Narrative:

Aug/mon/01, at about XA20, we departed ZZZ1 en route to ZZZ2 on an air ambulance flight. The IFR clearance we received was predicated on a south departure, but the departure runway was changed to runway 36L. I was the PF while the copilot handled the communication. Initial instructions were climb to 2000 ft on runway heading and expect 14000 ft in 10 mins. After contacting departure, we were instructed to turn left to 250 degrees which would put us in close proximity to ZZZ approach course. Anticipating the usual climb clearance to an intermediate altitude, I climbed through 2000 ft and was at 3500 ft when the controller questioned my altitude. After confirming the aircraft altitude, I was instructed to return to 2000 ft. An airliner on approach to runway 19 at ZZZ was held at 3500 ft. After complying with ATC and west of ZZZ, I was instructed to climb and change frequencys. I attribute the incident to anticipating the usual climb instructions to an intermediate altitude without verifying. A contributing factor was the intercom mutes the voice when 1 pilot is transmitting, thereby preventing both pilots from monitoring ATC communications. I had never received an altitude restr this low (2000 ft) prior to this incident and it reinforces the need to confirm clrncs whenever any doubt exists and to beware of assumptions based on past experiences.

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Original NASA ASRS Text

Title: B90 CREW ASSIGNED 2000 FT ON DEP FROM NEW ARPT CLB TO 3000 FT AND INSTRUCTED TO RETURN TO 2000 FT FOR TFC.

Narrative: AUG/MON/01, AT ABOUT XA20, WE DEPARTED ZZZ1 ENRTE TO ZZZ2 ON AN AIR AMBULANCE FLT. THE IFR CLRNC WE RECEIVED WAS PREDICATED ON A S DEP, BUT THE DEP RWY WAS CHANGED TO RWY 36L. I WAS THE PF WHILE THE COPLT HANDLED THE COM. INITIAL INSTRUCTIONS WERE CLB TO 2000 FT ON RWY HEADING AND EXPECT 14000 FT IN 10 MINS. AFTER CONTACTING DEP, WE WERE INSTRUCTED TO TURN L TO 250 DEGS WHICH WOULD PUT US IN CLOSE PROX TO ZZZ APCH COURSE. ANTICIPATING THE USUAL CLB CLRNC TO AN INTERMEDIATE ALT, I CLBED THROUGH 2000 FT AND WAS AT 3500 FT WHEN THE CTLR QUESTIONED MY ALT. AFTER CONFIRMING THE ACFT ALT, I WAS INSTRUCTED TO RETURN TO 2000 FT. AN AIRLINER ON APCH TO RWY 19 AT ZZZ WAS HELD AT 3500 FT. AFTER COMPLYING WITH ATC AND W OF ZZZ, I WAS INSTRUCTED TO CLB AND CHANGE FREQS. I ATTRIBUTE THE INCIDENT TO ANTICIPATING THE USUAL CLB INSTRUCTIONS TO AN INTERMEDIATE ALT WITHOUT VERIFYING. A CONTRIBUTING FACTOR WAS THE INTERCOM MUTES THE VOICE WHEN 1 PLT IS XMITTING, THEREBY PREVENTING BOTH PLTS FROM MONITORING ATC COMS. I HAD NEVER RECEIVED AN ALT RESTR THIS LOW (2000 FT) PRIOR TO THIS INCIDENT AND IT REINFORCES THE NEED TO CONFIRM CLRNCS WHENEVER ANY DOUBT EXISTS AND TO BEWARE OF ASSUMPTIONS BASED ON PAST EXPERIENCES.

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.