Flight crew of CL60 mishear cleared altitude and climb through cleared altitude.

Attributes
ACN	601462
Time
Date	200311
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : pbi.airport
State Reference	FL
Altitude	msl single value : 13000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pbi.tracon
Operator	general aviation : corporate
Make Model Name	Challenger CL601
Operating Under FAR Part	Part 91
Flight Phase	climbout : initial climbout : intermediate altitude
Route In Use	departure : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 150 flight time total : 12000
ASRS Report	601462
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	altitude deviation : overshoot non adherence : company policies non adherence : far non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued alert flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance ATC Facility Aircraft Company Environmental Factor
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On the last of 4 legs we departed west palm beach (pbi) en route washington (iad). The aircraft was passed from pbi tower to departure control. When communications was established with pbi departure all xmissions from departure control were very weak and numerous readbacks were required. I was assigned what I thought was 13000 ft and set the altitude alert for that altitude. As the aircraft was passing through 12800 ft we were informed by departure that our assigned altitude was 12000 ft. The sic, who was flying the aircraft, immediately descended to 12000 ft. As the descent to 12000 ft was initiated I told the controller that I thought we were assigned 13000 ft and she said no it was 12000 ft. I do not remember the altitude that I read back to her but I assume since I set 13000 ft in the altitude alert that is what I read back. In my opinion some contributing things here are: 1) the signal from departure control was very weak. I told them we were receiving them weak at our initial contact. 2) normal procedures are to use headset and boom microphone below 10000 ft but we were using the aircraft speaker since one headset was inoperative. 3) the full departure was not entered into the FMS. 4) the old company policy was that headsets were supplied by the company and remained in the aircraft. The new policy is each crew member provides his/her own headset and they carry it with them when they leave the aircraft. Not all crew members have purchased a headset and there is no standard type specified to purchase so not all headset microphone levels are the same for the intercom system.

Original NASA ASRS Text

Title: FLT CREW OF CL60 MISHEAR CLRED ALT AND CLB THROUGH CLRED ALT.

Narrative: ON THE LAST OF 4 LEGS WE DEPARTED WEST PALM BEACH (PBI) ENRTE WASHINGTON (IAD). THE ACFT WAS PASSED FROM PBI TWR TO DEP CTL. WHEN COMS WAS ESTABLISHED WITH PBI DEP ALL XMISSIONS FROM DEP CTL WERE VERY WEAK AND NUMEROUS READBACKS WERE REQUIRED. I WAS ASSIGNED WHAT I THOUGHT WAS 13000 FT AND SET THE ALT ALERT FOR THAT ALT. AS THE ACFT WAS PASSING THROUGH 12800 FT WE WERE INFORMED BY DEP THAT OUR ASSIGNED ALT WAS 12000 FT. THE SIC, WHO WAS FLYING THE ACFT, IMMEDIATELY DSNDED TO 12000 FT. AS THE DSCNT TO 12000 FT WAS INITIATED I TOLD THE CTLR THAT I THOUGHT WE WERE ASSIGNED 13000 FT AND SHE SAID NO IT WAS 12000 FT. I DO NOT REMEMBER THE ALT THAT I READ BACK TO HER BUT I ASSUME SINCE I SET 13000 FT IN THE ALT ALERT THAT IS WHAT I READ BACK. IN MY OPINION SOME CONTRIBUTING THINGS HERE ARE: 1) THE SIGNAL FROM DEP CTL WAS VERY WEAK. I TOLD THEM WE WERE RECEIVING THEM WEAK AT OUR INITIAL CONTACT. 2) NORMAL PROCS ARE TO USE HEADSET AND BOOM MIKE BELOW 10000 FT BUT WE WERE USING THE ACFT SPEAKER SINCE ONE HEADSET WAS INOP. 3) THE FULL DEP WAS NOT ENTERED INTO THE FMS. 4) THE OLD COMPANY POLICY WAS THAT HEADSETS WERE SUPPLIED BY THE COMPANY AND REMAINED IN THE ACFT. THE NEW POLICY IS EACH CREW MEMBER PROVIDES HIS/HER OWN HEADSET AND THEY CARRY IT WITH THEM WHEN THEY LEAVE THE ACFT. NOT ALL CREW MEMBERS HAVE PURCHASED A HEADSET AND THERE IS NO STANDARD TYPE SPECIFIED TO PURCHASE SO NOT ALL HEADSET MIKE LEVELS ARE THE SAME FOR THE INTERCOM 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.