 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
A B727-200 follows a false GS induced by a parked B747 too near the approach end of runway 17C at dfw, tx.
| Attributes | |
| ACN | 473903 |
| Time | |
| Date | 200005 |
| Day | Wed |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : dfw.airport |
| State Reference | TX |
| Altitude | msl single value : 4000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tower : dfw.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B727-200 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | ils localizer & glide slope : 17c |
| Flight Phase | descent : approach |
| Route In Use | approach : straight in approach : instrument precision |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | tower : dfw.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B747 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : holding |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 473903 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : multi engine pilot : commercial |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : overshoot altitude deviation : crossing restriction not met non adherence : published procedure non adherence : clearance other anomaly other anomaly other other spatial deviation |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : overrode automation flight crew : became reoriented flight crew : returned to original clearance |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Problem Areas | Navigational Facility Aircraft Airport ATC Human Performance Flight Crew Human Performance |
| Primary Problem | Navigational Facility |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Intercepted 20 NM final runway 17C dfw. At 4000 ft and 12 NM out we captured false GS. First officer flying and descended well below glide path. Corrected by VASI and normal landing. Conditions were VFR and noticed B747 holding short on east side of runway 17C. Possible disruption of GS signal. I believe no aircraft should hold short so close to the antenna. Could have been hazardous IFR even if unprotected at 800 ft and 2 mi visibility. ATC had no idea of the possible hazard and did not notify approaching aircraft until the complaints started. Callback conversation with reporter revealed the following information: captain stated that the problem with the GS was discovered when the crew noted the altitude deviation via the VASI lights on runway 17C. They didn't have time, due to frequency congestion, to complain to the tower until after they were on the ground and other flts began complaining. They called in and agreed with the comments on frequency. The B747 was right up to the runway hold short line. Reporter believes that 800 ft and 2 mi are the limits where ATC starts protecting the ILS GS transmitter by having aircraft hold further back.
Original NASA ASRS Text
Title: A B727-200 FOLLOWS A FALSE GS INDUCED BY A PARKED B747 TOO NEAR THE APCH END OF RWY 17C AT DFW, TX.
Narrative: INTERCEPTED 20 NM FINAL RWY 17C DFW. AT 4000 FT AND 12 NM OUT WE CAPTURED FALSE GS. FO FLYING AND DSNDED WELL BELOW GLIDE PATH. CORRECTED BY VASI AND NORMAL LNDG. CONDITIONS WERE VFR AND NOTICED B747 HOLDING SHORT ON E SIDE OF RWY 17C. POSSIBLE DISRUPTION OF GS SIGNAL. I BELIEVE NO ACFT SHOULD HOLD SHORT SO CLOSE TO THE ANTENNA. COULD HAVE BEEN HAZARDOUS IFR EVEN IF UNPROTECTED AT 800 FT AND 2 MI VISIBILITY. ATC HAD NO IDEA OF THE POSSIBLE HAZARD AND DID NOT NOTIFY APCHING ACFT UNTIL THE COMPLAINTS STARTED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CAPT STATED THAT THE PROB WITH THE GS WAS DISCOVERED WHEN THE CREW NOTED THE ALTDEV VIA THE VASI LIGHTS ON RWY 17C. THEY DIDN'T HAVE TIME, DUE TO FREQ CONGESTION, TO COMPLAIN TO THE TWR UNTIL AFTER THEY WERE ON THE GND AND OTHER FLTS BEGAN COMPLAINING. THEY CALLED IN AND AGREED WITH THE COMMENTS ON FREQ. THE B747 WAS RIGHT UP TO THE RWY HOLD SHORT LINE. RPTR BELIEVES THAT 800 FT AND 2 MI ARE THE LIMITS WHERE ATC STARTS PROTECTING THE ILS GS XMITTER BY HAVING ACFT HOLD FURTHER BACK.
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.