MSAW activated by commuter light transport on localizer approach to mke.

Attributes
ACN	133993
Time
Date	199001
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mke
State Reference	WI
Altitude	msl bound lower : 1400 msl bound upper : 1500
Environment
Flight Conditions	IMC
Light	Dawn
Aircraft 1
Controlling Facilities	tower : mke
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	descent : approach landing other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 270 flight time total : 3300
ASRS Report	133993
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : crossing restriction not met non adherence : published procedure non adherence : clearance other spatial deviation
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On the approach into mke (localizer 19R G/south OTS), flight was cleared for the approach. After crossing the FAF (yanks) we began our descent to the step-down altitude 1500' MSL to maintain 1500' until crossing the bayze fix (a step-down fix). This fix is formed off the localizer 19R and the 138 degree right off timmerman VOR 112.5. Once crossing bayze we began our descent down to the MDA 1160' MSL. At approximately 1400' MSL tower advised us that we were below the step-down altitude and were still 1 mi north of bayze. At this time, we climbed to 1500' MSL and checked the position of the aft. We showed that we had already crossed bayze and we continued down to 1160' MDA. At this time we had the runway in sight and had already been cleared to land, so we landed the aircraft on 19R. The WX was M9 overcast 4RW-F 092/50/49/2110/979. I feel that the only problem in this situation was the discrepancy between radar's position and the crossing radials ability to identify bayze. Next time I will always ask for a radar identify to verify our position before descent.

Original NASA ASRS Text

Title: MSAW ACTIVATED BY COMMUTER LTT ON LOCALIZER APCH TO MKE.

Narrative: ON THE APCH INTO MKE (LOC 19R G/S OTS), FLT WAS CLRED FOR THE APCH. AFTER XING THE FAF (YANKS) WE BEGAN OUR DSCNT TO THE STEP-DOWN ALT 1500' MSL TO MAINTAIN 1500' UNTIL XING THE BAYZE FIX (A STEP-DOWN FIX). THIS FIX IS FORMED OFF THE LOC 19R AND THE 138 DEG R OFF TIMMERMAN VOR 112.5. ONCE XING BAYZE WE BEGAN OUR DSCNT DOWN TO THE MDA 1160' MSL. AT APPROX 1400' MSL TWR ADVISED US THAT WE WERE BELOW THE STEP-DOWN ALT AND WERE STILL 1 MI N OF BAYZE. AT THIS TIME, WE CLBED TO 1500' MSL AND CHKED THE POS OF THE AFT. WE SHOWED THAT WE HAD ALREADY CROSSED BAYZE AND WE CONTINUED DOWN TO 1160' MDA. AT THIS TIME WE HAD THE RWY IN SIGHT AND HAD ALREADY BEEN CLRED TO LAND, SO WE LANDED THE ACFT ON 19R. THE WX WAS M9 OVCST 4RW-F 092/50/49/2110/979. I FEEL THAT THE ONLY PROB IN THIS SITUATION WAS THE DISCREPANCY BTWN RADAR'S POS AND THE XING RADIALS ABILITY TO IDENT BAYZE. NEXT TIME I WILL ALWAYS ASK FOR A RADAR IDENT TO VERIFY OUR POS BEFORE DSCNT.

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.