C172 pilot and controller miscommunicate a descent clearance.

Attributes
ACN	408880
Time
Date	199807
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : oma
State Reference	NE
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oma
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	descent : approach descent other
Route In Use	arrival other enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 46 flight time total : 456 flight time type : 247
ASRS Report	408880
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	other anomaly other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

I was on an instrument flight plan from sioux city, ia, to omaha, northeast, on victor 159, heading 150 degrees, at 5000 ft approximately 25 mi from omaha. I received a clearance to 'intercept and track the localizer' for the ILS for runway 18. I understood that I was to remain at 5000 ft until intercepting the localizer. Apparently the controller (omaha approach) expected differently. After I had been flying a heading of 150 degrees for more than 10 mins without intercepting the localizer I called and requested a better vector for the intercept. At this point the controller told me that I should have descended to 3000 ft '20 mi earlier.' I intercepted the localizer at about this time and descended at about 1000 FPM until established on the GS. The rest of the approach went without incident. I attribute this miscom to a number of factors. The first was that I was issued a somewhat confusing (to me anyway) set of instructions, I had been expecting normal vectors for the ILS. I was also not given a heading for the intercept. As it turns out a heading of 150 degrees would eventually intercept the extended localizer but I did not know that at the time and was not told. I also believe that processing all the unexpected information had me somewhat 'behind the airplane' and that during this time it is possible that I missed the communication for a descent to 3000 ft. I honestly do not remember that communication having taken place. I plan on doing a couple of things differently that should help avoid this sort of thing in the future. I usually copy all ATC instructions/clrncs when I receive them. I did not do this this time partly because of the increased workload (I was IMC at the time). This is especially important during these times and this is a good lesson learned. I also have been dedicating my IFR practice time to primarily local approachs. I now plan on including short xcountries to other airports in order to get more experience in the IFR system.

Original NASA ASRS Text

Title: C172 PLT AND CTLR MISCOMMUNICATE A DSCNT CLRNC.

Narrative: I WAS ON AN INST FLT PLAN FROM SIOUX CITY, IA, TO OMAHA, NE, ON VICTOR 159, HDG 150 DEGS, AT 5000 FT APPROX 25 MI FROM OMAHA. I RECEIVED A CLRNC TO 'INTERCEPT AND TRACK THE LOC' FOR THE ILS FOR RWY 18. I UNDERSTOOD THAT I WAS TO REMAIN AT 5000 FT UNTIL INTERCEPTING THE LOC. APPARENTLY THE CTLR (OMAHA APCH) EXPECTED DIFFERENTLY. AFTER I HAD BEEN FLYING A HDG OF 150 DEGS FOR MORE THAN 10 MINS WITHOUT INTERCEPTING THE LOC I CALLED AND REQUESTED A BETTER VECTOR FOR THE INTERCEPT. AT THIS POINT THE CTLR TOLD ME THAT I SHOULD HAVE DSNDED TO 3000 FT '20 MI EARLIER.' I INTERCEPTED THE LOC AT ABOUT THIS TIME AND DSNDED AT ABOUT 1000 FPM UNTIL ESTABLISHED ON THE GS. THE REST OF THE APCH WENT WITHOUT INCIDENT. I ATTRIBUTE THIS MISCOM TO A NUMBER OF FACTORS. THE FIRST WAS THAT I WAS ISSUED A SOMEWHAT CONFUSING (TO ME ANYWAY) SET OF INSTRUCTIONS, I HAD BEEN EXPECTING NORMAL VECTORS FOR THE ILS. I WAS ALSO NOT GIVEN A HEADING FOR THE INTERCEPT. AS IT TURNS OUT A HDG OF 150 DEGS WOULD EVENTUALLY INTERCEPT THE EXTENDED LOC BUT I DID NOT KNOW THAT AT THE TIME AND WAS NOT TOLD. I ALSO BELIEVE THAT PROCESSING ALL THE UNEXPECTED INFO HAD ME SOMEWHAT 'BEHIND THE AIRPLANE' AND THAT DURING THIS TIME IT IS POSSIBLE THAT I MISSED THE COM FOR A DSCNT TO 3000 FT. I HONESTLY DO NOT REMEMBER THAT COM HAVING TAKEN PLACE. I PLAN ON DOING A COUPLE OF THINGS DIFFERENTLY THAT SHOULD HELP AVOID THIS SORT OF THING IN THE FUTURE. I USUALLY COPY ALL ATC INSTRUCTIONS/CLRNCS WHEN I RECEIVE THEM. I DID NOT DO THIS THIS TIME PARTLY BECAUSE OF THE INCREASED WORKLOAD (I WAS IMC AT THE TIME). THIS IS ESPECIALLY IMPORTANT DURING THESE TIMES AND THIS IS A GOOD LESSON LEARNED. I ALSO HAVE BEEN DEDICATING MY IFR PRACTICE TIME TO PRIMARILY LCL APCHS. I NOW PLAN ON INCLUDING SHORT XCOUNTRIES TO OTHER ARPTS IN ORDER TO GET MORE EXPERIENCE IN THE IFR 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.