B737-300 crew had a track deviation in ord class B airspace.

Attributes
ACN	577472
Time
Date	200303
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ord.airport
State Reference	IL
Altitude	msl single value : 5000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	climbout : intermediate altitude
Route In Use	departure : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	577472
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	non adherence : published procedure non adherence : company policies non adherence : clearance non adherence : far other spatial deviation
Independent Detector	atc equipment other atc equipment : radar other controllera
Resolutory Action	controller : issued new clearance controller : issued alert
Consequence	other
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On climb out from ord, runway 22L, was assigned a heading of 040 degrees and altitude of 7000 ft. PNF read back '040, uh 090' for the heading, and set 090 in the heading window. ATC later asked us our heading and then reassigned us a 040 degree heading. It seems both pilots talked ourselves into accepting the 090 degree heading based on the acceptance of the readback, rather than asking ATC again for the heading assignment when it wasn't clearly understood the first time. It would be best to apply company's altitude setting procedures to headings as well, since that would have probably prevented us flying the wrong heading.

Original NASA ASRS Text

Title: B737-300 CREW HAD A TRACK DEV IN ORD CLASS B AIRSPACE.

Narrative: ON CLBOUT FROM ORD, RWY 22L, WAS ASSIGNED A HDG OF 040 DEGS AND ALT OF 7000 FT. PNF READ BACK '040, UH 090' FOR THE HDG, AND SET 090 IN THE HDG WINDOW. ATC LATER ASKED US OUR HDG AND THEN REASSIGNED US A 040 DEG HDG. IT SEEMS BOTH PLTS TALKED OURSELVES INTO ACCEPTING THE 090 DEG HDG BASED ON THE ACCEPTANCE OF THE READBACK, RATHER THAN ASKING ATC AGAIN FOR THE HDG ASSIGNMENT WHEN IT WASN'T CLRLY UNDERSTOOD THE FIRST TIME. IT WOULD BE BEST TO APPLY COMPANY'S ALT SETTING PROCS TO HDGS AS WELL, SINCE THAT WOULD HAVE PROBABLY PREVENTED US FLYING THE WRONG HDG.

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.