Altitude deviation altitude excursion. Potential conflict less than standard separation.

Attributes
ACN	237913
Time
Date	199303
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : bdf
State Reference	IL
Altitude	msl bound lower : 11000 msl bound upper : 11500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Transport
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute airway : zau
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 90 flight time total : 730 flight time type : 80
ASRS Report	237913
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 27000 vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I filed an IFR flight plan from kankakee, il, to denver, co, at a requested altitude of FL260. I took off VFR and contacted ZAU to pick up my clearance. I was cleared to bdf via V144, which was the beginning of my requested route. I was cleared progressively higher. Shortly after I was cleared to 11000 ft I heard the controller say 'I need you at 11500 ft.' I started an immediate climb, thinking that this was a special situation. At about 11400 ft the controller asked me to say my altitude and stated that I had been cleared to 11000 ft. I then descended to 11000 ft, concluding that I must have misunderstood the controller's request to a VFR pilot in the vicinity. After a few mins the controller contacted me and gave me a phone number to call after landing. I called this number and was told that my climb had resulted in a separation of about 4 1/2 mi. This loss of separation had automatically triggered an alert. I was told that I could expect to be contacted by my local FSDO in about 2 months.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION. POTENTIAL CONFLICT LTSS.

Narrative: I FILED AN IFR FLT PLAN FROM KANKAKEE, IL, TO DENVER, CO, AT A REQUESTED ALT OF FL260. I TOOK OFF VFR AND CONTACTED ZAU TO PICK UP MY CLRNC. I WAS CLRED TO BDF VIA V144, WHICH WAS THE BEGINNING OF MY REQUESTED RTE. I WAS CLRED PROGRESSIVELY HIGHER. SHORTLY AFTER I WAS CLRED TO 11000 FT I HEARD THE CTLR SAY 'I NEED YOU AT 11500 FT.' I STARTED AN IMMEDIATE CLB, THINKING THAT THIS WAS A SPECIAL SIT. AT ABOUT 11400 FT THE CTLR ASKED ME TO SAY MY ALT AND STATED THAT I HAD BEEN CLRED TO 11000 FT. I THEN DSNDED TO 11000 FT, CONCLUDING THAT I MUST HAVE MISUNDERSTOOD THE CTLR'S REQUEST TO A VFR PLT IN THE VICINITY. AFTER A FEW MINS THE CTLR CONTACTED ME AND GAVE ME A PHONE NUMBER TO CALL AFTER LNDG. I CALLED THIS NUMBER AND WAS TOLD THAT MY CLB HAD RESULTED IN A SEPARATION OF ABOUT 4 1/2 MI. THIS LOSS OF SEPARATION HAD AUTOMATICALLY TRIGGERED AN ALERT. I WAS TOLD THAT I COULD EXPECT TO BE CONTACTED BY MY LCL FSDO IN ABOUT 2 MONTHS.

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.