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B727 receives a GPWS and performs an altitude deviation altitude excursion during its evasive action climb. Approach controller said later that this happens 10% of the time in that area.
| Attributes | |
| ACN | 362162 |
| Time | |
| Date | 199702 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : slc |
| State Reference | UT |
| Altitude | msl bound lower : 9000 msl bound upper : 9600 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : slc |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 3 Turbojet Eng |
| Flight Phase | descent : approach |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | cruise other |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 220 flight time total : 9000 flight time type : 7500 |
| ASRS Report | 362162 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter other non adherence : clearance other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : exited adverse environment flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Air Traffic Incident | Pilot Deviation other |
| Situations | |
| ATC Facility | procedure or policy : unspecified |
Narrative:
Flight xyz, en route from geg to slc on feb/fri/97, was being vectored by slc approach control for an ILS approach to runway 34L. At 29 DME iuuh (approximately 2 1/2-3 mi west of the slc runway 34L localizer) from a heading of 155 degrees and at 9000 ft MSL, slc approach issued a left turn to 360 degrees, told us to maintain 9000 ft MSL until established on the localizer and cleared us for the ILS runway 34L approach. As we turned left towards the 360 degree intercept heading (passing through 060 degree heading and IMC) a 'pull up' GPWS warning sounded. The captain initiated a pull up (the radio altimeter indicated terrain at 1000- 1100 ft) and upon climbing through 9500 ft MSL, the radio altimeter began increasing to 2000-2500 ft and the GPWS warning stopped. The first officer advised slc approach of the climb due to terrain avoidance and approach told us to descend to 9000 ft MSL as soon as possible due to traffic above us. We descended from 9600 ft MSL to 9000 ft MSL and were vectored to the runway 34L localizer. The flight continued the approach uneventfully to a landing on runway 34L. It should be noted that at no time during the 'pull up' maneuver did we get any RA's on TCASII and that our altitude deviation did not exceed 600 ft above assigned altitude. After discussing the GPWS 'pull up' event with slc approach, we were advised that the 9000 ft MSL vector altitude is routinely used in that sector and that approximately 1 flight out of 10 flts experiences a GPWS warning in the area where we got our warning. Approach control also confirmed that no traffic conflicts occurred during the 'pull up' maneuver. Since it has been documented by slc approach control that GPWS warnings occur at 9000 ft MSL in this sector, why hasn't this vectoring altitude been raised to a ht where the warnings are eliminated? A warning should also be published in the slc special pages to alert crews of the possibility of a GPWS warning in this sector at 9000 ft MSL. Clearly, the potential for a midair collision exists here when an aircraft has to execute a GPWS terrain pull up and while doing so, climbs into the path of inbound traffic above. Action needs to be taken as soon as possible to fix this problem.
Original NASA ASRS Text
Title: B727 RECEIVES A GPWS AND PERFORMS AN ALTDEV ALT EXCURSION DURING ITS EVASIVE ACTION CLB. APCH CTLR SAID LATER THAT THIS HAPPENS 10% OF THE TIME IN THAT AREA.
Narrative: FLT XYZ, ENRTE FROM GEG TO SLC ON FEB/FRI/97, WAS BEING VECTORED BY SLC APCH CTL FOR AN ILS APCH TO RWY 34L. AT 29 DME IUUH (APPROX 2 1/2-3 MI W OF THE SLC RWY 34L LOC) FROM A HDG OF 155 DEGS AND AT 9000 FT MSL, SLC APCH ISSUED A L TURN TO 360 DEGS, TOLD US TO MAINTAIN 9000 FT MSL UNTIL ESTABLISHED ON THE LOC AND CLRED US FOR THE ILS RWY 34L APCH. AS WE TURNED L TOWARDS THE 360 DEG INTERCEPT HEADING (PASSING THROUGH 060 DEG HDG AND IMC) A 'PULL UP' GPWS WARNING SOUNDED. THE CAPT INITIATED A PULL UP (THE RADIO ALTIMETER INDICATED TERRAIN AT 1000- 1100 FT) AND UPON CLBING THROUGH 9500 FT MSL, THE RADIO ALTIMETER BEGAN INCREASING TO 2000-2500 FT AND THE GPWS WARNING STOPPED. THE FO ADVISED SLC APCH OF THE CLB DUE TO TERRAIN AVOIDANCE AND APCH TOLD US TO DSND TO 9000 FT MSL ASAP DUE TO TFC ABOVE US. WE DSNDED FROM 9600 FT MSL TO 9000 FT MSL AND WERE VECTORED TO THE RWY 34L LOC. THE FLT CONTINUED THE APCH UNEVENTFULLY TO A LNDG ON RWY 34L. IT SHOULD BE NOTED THAT AT NO TIME DURING THE 'PULL UP' MANEUVER DID WE GET ANY RA'S ON TCASII AND THAT OUR ALTDEV DID NOT EXCEED 600 FT ABOVE ASSIGNED ALT. AFTER DISCUSSING THE GPWS 'PULL UP' EVENT WITH SLC APCH, WE WERE ADVISED THAT THE 9000 FT MSL VECTOR ALT IS ROUTINELY USED IN THAT SECTOR AND THAT APPROX 1 FLT OUT OF 10 FLTS EXPERIENCES A GPWS WARNING IN THE AREA WHERE WE GOT OUR WARNING. APCH CTL ALSO CONFIRMED THAT NO TFC CONFLICTS OCCURRED DURING THE 'PULL UP' MANEUVER. SINCE IT HAS BEEN DOCUMENTED BY SLC APCH CTL THAT GPWS WARNINGS OCCUR AT 9000 FT MSL IN THIS SECTOR, WHY HASN'T THIS VECTORING ALT BEEN RAISED TO A HT WHERE THE WARNINGS ARE ELIMINATED? A WARNING SHOULD ALSO BE PUBLISHED IN THE SLC SPECIAL PAGES TO ALERT CREWS OF THE POSSIBILITY OF A GPWS WARNING IN THIS SECTOR AT 9000 FT MSL. CLRLY, THE POTENTIAL FOR A MIDAIR COLLISION EXISTS HERE WHEN AN ACFT HAS TO EXECUTE A GPWS TERRAIN PULL UP AND WHILE DOING SO, CLBS INTO THE PATH OF INBOUND TFC ABOVE. ACTION NEEDS TO BE TAKEN ASAP TO FIX THIS PROB.
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.