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Captain's altimeter (coupled to the autoplt) not set in transition through FL180 to 17000 ft leading to altitude deviation.
| Attributes | |
| ACN | 294694 |
| Time | |
| Date | 199501 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : lrp |
| State Reference | PA |
| Altitude | msl bound lower : 16750 msl bound upper : 17000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Route In Use | enroute airway : zny |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 180 flight time total : 4000 flight time type : 1000 |
| ASRS Report | 294694 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance non adherence other |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
I had taken the last break on an atlantic wbound crossing as PF (which is not the best situation, however, the captain had taken the middle break), so I had just come back to the cockpit as it was time to start the descent. I was trying to get up to speed as a flight attendant came up to discuss a cabin problem. I told her I could not talk any more about it at that time, I was too busy. At that time, we were given a descent from FL200 to 17000 ft. I had not looked at the ATIS the captain had written down or heard the altimeter setting from the controller due to the conversation with the flight attendant. Going through FL180 I looked to the standby altimeter for the setting and the captain had not set it there as is customary either. By the time I looked at the ATIS the controller repeated the local altimeter as 29.17 (ATIS showed 29.30). The autoplt was flying with an approximately 2000 FPM descent rate. As soon as I started spinning the altimeter setting in my side (the captain had yet to set either of his) I realized the autoplt would capture based on the captain's altimeter (greater than 700 ft too low). I disconnected the autoplt and leveled off based on my altimeter as gently as I could without upsetting the cabin. This took me to 16750 ft MSL (250 ft low). I established 17000 ft level and when the captain had set his altimeters I reengaged the autoplt and tried to regain my composure (not easy, I pride myself on thinking ahead of the airplane and captain). Several things could have avoided this problem: 1) not allowing the flight attendant to discuss anything after the top of descent. 2) an autoplt that follows the aim of 1000 FPM rate in the last 1000 ft of descent. 3) the captain could have brought the low altimeter setting to my attention after listening to the ATIS. 4) start looking for altimeter setting leaving FL200 instead of FL180. 5) even changing mode on autoplt to vertical speed -- 1000 FPM -- during last 1000 ft of descent.
Original NASA ASRS Text
Title: CAPT'S ALTIMETER (COUPLED TO THE AUTOPLT) NOT SET IN TRANSITION THROUGH FL180 TO 17000 FT LEADING TO ALTDEV.
Narrative: I HAD TAKEN THE LAST BREAK ON AN ATLANTIC WBOUND XING AS PF (WHICH IS NOT THE BEST SIT, HOWEVER, THE CAPT HAD TAKEN THE MIDDLE BREAK), SO I HAD JUST COME BACK TO THE COCKPIT AS IT WAS TIME TO START THE DSCNT. I WAS TRYING TO GET UP TO SPD AS A FLT ATTENDANT CAME UP TO DISCUSS A CABIN PROB. I TOLD HER I COULD NOT TALK ANY MORE ABOUT IT AT THAT TIME, I WAS TOO BUSY. AT THAT TIME, WE WERE GIVEN A DSCNT FROM FL200 TO 17000 FT. I HAD NOT LOOKED AT THE ATIS THE CAPT HAD WRITTEN DOWN OR HEARD THE ALTIMETER SETTING FROM THE CTLR DUE TO THE CONVERSATION WITH THE FLT ATTENDANT. GOING THROUGH FL180 I LOOKED TO THE STANDBY ALTIMETER FOR THE SETTING AND THE CAPT HAD NOT SET IT THERE AS IS CUSTOMARY EITHER. BY THE TIME I LOOKED AT THE ATIS THE CTLR REPEATED THE LCL ALTIMETER AS 29.17 (ATIS SHOWED 29.30). THE AUTOPLT WAS FLYING WITH AN APPROX 2000 FPM DSCNT RATE. AS SOON AS I STARTED SPINNING THE ALTIMETER SETTING IN MY SIDE (THE CAPT HAD YET TO SET EITHER OF HIS) I REALIZED THE AUTOPLT WOULD CAPTURE BASED ON THE CAPT'S ALTIMETER (GREATER THAN 700 FT TOO LOW). I DISCONNECTED THE AUTOPLT AND LEVELED OFF BASED ON MY ALTIMETER AS GENTLY AS I COULD WITHOUT UPSETTING THE CABIN. THIS TOOK ME TO 16750 FT MSL (250 FT LOW). I ESTABLISHED 17000 FT LEVEL AND WHEN THE CAPT HAD SET HIS ALTIMETERS I REENGAGED THE AUTOPLT AND TRIED TO REGAIN MY COMPOSURE (NOT EASY, I PRIDE MYSELF ON THINKING AHEAD OF THE AIRPLANE AND CAPT). SEVERAL THINGS COULD HAVE AVOIDED THIS PROB: 1) NOT ALLOWING THE FLT ATTENDANT TO DISCUSS ANYTHING AFTER THE TOP OF DSCNT. 2) AN AUTOPLT THAT FOLLOWS THE AIM OF 1000 FPM RATE IN THE LAST 1000 FT OF DSCNT. 3) THE CAPT COULD HAVE BROUGHT THE LOW ALTIMETER SETTING TO MY ATTN AFTER LISTENING TO THE ATIS. 4) START LOOKING FOR ALTIMETER SETTING LEAVING FL200 INSTEAD OF FL180. 5) EVEN CHANGING MODE ON AUTOPLT TO VERT SPD -- 1000 FPM -- DURING LAST 1000 FT OF DSCNT.
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.