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A B757 flight crew catches an error in the auxiliary altimeter of being 1000 ft off the correct altimeter setting on descent into bhm, al.
| Attributes | |
| ACN | 506729 |
| Time | |
| Date | 200104 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : bhm.airport |
| State Reference | AL |
| Altitude | msl single value : 18000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : ztl.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : approach |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 20000 flight time type : 2000 |
| ASRS Report | 506729 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | aircraft equipment problem : less severe non adherence : published procedure non adherence : company policies |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : became reoriented flight crew : overcame equipment problem |
| Consequence | other |
| Factors | |
| Maintenance | contributing factor : engineering procedure performance deficiency : scheduled maintenance performance deficiency : testing |
| Supplementary | |
| Problem Areas | Maintenance Human Performance Flight Crew Human Performance Company |
| Primary Problem | Flight Crew Human Performance |
Narrative:
Normal preflight of aircraft conducted. All phases of flight normal until descent checklist at FL180 into bhm. Altimeter setting 29.83. First officer noticed my auxiliary altimeter at 28.83 (1000 ft low). I reset it and he advised that on preflight his altimeter was also 1000 ft low. (When I preflted, I set the correct altimeter in my primary altimeter noticing all 4 digits. The altitude changed approximately 60 ft. I then set my auxiliary altimeter and only observed the last 2 digits, but the altitude also changed approximately 60 ft. In reality it was 1060 ft off.) no altitudes were busted since both primary altimeters were set correctly. However, the possibility of serious consequences are obvious. Later, my chief pilot (on follow-up) said that maintenance had zeroed the altimeters as a standard procedure and only reset the captain's primary altimeter to the correct altimeter setting. This was in atlanta, altitude 1026 ft MSL. (I was concerned that someone had messed with altimeters deliberately.) from now on, I will be observant to read all 4 digits all the time.
Original NASA ASRS Text
Title: A B757 FLC CATCHES AN ERROR IN THE AUX ALTIMETER OF BEING 1000 FT OFF THE CORRECT ALTIMETER SETTING ON DSCNT INTO BHM, AL.
Narrative: NORMAL PREFLT OF ACFT CONDUCTED. ALL PHASES OF FLT NORMAL UNTIL DSCNT CHKLIST AT FL180 INTO BHM. ALTIMETER SETTING 29.83. FO NOTICED MY AUX ALTIMETER AT 28.83 (1000 FT LOW). I RESET IT AND HE ADVISED THAT ON PREFLT HIS ALTIMETER WAS ALSO 1000 FT LOW. (WHEN I PREFLTED, I SET THE CORRECT ALTIMETER IN MY PRIMARY ALTIMETER NOTICING ALL 4 DIGITS. THE ALT CHANGED APPROX 60 FT. I THEN SET MY AUX ALTIMETER AND ONLY OBSERVED THE LAST 2 DIGITS, BUT THE ALT ALSO CHANGED APPROX 60 FT. IN REALITY IT WAS 1060 FT OFF.) NO ALTS WERE BUSTED SINCE BOTH PRIMARY ALTIMETERS WERE SET CORRECTLY. HOWEVER, THE POSSIBILITY OF SERIOUS CONSEQUENCES ARE OBVIOUS. LATER, MY CHIEF PLT (ON FOLLOW-UP) SAID THAT MAINT HAD ZEROED THE ALTIMETERS AS A STANDARD PROC AND ONLY RESET THE CAPT'S PRIMARY ALTIMETER TO THE CORRECT ALTIMETER SETTING. THIS WAS IN ATLANTA, ALT 1026 FT MSL. (I WAS CONCERNED THAT SOMEONE HAD MESSED WITH ALTIMETERS DELIBERATELY.) FROM NOW ON, I WILL BE OBSERVANT TO READ ALL 4 DIGITS ALL THE TIME.
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.