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B737 on ILS approach to mggt encounters fluctuating, weak GS signal that causes equipment pitch up, pitch down.
| Attributes | |
| ACN | 511697 |
| Time | |
| Date | 200105 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : mggt.airport |
| State Reference | FO |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | ils localizer & glide slope : 01 |
| 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 |
| ASRS Report | 511697 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | aircraft equipment problem : less severe |
| Independent Detector | aircraft equipment other aircraft equipment : gs other flight crewa |
| Resolutory Action | flight crew : overrode automation flight crew : became reoriented |
| Consequence | other |
| Supplementary | |
| Problem Areas | Navigational Facility Airport |
| Primary Problem | Navigational Facility |
| Situations | |
| Airport | other physical facility |
Narrative:
When capturing the GS for ILS runway 1 at gua, the aircraft will pitch up and down. I would approximate the pitch as 10 degrees. I am not sure if it is a weak GS signal or something else that may cause it. It happens when flying the ILS and doing the arc approach or the ILS DME 1 or 2. Callback conversation with reporter revealed the following information: reporter has concerns with mggt equipment reliability. A report has been referred to company to attempt to determine if it was attributed to the aircraft equipment or associated with mggt ILS ground equipment. A company equipment specialist advised that the ILS equipment problem has been referred to mggt airport officials, also, that another air carrier has coordination to mggt their flight operations concerns. An mggt official has recently advised that a wire mesh fence around that portion of the airport has been moved out another 30 meters. Since then, flcs have still noted small fluctuations. The company specialist stated that a request has been made to mggt airport for a government flight check to validate the ILS equipment is operating within specifications. Until that report is received, the air carrier has implemented additional WX restrs for flight operations.
Original NASA ASRS Text
Title: B737 ON ILS APCH TO MGGT ENCOUNTERS FLUCTUATING, WEAK GS SIGNAL THAT CAUSES EQUIP PITCH UP, PITCH DOWN.
Narrative: WHEN CAPTURING THE GS FOR ILS RWY 1 AT GUA, THE ACFT WILL PITCH UP AND DOWN. I WOULD APPROXIMATE THE PITCH AS 10 DEGS. I AM NOT SURE IF IT IS A WEAK GS SIGNAL OR SOMETHING ELSE THAT MAY CAUSE IT. IT HAPPENS WHEN FLYING THE ILS AND DOING THE ARC APCH OR THE ILS DME 1 OR 2. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR HAS CONCERNS WITH MGGT EQUIP RELIABILITY. A RPT HAS BEEN REFERRED TO COMPANY TO ATTEMPT TO DETERMINE IF IT WAS ATTRIBUTED TO THE ACFT EQUIP OR ASSOCIATED WITH MGGT ILS GND EQUIP. A COMPANY EQUIP SPECIALIST ADVISED THAT THE ILS EQUIP PROB HAS BEEN REFERRED TO MGGT ARPT OFFICIALS, ALSO, THAT ANOTHER ACR HAS COORD TO MGGT THEIR FLT OPS CONCERNS. AN MGGT OFFICIAL HAS RECENTLY ADVISED THAT A WIRE MESH FENCE AROUND THAT PORTION OF THE ARPT HAS BEEN MOVED OUT ANOTHER 30 METERS. SINCE THEN, FLCS HAVE STILL NOTED SMALL FLUCTUATIONS. THE COMPANY SPECIALIST STATED THAT A REQUEST HAS BEEN MADE TO MGGT ARPT FOR A GOV FLT CHK TO VALIDATE THE ILS EQUIP IS OPERATING WITHIN SPECS. UNTIL THAT RPT IS RECEIVED, THE ACR HAS IMPLEMENTED ADDITIONAL WX RESTRS FOR FLT OPS.
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.