Charter small transport track heading deviation during radar vectors into pdk.

Attributes
ACN	160465
Time
Date	199010
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : pdk
State Reference	GA
Altitude	msl bound lower : 14000 msl bound upper : 18000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	general aviation : instructional
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other descent other
Route In Use	enroute : direct enroute : on vectors enroute other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 90 flight time total : 2300 flight time type : 700
ASRS Report	160465
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flying the awson 7 arrival between hours and awson intersection descent was given from 18000 to 14000' and a turn approximately 50 degrees left of arrival route for sep by controller, previous to ZTL 90 degree turn to right heading 260 degrees to join 024 degree right to atl. Told atl ATC assigned 260 degree heading after changeover occurred. A descent to cross tegre at 8000' was then given with direct tegre given as well. Unknown how far ATC had flown us off arrival route. Punched up RNAV direct tegre. Started to what we thought was tegre according to RNAV readout. Approximately 2 mins later ATC asked us what radial off atl we were flying. We replied clear direct tegre to standby for radial. Radial was read out as 95 degrees. ATC said we were approximately 10 mi left of arrival and were now cleared direct pdk. ATC indicated we were not flying toward tegre. Punched up RNAV input data and verified it was correct. Punched up system toward tegre again to check system. It now indicated tegre at close to 90 degrees right of present position. Both pilots were baffled. Problems and explanations: 1) had controller forgotten that we had been flown off the arrival to begin with, cleared us, then looked up seeing aircraft off arrival route and reacted? Had the RNAV system given us erroneous indications? To prevent this problem in future, I will insist copilot back up navigation on his side and rely less heavily on 1 system.

Original NASA ASRS Text

Title: CHARTER SMT TRACK HEADING DEVIATION DURING RADAR VECTORS INTO PDK.

Narrative: FLYING THE AWSON 7 ARR BTWN HRS AND AWSON INTXN DSNT WAS GIVEN FROM 18000 TO 14000' AND A TURN APPROX 50 DEGS LEFT OF ARR RTE FOR SEP BY CTLR, PREVIOUS TO ZTL 90 DEG TURN TO RIGHT HDG 260 DEGS TO JOIN 024 DEG R TO ATL. TOLD ATL ATC ASSIGNED 260 DEG HDG AFTER CHANGEOVER OCCURRED. A DSNT TO CROSS TEGRE AT 8000' WAS THEN GIVEN WITH DIRECT TEGRE GIVEN AS WELL. UNKNOWN HOW FAR ATC HAD FLOWN US OFF ARR RTE. PUNCHED UP RNAV DIRECT TEGRE. STARTED TO WHAT WE THOUGHT WAS TEGRE ACCORDING TO RNAV READOUT. APPROX 2 MINS LATER ATC ASKED US WHAT RADIAL OFF ATL WE WERE FLYING. WE REPLIED CLEAR DIRECT TEGRE TO STANDBY FOR RADIAL. RADIAL WAS READ OUT AS 95 DEGS. ATC SAID WE WERE APPROX 10 MI LEFT OF ARR AND WERE NOW CLRED DIRECT PDK. ATC INDICATED WE WERE NOT FLYING TOWARD TEGRE. PUNCHED UP RNAV INPUT DATA AND VERIFIED IT WAS CORRECT. PUNCHED UP SYS TOWARD TEGRE AGAIN TO CHK SYS. IT NOW INDICATED TEGRE AT CLOSE TO 90 DEGS RIGHT OF PRESENT POS. BOTH PLTS WERE BAFFLED. PROBS AND EXPLANATIONS: 1) HAD CTLR FORGOTTEN THAT WE HAD BEEN FLOWN OFF THE ARR TO BEGIN WITH, CLRED US, THEN LOOKED UP SEEING ACFT OFF ARR RTE AND REACTED? HAD THE RNAV SYS GIVEN US ERRONEOUS INDICATIONS? TO PREVENT THIS PROB IN FUTURE, I WILL INSIST COPLT BACK UP NAV ON HIS SIDE AND RELY LESS HEAVILY ON 1 SYS.

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.