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Small aircraft pilot on practice localizer approach erroneously follows false glide slope signal and descends early in VMC.
| Attributes | |
| ACN | 132012 |
| Time | |
| Date | 198912 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : apc |
| State Reference | CA |
| Altitude | msl bound lower : 1000 msl bound upper : 1800 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tower : apc |
| Operator | general aviation : personal |
| Make Model Name | Small Aircraft, Low Wing, 1 Eng, Retractable Gear |
| Flight Phase | descent : approach |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : private pilot : instrument pilot : commercial |
| Experience | flight time last 90 days : 33 flight time total : 613 flight time type : 362 |
| ASRS Report | 132012 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : published procedure other anomaly other other spatial deviation |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
I was cleared for a localizer runway 36L approach into napa county by ZOA. After intercepting the localizer I noticed my G/south indicator move to a position indicating that I was high on the G/south. I forgot that this was not an ILS, but was a localizer only approach and began to chase the G/south and descended well below the altitude specified for that segment of the approach. Fortunately the WX was clear, VMC. I certainly realize the seriousness of this mistake, especially if it were to occur in IMC. I realized that something was wrong when I went through my routine check of verifying my altitude over the OM against what is indicated on the approach plate. I now realize what a truly important check that is, and that if it is not correct, the approach should be missed immediately. In the future, I must be very careful to differentiate between localizer and ILS approachs.
Original NASA ASRS Text
Title: SMA PLT ON PRACTICE LOCALIZER APCH ERRONEOUSLY FOLLOWS FALSE GLIDE SLOPE SIGNAL AND DESCENDS EARLY IN VMC.
Narrative: I WAS CLRED FOR A LOC RWY 36L APCH INTO NAPA COUNTY BY ZOA. AFTER INTERCEPTING THE LOC I NOTICED MY G/S INDICATOR MOVE TO A POS INDICATING THAT I WAS HIGH ON THE G/S. I FORGOT THAT THIS WAS NOT AN ILS, BUT WAS A LOC ONLY APCH AND BEGAN TO CHASE THE G/S AND DSNDED WELL BELOW THE ALT SPECIFIED FOR THAT SEGMENT OF THE APCH. FORTUNATELY THE WX WAS CLEAR, VMC. I CERTAINLY REALIZE THE SERIOUSNESS OF THIS MISTAKE, ESPECIALLY IF IT WERE TO OCCUR IN IMC. I REALIZED THAT SOMETHING WAS WRONG WHEN I WENT THROUGH MY ROUTINE CHK OF VERIFYING MY ALT OVER THE OM AGAINST WHAT IS INDICATED ON THE APCH PLATE. I NOW REALIZE WHAT A TRULY IMPORTANT CHK THAT IS, AND THAT IF IT IS NOT CORRECT, THE APCH SHOULD BE MISSED IMMEDIATELY. IN THE FUTURE, I MUST BE VERY CAREFUL TO DIFFERENTIATE BTWN LOC AND ILS APCHS.
Data retrieved from NASA's ASRS site as of August 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.