Altitude deviation altitude overshot.

Attributes
ACN	237448
Time
Date	199303
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : cll
State Reference	TX
Altitude	msl bound lower : 27000 msl bound upper : 29000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu tower : dsm
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : atp pilot : commercial pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 16000 flight time type : 13000
ASRS Report	237448
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	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	controller : issued new clearance flight crew : exited adverse environment
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was PIC from dal to hou. I was flying the aircraft during climb out when the first officer checked off frequency to get the ATIS while I was climbing to 23000 ft. I received clearance (I thought) to FL290. I responded and set 290 in my altitude alert. As we were climbing to FL270, the first officer checked back on and asked if I was sure that the clearance was to FL290. He thought it was to FL270. Since he had checked off, I did not think he had heard the clearance, so I assured him that we had been cleared to FL290. After leveling at FL290, I started having second thoughts and started watching the TCASII for possible conflicting traffic. Shortly, I saw an aircraft come into view 15 mi ahead crossing right to left. I told the first officer to tell center that we were at FL290. He did so, and center immediately cleared us to FL270 and to expedite out of FL280. We complied and leveled at FL270 more than 10 mi from the TCASII target. I did not know that the first officer had heard the clearance even though he was copying the ATIS. He thought he had heard FL270 and indications are that he was probably right. I should have leveled at FL270 and confirmed the clearance. I am still not absolutely certain that we leveled at the wrong altitude and I don't know if I read back 270 or 290. This was a case however, when the TCASII proved very useful in averting what could have been a conflict.

Original NASA ASRS Text

Title: ALTDEV ALT OVERSHOT.

Narrative: I WAS PIC FROM DAL TO HOU. I WAS FLYING THE ACFT DURING CLBOUT WHEN THE FO CHKED OFF FREQ TO GET THE ATIS WHILE I WAS CLBING TO 23000 FT. I RECEIVED CLRNC (I THOUGHT) TO FL290. I RESPONDED AND SET 290 IN MY ALT ALERT. AS WE WERE CLBING TO FL270, THE FO CHKED BACK ON AND ASKED IF I WAS SURE THAT THE CLRNC WAS TO FL290. HE THOUGHT IT WAS TO FL270. SINCE HE HAD CHKED OFF, I DID NOT THINK HE HAD HEARD THE CLRNC, SO I ASSURED HIM THAT WE HAD BEEN CLRED TO FL290. AFTER LEVELING AT FL290, I STARTED HAVING SECOND THOUGHTS AND STARTED WATCHING THE TCASII FOR POSSIBLE CONFLICTING TFC. SHORTLY, I SAW AN ACFT COME INTO VIEW 15 MI AHEAD XING R TO L. I TOLD THE FO TO TELL CTR THAT WE WERE AT FL290. HE DID SO, AND CTR IMMEDIATELY CLRED US TO FL270 AND TO EXPEDITE OUT OF FL280. WE COMPLIED AND LEVELED AT FL270 MORE THAN 10 MI FROM THE TCASII TARGET. I DID NOT KNOW THAT THE FO HAD HEARD THE CLRNC EVEN THOUGH HE WAS COPYING THE ATIS. HE THOUGHT HE HAD HEARD FL270 AND INDICATIONS ARE THAT HE WAS PROBABLY RIGHT. I SHOULD HAVE LEVELED AT FL270 AND CONFIRMED THE CLRNC. I AM STILL NOT ABSOLUTELY CERTAIN THAT WE LEVELED AT THE WRONG ALT AND I DON'T KNOW IF I READ BACK 270 OR 290. THIS WAS A CASE HOWEVER, WHEN THE TCASII PROVED VERY USEFUL IN AVERTING WHAT COULD HAVE BEEN A CONFLICT.

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.