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A320 pilot received a low altitude alert and was confused with phraseology used by ATC concerning the status of the ILS GS glide path.
| Attributes | |
| ACN | 533823 |
| Time | |
| Date | 200112 |
| Day | Sat |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : msp.airport |
| State Reference | MN |
| Altitude | msl bound lower : 2000 msl bound upper : 2400 |
| Environment | |
| Flight Conditions | IMC |
| Weather Elements | Rain |
| Light | Dusk |
| Aircraft 1 | |
| Controlling Facilities | tracon : m98.tracon tower : msp.tower |
| Operator | common carrier : air carrier |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | ils localizer & glide slope : 12r other |
| Flight Phase | descent : approach |
| Route In Use | approach : instrument precision |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : multi engine pilot : instrument pilot : flight engineer pilot : commercial pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 250 flight time total : 15000 flight time type : 5000 |
| ASRS Report | 533823 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | altitude deviation : overshoot inflight encounter : weather non adherence : published procedure other spatial deviation |
| Independent Detector | other controllera other flight crewa other flight crewb |
| Resolutory Action | controller : issued alert flight crew : became reoriented flight crew : exited adverse environment |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance ATC Human Performance |
| Primary Problem | Flight Crew Human Performance |
Narrative:
We crossed kinns FAF for ILS runway 12R at msp on GS at published altitude of 2765 ft. Shortly inside marker, the GS became unstable. WX reported as 1800 ft 4 DME, was actually more like 1400 ft 2 DME. We ended up below glide path and generated an ATC alert for us to check altitude. By this time, we had ground contact and proceeded visually to airport. This approach has NOTAMS for GS reliability to this runway due to the ILS beam not being protected from ground traffic. The ATIS at the time showed the ILS approach in use, with the GS unreliable. How can an ILS approach be issued without a reliable GS? Numerous aircraft reported similar problems with GS as we did.
Original NASA ASRS Text
Title: A320 PLT RECEIVED A LOW ALT ALERT AND WAS CONFUSED WITH PHRASEOLOGY USED BY ATC CONCERNING THE STATUS OF THE ILS GS GLIDE PATH.
Narrative: WE CROSSED KINNS FAF FOR ILS RWY 12R AT MSP ON GS AT PUBLISHED ALT OF 2765 FT. SHORTLY INSIDE MARKER, THE GS BECAME UNSTABLE. WX RPTED AS 1800 FT 4 DME, WAS ACTUALLY MORE LIKE 1400 FT 2 DME. WE ENDED UP BELOW GLIDE PATH AND GENERATED AN ATC ALERT FOR US TO CHK ALT. BY THIS TIME, WE HAD GND CONTACT AND PROCEEDED VISUALLY TO ARPT. THIS APCH HAS NOTAMS FOR GS RELIABILITY TO THIS RWY DUE TO THE ILS BEAM NOT BEING PROTECTED FROM GND TFC. THE ATIS AT THE TIME SHOWED THE ILS APCH IN USE, WITH THE GS UNRELIABLE. HOW CAN AN ILS APCH BE ISSUED WITHOUT A RELIABLE GS? NUMEROUS ACFT RPTED SIMILAR PROBS WITH GS AS WE DID.
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.