIGNED TO INTERCEPT AND TRACK INBOUND ON THE ZZZ RWY XXL LOC. AT APPROX 19 DME WE BEGAN TO NOTICE A SWING ON THE LOC NEEDLE ON THE OBS. WE QUESTIONED THE APCH CTLR ON ANY PREVIOUSLY RPTED LOC SWINGS. APCH AND ANOTHER ACFT RPTED THAT THERE WERE NO OBSERVED LOC SWINGS. WE ASKED OUR POS; WERE TOLD THAT WE WERE 2 DEGS OFF RWY XXL LOC. AFTER BEING CLRED FOR THE ILS RWY XXL AND INTERCEPTING THE GS; THE CAPT'S OBS WITH GS AND LOC INFO FAILED. WE NOTIFIED ATC AND INITIATED A MISSED APCH. WE HAD NO GUIDANCE FROM THE NAV #1 AND #2 AND HAD TO FLY RADAR VECTORS TO VMC. NOT KNOWING WHAT HAD CAUSED THE NAV FAILURE; WE CLBED OUT AT 500 FPM. ONCE IN VMC; WE WERE HANDED OFF TO SOCAL FOR VECTORS TO AN ARPT (ZZZ1) IN VMC. DURING THE PROCESS; WE WERE UNABLE TO 'BACK UP THE APCH' WITH THE FMS AS IT DOES NOT HAVE ILS CAPABILITIES (HONEYWELL GNS XLS). IT TOOK SOME TIME IN VMC TO DETERMINE THAT THERE WAS A FAILURE OF THE #1 AND #2 NAV CONNECTION TO THE HSI. ONCE CONNECTED TO THE FMS; WE WERE ABLE TO NAV IN 'VMC ON TOP.' OUTSTANDING HELP FROM ATC!

Data retrieved from NASA's ASRS site as of May 2009 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.

GLF2 flight crew has navigation 1 and 2 fail to connect properly to the HSI; resulting in a faulty localizer signal and a subsequent missed approach.