Small aircraft was cleared climb to 5000', thought 6000' and got to 5600'.

Attributes
ACN	174736
Time
Date	199103
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : sbj airport : mmu
State Reference	NJ
Altitude	msl bound lower : 5000 msl bound upper : 5600
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : n90
Operator	general aviation : instructional
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 90 flight time total : 720 flight time type : 680
ASRS Report	174736
Person 2
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
Events
Anomaly	altitude deviation : overshoot non adherence : clearance non adherence other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Was IFR from mmo using mmu 3 departure. I was then given to ny approach. After some time, I was given 6000'. I repeated back, 'out of 4000 for 6000.' some time later (about 1 min) I was ordered, 'expedite through 5000.' I replied, 'expedite through 5000.' at 5600', ny approach questioned altitude. I replied, 'at 5600 for 6000.' ny approach repeated 3 times that I had only been cleared to 5000', but now that I was up there, should maintain 6000'. Controller seemed to be upset. I reached 6000' and leveled about 40 seconds later (roc about 600 FPM). 6000' was the flight plan altitude, was the expect after 5 mins altitude in the clearance, and was the appropriate altitude for the direction of flight (about 245 degrees). It is possible that the controller gave me 5000', but 6000' was repeated back west/O query by the controller. I believe the controller called for 6000' but remembered 5000'. His order to expedite through 5000' is not easily explained if he believed he had ordered me to 5000'. On the other hand, if he attempted to change the altitude order by saying, 'expedite to 5000,' this was not heard as a new clearance, it was understood as, 'expedite through 5000.' I was IMC between 2 layers. Visibility was about 10 mi. There was no nearby (less than 5 mi) traffic.

Original NASA ASRS Text

Title: SMA WAS CLEARED CLIMB TO 5000', THOUGHT 6000' AND GOT TO 5600'.

Narrative: WAS IFR FROM MMO USING MMU 3 DEP. I WAS THEN GIVEN TO NY APCH. AFTER SOME TIME, I WAS GIVEN 6000'. I REPEATED BACK, 'OUT OF 4000 FOR 6000.' SOME TIME LATER (ABOUT 1 MIN) I WAS ORDERED, 'EXPEDITE THROUGH 5000.' I REPLIED, 'EXPEDITE THROUGH 5000.' AT 5600', NY APCH QUESTIONED ALT. I REPLIED, 'AT 5600 FOR 6000.' NY APCH REPEATED 3 TIMES THAT I HAD ONLY BEEN CLRED TO 5000', BUT NOW THAT I WAS UP THERE, SHOULD MAINTAIN 6000'. CTLR SEEMED TO BE UPSET. I REACHED 6000' AND LEVELED ABOUT 40 SECS LATER (ROC ABOUT 600 FPM). 6000' WAS THE FLT PLAN ALT, WAS THE EXPECT AFTER 5 MINS ALT IN THE CLRNC, AND WAS THE APPROPRIATE ALT FOR THE DIRECTION OF FLT (ABOUT 245 DEGS). IT IS POSSIBLE THAT THE CTLR GAVE ME 5000', BUT 6000' WAS REPEATED BACK W/O QUERY BY THE CTLR. I BELIEVE THE CTLR CALLED FOR 6000' BUT REMEMBERED 5000'. HIS ORDER TO EXPEDITE THROUGH 5000' IS NOT EASILY EXPLAINED IF HE BELIEVED HE HAD ORDERED ME TO 5000'. ON THE OTHER HAND, IF HE ATTEMPTED TO CHANGE THE ALT ORDER BY SAYING, 'EXPEDITE TO 5000,' THIS WAS NOT HEARD AS A NEW CLRNC, IT WAS UNDERSTOOD AS, 'EXPEDITE THROUGH 5000.' I WAS IMC BTWN 2 LAYERS. VISIBILITY WAS ABOUT 10 MI. THERE WAS NO NEARBY (LESS THAN 5 MI) TFC.

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.