GPWS alert. - NASA ASRS

Attributes
ACN	293680
Time
Date	199501
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : avl
State Reference	NC
Altitude	msl bound lower : 6000 msl bound upper : 6500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : avl
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time total : 14000
ASRS Report	293680
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : exited adverse environment flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Flight was on downwind vectors approximately 5 NM of avl. (Heading 360 degrees, altitude 11000 ft, speed 200 KTS.) WX was IFR with multiple layers below 15000 ft. Descent clearance given to maintain 5100 ft. Passing 6000 ft in descent at 800 FPM GPWS alerted with 'terrain, terrain' aural warning. 1 mountain peak was visible but rest of horizon was obscured. Terrain avoidance procedure initiated and aircraft climbed to 6500 ft MSL. ATC was advised of warning and climb, warning ceased passing 6000 ft. The GPWS warning was probably due to computer calculating a flight path below our assigned leveloff altitude. The normal descent profile of this aircraft type will likely trigger more GPWS warnings when being vectored toward the 4064 ft peak northwest of avl resulting in climbs (without clearance) to minimum safe altitude.

Original NASA ASRS Text

Title: GPWS ALERT.

Narrative: FLT WAS ON DOWNWIND VECTORS APPROX 5 NM OF AVL. (HDG 360 DEGS, ALT 11000 FT, SPD 200 KTS.) WX WAS IFR WITH MULTIPLE LAYERS BELOW 15000 FT. DSCNT CLRNC GIVEN TO MAINTAIN 5100 FT. PASSING 6000 FT IN DSCNT AT 800 FPM GPWS ALERTED WITH 'TERRAIN, TERRAIN' AURAL WARNING. 1 MOUNTAIN PEAK WAS VISIBLE BUT REST OF HORIZON WAS OBSCURED. TERRAIN AVOIDANCE PROC INITIATED AND ACFT CLBED TO 6500 FT MSL. ATC WAS ADVISED OF WARNING AND CLB, WARNING CEASED PASSING 6000 FT. THE GPWS WARNING WAS PROBABLY DUE TO COMPUTER CALCULATING A FLT PATH BELOW OUR ASSIGNED LEVELOFF ALT. THE NORMAL DSCNT PROFILE OF THIS ACFT TYPE WILL LIKELY TRIGGER MORE GPWS WARNINGS WHEN BEING VECTORED TOWARD THE 4064 FT PEAK NW OF AVL RESULTING IN CLBS (WITHOUT CLRNC) TO MINIMUM SAFE ALT.

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.