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Less than standard separation with another aircraft while on glide slope localizer. Operational error.
| Attributes | |
| ACN | 115432 |
| Time | |
| Date | 198906 |
| Day | Thu |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : iah |
| State Reference | TX |
| Altitude | msl bound lower : 1900 msl bound upper : 3000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tower : iah |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | descent : approach descent other |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | climbout : intermediate altitude |
| Route In Use | departure sid : sid |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : instrument pilot : commercial |
| Experience | flight time last 90 days : 210 flight time total : 15500 flight time type : 10500 |
| ASRS Report | 115432 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : commercial pilot : flight engineer pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 12000 flight time type : 5000 |
| ASRS Report | 115248 |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation other anomaly other |
| Independent Detector | other controllera |
| Resolutory Action | none taken : anomaly accepted |
| Consequence | faa : reviewed incident with flight crew |
| Miss Distance | horizontal : 12000 vertical : 500 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error Inter Facility Coordination Failure other |
| Situations | |
| ATC Facility | procedure or policy : unspecified |
Narrative:
After crossing nixin the local controller asked us to increase our rate of descent and that we had traffic 500' above us at 12 O'clock and 2 mi. The first officer responded that we were unable to comply as we were on the ILS on the glide slope. Local controller then replied that traffic was no longer a factor. After parking at the gate I called the tower supervisor. He was very defensive and insinuated that we were high (2300'). We were not. I believe local turned a runway 14 departure too early and caused the conflict. Supplemental information from acn 115248: after intercepting localizer we also intercepted glide slope. Our rate of descent was approximately 500 FPM down to 200' which is mandatory glide slope intercept altitude for this ILS 26. After passing nixin LOM on glide slope we were instructed by iah tower to increase our rate of descent that we had traffic at 12 O'clock position. I replied that we were on the glide slope and that we could not descend. At this point I told the captain that I could ont believe he just asked us to descend when we were inside the LOM and on glide slope. Contributing factors: departing aircraft flying the intercontinental four departure SID are turned left off of runway 14 for east and northeast departures and cleared only to 4000'. I believe approach control brought us too close to nixin LOM at 3000' and our normal rate of descent brought us down to the mandatory 2000' altitude just prior to nixin.
Original NASA ASRS Text
Title: LESS THAN STANDARD SEPARATION WITH ANOTHER ACFT WHILE ON GLIDE SLOPE LOCALIZER. OPERATIONAL ERROR.
Narrative: AFTER XING NIXIN THE LCL CTLR ASKED US TO INCREASE OUR RATE OF DSCNT AND THAT WE HAD TFC 500' ABOVE US AT 12 O'CLOCK AND 2 MI. THE F/O RESPONDED THAT WE WERE UNABLE TO COMPLY AS WE WERE ON THE ILS ON THE GLIDE SLOPE. LCL CTLR THEN REPLIED THAT TFC WAS NO LONGER A FACTOR. AFTER PARKING AT THE GATE I CALLED THE TWR SUPVR. HE WAS VERY DEFENSIVE AND INSINUATED THAT WE WERE HIGH (2300'). WE WERE NOT. I BELIEVE LCL TURNED A RWY 14 DEP TOO EARLY AND CAUSED THE CONFLICT. SUPPLEMENTAL INFORMATION FROM ACN 115248: AFTER INTERCEPTING LOC WE ALSO INTERCEPTED GLIDE SLOPE. OUR RATE OF DSCNT WAS APPROX 500 FPM DOWN TO 200' WHICH IS MANDATORY GLIDE SLOPE INTERCEPT ALT FOR THIS ILS 26. AFTER PASSING NIXIN LOM ON GLIDE SLOPE WE WERE INSTRUCTED BY IAH TWR TO INCREASE OUR RATE OF DSCNT THAT WE HAD TFC AT 12 O'CLOCK POSITION. I REPLIED THAT WE WERE ON THE GLIDE SLOPE AND THAT WE COULD NOT DSND. AT THIS POINT I TOLD THE CAPT THAT I COULD ONT BELIEVE HE JUST ASKED US TO DSND WHEN WE WERE INSIDE THE LOM AND ON GLIDE SLOPE. CONTRIBUTING FACTORS: DEPARTING ACFT FLYING THE INTERCONTINENTAL FOUR DEP SID ARE TURNED LEFT OFF OF RWY 14 FOR EAST AND NE DEPS AND CLRED ONLY TO 4000'. I BELIEVE APCH CTL BROUGHT US TOO CLOSE TO NIXIN LOM AT 3000' AND OUR NORMAL RATE OF DSCNT BROUGHT US DOWN TO THE MANDATORY 2000' ALT JUST PRIOR TO NIXIN.
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.