Commuter light transport has heading deviation due to clearance confusion.

Attributes
ACN	295223
Time
Date	199502
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : fwa
State Reference	IN
Altitude	msl bound lower : 16000 msl bound upper : 16000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zau tower : tupj
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 135
Flight Phase	cruise other
Route In Use	enroute : on vectors enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : cfi
Experience	flight time last 90 days : 300 flight time total : 1700 flight time type : 473
ASRS Report	295223
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flying at 16000 ft MSL en route from day to mdw. Upon crossing fwa VOR, received ATC clearance as heading 295 degrees direct cgt direct mdw. Read clearance back to controller as 'left turn to 295 degrees direct chicago heights direct midway.' PF, captain, turned to 295 degrees. Upon receiving cgt, we proceeded direct. He turned an additional 10 degrees left to track inbound to cgt. Approximately 5 mins later, ATC queried whether our heading was 295 degrees. I responded we were proceeding direct cgt. ATC advised our clearance was 295 degrees radar vectors, expect direct cgt direct mdw. Myself and the captain understood the clearance to mean to proceed direct and per my readback, ATC should have clarified. At no point in my readback did I acknowledge an understanding as the 295 degree heading was to be flown until further clearance. Circumstances contributing: 1) third day of a 4-DAY trip with an early morning show time, 12 hour duty, and greater than 7.5 hour flight. 2) controller appeared to be agitated with other aircraft on frequency, possibly tired and nearing the end of shift. 3) ATC clrncs should be clarified both by controller and crew. By not repeating 'expect' in my readback, controller should have restated his intentions.

Original NASA ASRS Text

Title: COMMUTER LTT HAS HDG DEV DUE TO CLRNC CONFUSION.

Narrative: FLYING AT 16000 FT MSL ENRTE FROM DAY TO MDW. UPON XING FWA VOR, RECEIVED ATC CLRNC AS HDG 295 DEGS DIRECT CGT DIRECT MDW. READ CLRNC BACK TO CTLR AS 'L TURN TO 295 DEGS DIRECT CHICAGO HEIGHTS DIRECT MIDWAY.' PF, CAPT, TURNED TO 295 DEGS. UPON RECEIVING CGT, WE PROCEEDED DIRECT. HE TURNED AN ADDITIONAL 10 DEGS L TO TRACK INBOUND TO CGT. APPROX 5 MINS LATER, ATC QUERIED WHETHER OUR HDG WAS 295 DEGS. I RESPONDED WE WERE PROCEEDING DIRECT CGT. ATC ADVISED OUR CLRNC WAS 295 DEGS RADAR VECTORS, EXPECT DIRECT CGT DIRECT MDW. MYSELF AND THE CAPT UNDERSTOOD THE CLRNC TO MEAN TO PROCEED DIRECT AND PER MY READBACK, ATC SHOULD HAVE CLARIFIED. AT NO POINT IN MY READBACK DID I ACKNOWLEDGE AN UNDERSTANDING AS THE 295 DEG HDG WAS TO BE FLOWN UNTIL FURTHER CLRNC. CIRCUMSTANCES CONTRIBUTING: 1) THIRD DAY OF A 4-DAY TRIP WITH AN EARLY MORNING SHOW TIME, 12 HR DUTY, AND GREATER THAN 7.5 HR FLT. 2) CTLR APPEARED TO BE AGITATED WITH OTHER ACFT ON FREQ, POSSIBLY TIRED AND NEARING THE END OF SHIFT. 3) ATC CLRNCS SHOULD BE CLARIFIED BOTH BY CTLR AND CREW. BY NOT REPEATING 'EXPECT' IN MY READBACK, CTLR SHOULD HAVE RESTATED HIS INTENTIONS.

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.