DA50 crew had altitude deviation.

Attributes
ACN	444068
Time
Date	199907
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : gtf.airport
State Reference	MT
Altitude	msl bound lower : 38000 msl bound upper : 39000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc.artcc
Operator	general aviation : corporate
Make Model Name	Falcon 50
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp pilot : multi engine
Experience	flight time last 90 days : 60 flight time total : 4700 flight time type : 700
ASRS Report	444068
Person 2
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was the PNF operating the radios. We checked in with a controller who was working 2 frequencys. When finally able to check in, he replied with our call sign. Then he responded with what I thought was our call sign for a descent to a lower altitude. I responded with our call sign descending to FL290. Descending through the first thousand ft, controller responded by saying we were not authority/authorized for a descent. He then cleared us for a descent. I responded that I did acknowledge the initial clearance. I believe there was no conflict caused. I think what happened was the person who the clearance was for responded on the other frequency the same time we did. With the controller working 2 frequencys, he probably blocked our response out. Also was the fact we were at the point in flight where we were going to ask for descent so it seemed natural to be given it. I think fatigue played a role as I was up at XA00 am and in the office doing paperwork all day. We were supposed to leave at XC00 pm but was delayed until XB00 pm. It felt like a very long day.

Original NASA ASRS Text

Title: DA50 CREW HAD ALTDEV.

Narrative: I WAS THE PNF OPERATING THE RADIOS. WE CHKED IN WITH A CTLR WHO WAS WORKING 2 FREQS. WHEN FINALLY ABLE TO CHK IN, HE REPLIED WITH OUR CALL SIGN. THEN HE RESPONDED WITH WHAT I THOUGHT WAS OUR CALL SIGN FOR A DSCNT TO A LOWER ALT. I RESPONDED WITH OUR CALL SIGN DSNDING TO FL290. DSNDING THROUGH THE FIRST THOUSAND FT, CTLR RESPONDED BY SAYING WE WERE NOT AUTH FOR A DSCNT. HE THEN CLRED US FOR A DSCNT. I RESPONDED THAT I DID ACKNOWLEDGE THE INITIAL CLRNC. I BELIEVE THERE WAS NO CONFLICT CAUSED. I THINK WHAT HAPPENED WAS THE PERSON WHO THE CLRNC WAS FOR RESPONDED ON THE OTHER FREQ THE SAME TIME WE DID. WITH THE CTLR WORKING 2 FREQS, HE PROBABLY BLOCKED OUR RESPONSE OUT. ALSO WAS THE FACT WE WERE AT THE POINT IN FLT WHERE WE WERE GOING TO ASK FOR DSCNT SO IT SEEMED NATURAL TO BE GIVEN IT. I THINK FATIGUE PLAYED A ROLE AS I WAS UP AT XA00 AM AND IN THE OFFICE DOING PAPERWORK ALL DAY. WE WERE SUPPOSED TO LEAVE AT XC00 PM BUT WAS DELAYED UNTIL XB00 PM. IT FELT LIKE A VERY LONG DAY.

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.