B737-800 crew had an inoperative GPS in foreign airspace.

Attributes
ACN	517709
Time
Date	200107
Day	Sun
Place
Locale Reference	atc facility : zma.artcc
State Reference	FL
Aircraft 1
Controlling Facilities	artcc : zma.artcc tracon : clt.tracon
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Navigation In Use	other
Route In Use	enroute : on vectors enroute airway : a315.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	517709
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance controller : provided flight assist none taken : anomaly accepted
Consequence	other other
Supplementary
Problem Areas	Aircraft Company
Primary Problem	Company

Narrative:

Loss of GPS. When system annunciator panel pressed the IRS and GPS lights came on indicating loss of 1 GPS. The MEL states crew placarding permitted and dispatch notification required. Additionally, 1 GPS may be inoperative for rtes where accuracy for the route can only be met by GPS and supplementary means of navigation required. I contacted dispatch, using operations person as a relay, giving details and course of action. After repeated comments, the operator said dispatch understood and I was cleared to go. In fact, the dispatcher thought I had a GPWS problem. Once airborne, I explained the situation to miami ARTCC requesting A315 with VOR navigation as a backup. Original route requiring both GPS. Simultaneously, the first officer was contacting the dispatcher with the situation. Miami ARTCC recommended radar vectors as a backup with a direct to junur intersection. Dispatch sent a message stating a communication problem with highlighting MEL requirements, and recommending A315 routing as a backup. I explained to mia the recommendations of the dispatcher and asked miami what they preferred. They wanted radar vectors probably for flow control. The dispatcher was notified of the decision to fly radar vectors. In retrospect, I believe supplementary navigation should be treated as potential lost communication necessitating vors for the B737-800.

Original NASA ASRS Text

Title: B737-800 CREW HAD AN INOP GPS IN FOREIGN AIRSPACE.

Narrative: LOSS OF GPS. WHEN SYS ANNUNCIATOR PANEL PRESSED THE IRS AND GPS LIGHTS CAME ON INDICATING LOSS OF 1 GPS. THE MEL STATES CREW PLACARDING PERMITTED AND DISPATCH NOTIFICATION REQUIRED. ADDITIONALLY, 1 GPS MAY BE INOP FOR RTES WHERE ACCURACY FOR THE RTE CAN ONLY BE MET BY GPS AND SUPPLEMENTARY MEANS OF NAV REQUIRED. I CONTACTED DISPATCH, USING OPS PERSON AS A RELAY, GIVING DETAILS AND COURSE OF ACTION. AFTER REPEATED COMMENTS, THE OPERATOR SAID DISPATCH UNDERSTOOD AND I WAS CLRED TO GO. IN FACT, THE DISPATCHER THOUGHT I HAD A GPWS PROB. ONCE AIRBORNE, I EXPLAINED THE SIT TO MIAMI ARTCC REQUESTING A315 WITH VOR NAV AS A BACKUP. ORIGINAL RTE REQUIRING BOTH GPS. SIMULTANEOUSLY, THE FO WAS CONTACTING THE DISPATCHER WITH THE SIT. MIAMI ARTCC RECOMMENDED RADAR VECTORS AS A BACKUP WITH A DIRECT TO JUNUR INTXN. DISPATCH SENT A MESSAGE STATING A COM PROB WITH HIGHLIGHTING MEL REQUIREMENTS, AND RECOMMENDING A315 ROUTING AS A BACKUP. I EXPLAINED TO MIA THE RECOMMENDATIONS OF THE DISPATCHER AND ASKED MIAMI WHAT THEY PREFERRED. THEY WANTED RADAR VECTORS PROBABLY FOR FLOW CTL. THE DISPATCHER WAS NOTIFIED OF THE DECISION TO FLY RADAR VECTORS. IN RETROSPECT, I BELIEVE SUPPLEMENTARY NAV SHOULD BE TREATED AS POTENTIAL LOST COM NECESSITATING VORS FOR THE B737-800.

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.