Altitude deviation altitude overshot on descent by air carrier medium large transport.

Attributes
ACN	218631
Time
Date	199208
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : fak
State Reference	VA
Altitude	msl bound lower : 19000 msl bound upper : 20000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 170 flight time total : 11950 flight time type : 1093
ASRS Report	218631
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Due to miscom on the part of myself and the controller, we were involved in a descent to an altitude to which we were not cleared. While proceeding toward flat rock (fak) VOR at FL270, we received a clearance to cross fak at 10000 ft. The first officer confirmed that 10000 ft was our cleared altitude. The clearance was received on a frequency of 127.75. I read back the cleared altitude to the controller. We were handed off to the next controller on 132.77. When I checked in I stated that we were descending through FL200 to an assigned altitude of 10000 ft. The controller asked me to repeat our cleared altitude. When I repeated '10000 ft', the controller stated that our cleared altitude was FL200. The lowest altitude reached was FL190, we climbed back up to FL200. No apparent loss of separation took place. Factors affecting the quality of human performance: the first officer was new to the airplane and to our company. I was helping him with programming the FMC system. I should have been suspicious of a clearance to such a low altitude considering the distance from the destination. I also should have questioned a clearance to an 'MSL' altitude without an altimeter setting being given. The controller may have misstated the altitude. If he stated the altitude correctly, he should have heard my incorrect readback.

Original NASA ASRS Text

Title: ALTDEV ALT OVERSHOT ON DSCNT BY ACR MLG.

Narrative: DUE TO MISCOM ON THE PART OF MYSELF AND THE CTLR, WE WERE INVOLVED IN A DSCNT TO AN ALT TO WHICH WE WERE NOT CLRED. WHILE PROCEEDING TOWARD FLAT ROCK (FAK) VOR AT FL270, WE RECEIVED A CLRNC TO CROSS FAK AT 10000 FT. THE FO CONFIRMED THAT 10000 FT WAS OUR CLRED ALT. THE CLRNC WAS RECEIVED ON A FREQ OF 127.75. I READ BACK THE CLRED ALT TO THE CTLR. WE WERE HANDED OFF TO THE NEXT CTLR ON 132.77. WHEN I CHKED IN I STATED THAT WE WERE DSNDING THROUGH FL200 TO AN ASSIGNED ALT OF 10000 FT. THE CTLR ASKED ME TO REPEAT OUR CLRED ALT. WHEN I REPEATED '10000 FT', THE CTLR STATED THAT OUR CLRED ALT WAS FL200. THE LOWEST ALT REACHED WAS FL190, WE CLBED BACK UP TO FL200. NO APPARENT LOSS OF SEPARATION TOOK PLACE. FACTORS AFFECTING THE QUALITY OF HUMAN PERFORMANCE: THE FO WAS NEW TO THE AIRPLANE AND TO OUR COMPANY. I WAS HELPING HIM WITH PROGRAMMING THE FMC SYS. I SHOULD HAVE BEEN SUSPICIOUS OF A CLRNC TO SUCH A LOW ALT CONSIDERING THE DISTANCE FROM THE DEST. I ALSO SHOULD HAVE QUESTIONED A CLRNC TO AN 'MSL' ALT WITHOUT AN ALTIMETER SETTING BEING GIVEN. THE CTLR MAY HAVE MISSTATED THE ALT. IF HE STATED THE ALT CORRECTLY, HE SHOULD HAVE HEARD MY INCORRECT READBACK.

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.