Heading track deviation on IAP ILS approach.

Attributes
ACN	209522
Time
Date	199205
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : hou
State Reference	TX
Altitude	msl bound lower : 2000 msl bound upper : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iah
Operator	general aviation : instructional
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other cruise other descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent : approach
Route In Use	approach : straight in
Flight Plan	IFR
Person 1
Affiliation	Other
Function	instruction : instructor oversight : pic
Qualification	pilot : commercial pilot : instrument pilot : cfi
Experience	flight time last 90 days : 120 flight time total : 1100 flight time type : 250
ASRS Report	209522
Person 2
Affiliation	Other
Function	flight crew : single pilot instruction : trainee
Qualification	pilot : private
Events
Anomaly	conflict : airborne less severe non adherence : clearance non adherence : required legal separation other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course other
Consequence	Other
Miss Distance	horizontal : 12000 vertical : 800
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

The student was flying the airplane. We were established on the localizer (10 DME) for the ILS 12R into houston's william P hobby airport. To allow heavy jets to get in front of us (we were too slow), we received vectors away from the localizer, heading 180 degrees. When we were about 2-3 mi south of the localizer course, all 3 occupants of our airplane heard the following ATC clearance: '...left turn to intercept the localizer 12R.' we were convinced the clearance was for us, and the student read back 'xyz' (last 3 letters of identify north number) as we were heading east to intercept the localizer. We could see an medium large transport on the localizer, about 800 ft above us, and 2 mi to the left (our 10 O'clock position). At the same time ATC ordered an immediate right turn to 180 degrees and asked why we had changed our heading. ATC requested that we contact the ATC supervisor after landing, which I did. I believe this incident could have been prevented easily if we had read back the clearance plus north number ATC could have corrected the misunderstanding before any problems could have arose.

Original NASA ASRS Text

Title: HDG TRACK DEV ON IAP ILS APCH.

Narrative: THE STUDENT WAS FLYING THE AIRPLANE. WE WERE ESTABLISHED ON THE LOC (10 DME) FOR THE ILS 12R INTO HOUSTON'S WILLIAM P HOBBY ARPT. TO ALLOW HVY JETS TO GET IN FRONT OF US (WE WERE TOO SLOW), WE RECEIVED VECTORS AWAY FROM THE LOC, HDG 180 DEGS. WHEN WE WERE ABOUT 2-3 MI S OF THE LOC COURSE, ALL 3 OCCUPANTS OF OUR AIRPLANE HEARD THE FOLLOWING ATC CLRNC: '...L TURN TO INTERCEPT THE LOC 12R.' WE WERE CONVINCED THE CLRNC WAS FOR US, AND THE STUDENT READ BACK 'XYZ' (LAST 3 LETTERS OF IDENT N NUMBER) AS WE WERE HDG E TO INTERCEPT THE LOC. WE COULD SEE AN MLG ON THE LOC, ABOUT 800 FT ABOVE US, AND 2 MI TO THE L (OUR 10 O'CLOCK POS). AT THE SAME TIME ATC ORDERED AN IMMEDIATE R TURN TO 180 DEGS AND ASKED WHY WE HAD CHANGED OUR HDG. ATC REQUESTED THAT WE CONTACT THE ATC SUPVR AFTER LNDG, WHICH I DID. I BELIEVE THIS INCIDENT COULD HAVE BEEN PREVENTED EASILY IF WE HAD READ BACK THE CLRNC PLUS N NUMBER ATC COULD HAVE CORRECTED THE MISUNDERSTANDING BEFORE ANY PROBLEMS COULD HAVE AROSE.

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.