MD80 captain wonders whether his after market gfms can be used to identify fixes on approachs.

Attributes
ACN	584822
Time
Date	200306
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : san.airport
State Reference	CA
Altitude	msl bound lower : 1650 msl bound upper : 2000
Environment
Light	Night
Aircraft 1
Controlling Facilities	tower : san.tower
Operator	common carrier : air carrier
Make Model Name	MD-80 Super 80
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer only : 27 other other other vortac
Flight Phase	descent : approach
Route In Use	approach : instrument non precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	584822
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	altitude deviation : excursion from assigned altitude altitude deviation : crossing restriction not met altitude deviation : overshoot non adherence : clearance non adherence : company policies non adherence : far non adherence : published procedure other anomaly other
Independent Detector	atc equipment : msaw other controllera
Resolutory Action	controller : issued alert flight crew : returned to assigned altitude
Consequence	other
Supplementary
Problem Areas	Navigational Facility Aircraft Company Flight Crew Human Performance
Primary Problem	Company
Air Traffic Incident	Pilot Deviation

Narrative:

In reviewing localizer runway 27 approach to san, found the DME to runway 27 notamed OTS. In discussion about identing the various intxns without the use of the DME, tried to find in the book where we could use the gfms to identify the fixes instead of raw data. Could not find that anywhere. Used the radials of poggi VOR to identify swatt and reebo intxns and used time for missed approach point. Using poggi 304 degree radial, I started down out of 2000 ft MSL. Gfms indicated that we were almost .5 mi from reebo intersection. Tower called and said 'altitude alert, check your altitude. Need to cross reebo at 2000 ft MSL.' at that point, I was at 1650 ft MSL. I leveled for just a few seconds until the gfms indicated that we were past reebo and continued approach. A couple of questions arise here. First, if it is legal to use gfms to identify intxns, why isn't it in the book instead of some obscure advisory circular? Book is very vague on using gfms for navigation on localizer, ILS, localizer back course, lda and sdf. It suggests it cannot be used for navigation period. Says nothing about using it to identify intxns. This needs to be cleared up. I just got out of training and this was brought up but about how this needs to be changed. Don't think ATC had a problem, wanted to send this in case.

Original NASA ASRS Text

Title: MD80 CAPT WONDERS WHETHER HIS AFTER MARKET GFMS CAN BE USED TO IDENT FIXES ON APCHS.

Narrative: IN REVIEWING LOC RWY 27 APCH TO SAN, FOUND THE DME TO RWY 27 NOTAMED OTS. IN DISCUSSION ABOUT IDENTING THE VARIOUS INTXNS WITHOUT THE USE OF THE DME, TRIED TO FIND IN THE BOOK WHERE WE COULD USE THE GFMS TO IDENT THE FIXES INSTEAD OF RAW DATA. COULD NOT FIND THAT ANYWHERE. USED THE RADIALS OF POGGI VOR TO IDENT SWATT AND REEBO INTXNS AND USED TIME FOR MISSED APCH POINT. USING POGGI 304 DEG RADIAL, I STARTED DOWN OUT OF 2000 FT MSL. GFMS INDICATED THAT WE WERE ALMOST .5 MI FROM REEBO INTXN. TWR CALLED AND SAID 'ALT ALERT, CHK YOUR ALT. NEED TO CROSS REEBO AT 2000 FT MSL.' AT THAT POINT, I WAS AT 1650 FT MSL. I LEVELED FOR JUST A FEW SECONDS UNTIL THE GFMS INDICATED THAT WE WERE PAST REEBO AND CONTINUED APCH. A COUPLE OF QUESTIONS ARISE HERE. FIRST, IF IT IS LEGAL TO USE GFMS TO IDENT INTXNS, WHY ISN'T IT IN THE BOOK INSTEAD OF SOME OBSCURE ADVISORY CIRCULAR? BOOK IS VERY VAGUE ON USING GFMS FOR NAV ON LOC, ILS, LOC BACK COURSE, LDA AND SDF. IT SUGGESTS IT CANNOT BE USED FOR NAV PERIOD. SAYS NOTHING ABOUT USING IT TO IDENT INTXNS. THIS NEEDS TO BE CLRED UP. I JUST GOT OUT OF TRAINING AND THIS WAS BROUGHT UP BUT ABOUT HOW THIS NEEDS TO BE CHANGED. DON'T THINK ATC HAD A PROB, WANTED TO SEND THIS IN CASE.

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.