Flight crew misunderstood altitude clearance during descent. Resulting in loss of separation. Contro...

Attributes
ACN	308470
Time
Date	199506
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : scy
State Reference	TX
Altitude	msl bound lower : 6000 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw
Operator	common carrier : air taxi
Make Model Name	Gates Learjet Corp Undifferentiated or Other Model
Operating Under FAR Part	Part 135
Flight Phase	cruise other descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	ATR Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other descent other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : first officer
Qualification	pilot : instrument pilot : cfi pilot : commercial
Experience	flight time last 90 days : 120 flight time total : 3000 flight time type : 40
ASRS Report	308470
Person 2
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other other
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 800
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were cleared to cross beckx intersection at 7000 ft. Beckx intersection is 7 mi north of the scurry VOR on the 313 degree radial. I thought we were cleared to 7000 ft and the PNF read back cross beckx at 7000 ft, cleared to 6000 ft. He put 6000 ft in the altitude alerter. A regional carrier ATR was below us en route to scurry as well. I heard him cleared to 6000 ft as well. ZFW called the traffic to us and we saw him. He was 5 mi in front of us and several thousand ft lower. We were told to maintain visual separation. We read back that we would maintain visual separation. I failed to hear what the PNF read back to ZFW about the altitude clearance. At 8000 ft I called out '8000 ft for 7000 ft.' the PNF said 'yes, but we are cleared to 6000 ft.' I confirmed this by looking at the altitude alerter and 6000 ft was in there. I figured that I had gotten confused with what we were cleared to with that of the ATR. At 6200 ft several mi south of beckx, center said 'lear XXX, say altitude.' the PNF read back 'XXX level 6000 ft.' center came back to say we were cleared to 7000 ft and did we still have the ATR in sight. We did and we were cleared back to 7000 ft. Center said no problem because we had the regional carrier aircraft in sight. The regional carrier ATR had a TCASII RA and he stayed above us. The problem lies with the fact that we had both been up since early am and we were on our 7TH leg of the day. We had been down to mexico and had a full days work. I had only 2 hours sleep and the PNF had 3 hours sleep the night before. I feel that if the 135 regulations on duty time are rewritten to account for the time of day a pilot starts duty time and adjust the maximum he/she can be on duty that flying would be safer for all of us. We were well within our duty time but we started at early am in the morning. When people get tired people make mistakes. There are too many loop holes in the 135 duty regulations. The FAA should make our regulations more like 121 regulations.

Original NASA ASRS Text

Title: FLC MISUNDERSTOOD ALT CLRNC DURING DSCNT. RESULTING IN LOSS OF SEPARATION. CTLR INTERVENED.

Narrative: WE WERE CLRED TO CROSS BECKX INTXN AT 7000 FT. BECKX INTXN IS 7 MI N OF THE SCURRY VOR ON THE 313 DEG RADIAL. I THOUGHT WE WERE CLRED TO 7000 FT AND THE PNF READ BACK CROSS BECKX AT 7000 FT, CLRED TO 6000 FT. HE PUT 6000 FT IN THE ALT ALERTER. A REGIONAL CARRIER ATR WAS BELOW US ENRTE TO SCURRY AS WELL. I HEARD HIM CLRED TO 6000 FT AS WELL. ZFW CALLED THE TFC TO US AND WE SAW HIM. HE WAS 5 MI IN FRONT OF US AND SEVERAL THOUSAND FT LOWER. WE WERE TOLD TO MAINTAIN VISUAL SEPARATION. WE READ BACK THAT WE WOULD MAINTAIN VISUAL SEPARATION. I FAILED TO HEAR WHAT THE PNF READ BACK TO ZFW ABOUT THE ALT CLRNC. AT 8000 FT I CALLED OUT '8000 FT FOR 7000 FT.' THE PNF SAID 'YES, BUT WE ARE CLRED TO 6000 FT.' I CONFIRMED THIS BY LOOKING AT THE ALT ALERTER AND 6000 FT WAS IN THERE. I FIGURED THAT I HAD GOTTEN CONFUSED WITH WHAT WE WERE CLRED TO WITH THAT OF THE ATR. AT 6200 FT SEVERAL MI S OF BECKX, CTR SAID 'LEAR XXX, SAY ALT.' THE PNF READ BACK 'XXX LEVEL 6000 FT.' CTR CAME BACK TO SAY WE WERE CLRED TO 7000 FT AND DID WE STILL HAVE THE ATR IN SIGHT. WE DID AND WE WERE CLRED BACK TO 7000 FT. CTR SAID NO PROB BECAUSE WE HAD THE REGIONAL CARRIER ACFT IN SIGHT. THE REGIONAL CARRIER ATR HAD A TCASII RA AND HE STAYED ABOVE US. THE PROB LIES WITH THE FACT THAT WE HAD BOTH BEEN UP SINCE EARLY AM AND WE WERE ON OUR 7TH LEG OF THE DAY. WE HAD BEEN DOWN TO MEXICO AND HAD A FULL DAYS WORK. I HAD ONLY 2 HRS SLEEP AND THE PNF HAD 3 HRS SLEEP THE NIGHT BEFORE. I FEEL THAT IF THE 135 REGS ON DUTY TIME ARE REWRITTEN TO ACCOUNT FOR THE TIME OF DAY A PLT STARTS DUTY TIME AND ADJUST THE MAX HE/SHE CAN BE ON DUTY THAT FLYING WOULD BE SAFER FOR ALL OF US. WE WERE WELL WITHIN OUR DUTY TIME BUT WE STARTED AT EARLY AM IN THE MORNING. WHEN PEOPLE GET TIRED PEOPLE MAKE MISTAKES. THERE ARE TOO MANY LOOP HOLES IN THE 135 DUTY REGS. THE FAA SHOULD MAKE OUR REGS MORE LIKE 121 REGS.

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.

Flight crew misunderstood altitude clearance during descent. Resulting in loss of separation. Controller intervened.