MD80 flight crew reports GPS signal loss near krost as notamed and the inability of the non DME/DME ...

Attributes
ACN	774166
Time
Date	200802
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : mod.vor
State Reference	CA
Altitude	msl single value : 32000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zoa.artcc artcc : zlc.artcc
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	774166
Events
Anomaly	non adherence : clearance other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance controller : issued advisory none taken : anomaly accepted
Supplementary
Problem Areas	Navigational Facility Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Saw on paperwork the NOTAM for a possible GPS outage near the tonopah test range. Knew that we were filed north of that (bce-ilc-oal-inyoe-trose-mod) and did not situation down and determine how far north (had a 25 min turn with a plane change and concourse change). Approaching ilc; we were given ilc-krost-oal as filed for military airspace. Approaching krost; the FMS went into dead reckoning with no satellite signals being received at all. We dialed in oal and started tracking the VOR. At this time we entered the latitude/longitude for the outage center and saw that we were about 70 mi away. My guess is the outage radius at our altitude was about 150 mi. After informing ZLC that we had lost our GPS signal; we were switched to ZOA who then cleared us direct mod. Dialed that in and started receiving a weak signal at about 150 DME. The radial showed us tracking south of course; so I added in additional right correction. At about 110 DME the needle showed centered; and the satellites came back online; showing us well north of the direct line to mod. At that same moment; oak asked where we were tracking and we once again stated that the GPS signal had been lost but had now been reacquired and we were going direct mod. These FMS aircraft without DME/DME update capability should not be sent on this routing in the evening while the military is playing with the satellite signal! The dr ability of this box is non-existent. The VOR signals are not good enough around the mountains to be given off-course routings in this situation.

Original NASA ASRS Text

Title: MD80 FLT CREW REPORTS GPS SIGNAL LOSS NEAR KROST AS NOTAMED AND THE INABILITY OF THE NON DME/DME ACFT TO NAVIGATE SUCCESSFULLY DURING THE OUTAGE.

Narrative: SAW ON PAPERWORK THE NOTAM FOR A POSSIBLE GPS OUTAGE NEAR THE TONOPAH TEST RANGE. KNEW THAT WE WERE FILED N OF THAT (BCE-ILC-OAL-INYOE-TROSE-MOD) AND DID NOT SIT DOWN AND DETERMINE HOW FAR N (HAD A 25 MIN TURN WITH A PLANE CHANGE AND CONCOURSE CHANGE). APCHING ILC; WE WERE GIVEN ILC-KROST-OAL AS FILED FOR MIL AIRSPACE. APCHING KROST; THE FMS WENT INTO DEAD RECKONING WITH NO SATELLITE SIGNALS BEING RECEIVED AT ALL. WE DIALED IN OAL AND STARTED TRACKING THE VOR. AT THIS TIME WE ENTERED THE LAT/LONGITUDE FOR THE OUTAGE CTR AND SAW THAT WE WERE ABOUT 70 MI AWAY. MY GUESS IS THE OUTAGE RADIUS AT OUR ALT WAS ABOUT 150 MI. AFTER INFORMING ZLC THAT WE HAD LOST OUR GPS SIGNAL; WE WERE SWITCHED TO ZOA WHO THEN CLRED US DIRECT MOD. DIALED THAT IN AND STARTED RECEIVING A WEAK SIGNAL AT ABOUT 150 DME. THE RADIAL SHOWED US TRACKING S OF COURSE; SO I ADDED IN ADDITIONAL R CORRECTION. AT ABOUT 110 DME THE NEEDLE SHOWED CTRED; AND THE SATELLITES CAME BACK ONLINE; SHOWING US WELL N OF THE DIRECT LINE TO MOD. AT THAT SAME MOMENT; OAK ASKED WHERE WE WERE TRACKING AND WE ONCE AGAIN STATED THAT THE GPS SIGNAL HAD BEEN LOST BUT HAD NOW BEEN REACQUIRED AND WE WERE GOING DIRECT MOD. THESE FMS ACFT WITHOUT DME/DME UPDATE CAPABILITY SHOULD NOT BE SENT ON THIS ROUTING IN THE EVENING WHILE THE MIL IS PLAYING WITH THE SATELLITE SIGNAL! THE DR ABILITY OF THIS BOX IS NON-EXISTENT. THE VOR SIGNALS ARE NOT GOOD ENOUGH AROUND THE MOUNTAINS TO BE GIVEN OFF-COURSE ROUTINGS IN THIS SITUATION.

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.

MD80 flight crew reports GPS signal loss near krost as notamed and the inability of the non DME/DME aircraft to navigate successfully during the outage.