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Flight crew of a B737-300 has off red flags on the localizer HSI indicators 15 mi out and believes that it was frequency interference since ATC advised that the airport transmitter was showing green.
| Attributes | |
| ACN | 427575 |
| Time | |
| Date | 199902 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : iah |
| State Reference | TX |
| Altitude | msl bound lower : 2000 msl bound upper : 3000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : commercial pilot : cfi pilot : instrument pilot : flight engineer |
| Experience | flight time last 90 days : 220 flight time total : 17000 flight time type : 3000 |
| ASRS Report | 427575 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial |
| Events | |
| Anomaly | aircraft equipment problem : less severe other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | aircraft : equipment problem dissipated |
| Consequence | Other |
| Supplementary | |
| Air Traffic Incident | other |
Narrative:
First officer flying. On downwind to ILS to runway 27 at iah, approach check was completed 'down to line.' this included identify of ILS frequency. On 290 degree heading to intercept localizer to runway 27 (265 degrees), both HSI's went to an 'off' (flag) indication on the localizer portion. VOR/localizer was selected. I asked the tower to verify operational status of the ILS while I checked the aural indication again -- the aural indication was good. Tower said they showed the signal to be 'green' (good). We attempted to select LNAV, but it would not engage. We were then told we had flown through the localizer and to turn left. After a couple of resettings of the frequency and ATC headings, we went around and got headings for a runway 26 ILS. On 'approach' engagement for the ILS runway 26 the same thing happened. We selected heading, then re-engaged approach and the flags disappeared. The rest of the approach was normal to runway 26.
Original NASA ASRS Text
Title: FLC OF A B737-300 HAS OFF RED FLAGS ON THE LOC HSI INDICATORS 15 MI OUT AND BELIEVES THAT IT WAS FREQ INTERFERENCE SINCE ATC ADVISED THAT THE ARPT XMITTER WAS SHOWING GREEN.
Narrative: FO FLYING. ON DOWNWIND TO ILS TO RWY 27 AT IAH, APCH CHK WAS COMPLETED 'DOWN TO LINE.' THIS INCLUDED IDENT OF ILS FREQ. ON 290 DEG HDG TO INTERCEPT LOC TO RWY 27 (265 DEGS), BOTH HSI'S WENT TO AN 'OFF' (FLAG) INDICATION ON THE LOC PORTION. VOR/LOC WAS SELECTED. I ASKED THE TWR TO VERIFY OPERATIONAL STATUS OF THE ILS WHILE I CHKED THE AURAL INDICATION AGAIN -- THE AURAL INDICATION WAS GOOD. TWR SAID THEY SHOWED THE SIGNAL TO BE 'GREEN' (GOOD). WE ATTEMPTED TO SELECT LNAV, BUT IT WOULD NOT ENGAGE. WE WERE THEN TOLD WE HAD FLOWN THROUGH THE LOC AND TO TURN L. AFTER A COUPLE OF RESETTINGS OF THE FREQ AND ATC HDGS, WE WENT AROUND AND GOT HDGS FOR A RWY 26 ILS. ON 'APCH' ENGAGEMENT FOR THE ILS RWY 26 THE SAME THING HAPPENED. WE SELECTED HDG, THEN RE-ENGAGED APCH AND THE FLAGS DISAPPEARED. THE REST OF THE APCH WAS NORMAL TO RWY 26.
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.