|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1201 To 1800|
|Locale Reference||atc facility : bvl|
|Altitude||msl bound lower : 24000|
msl bound upper : 24600
|Controlling Facilities||artcc : zlc|
|Operator||common carrier : air carrier|
|Make Model Name||Medium Large Transport, Low Wing, 2 Turbojet Eng|
|Flight Phase||climbout : intermediate altitude|
|Route In Use||enroute : on vectors|
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Qualification||pilot : atp|
|Experience||flight time last 90 days : 70|
flight time total : 16500
flight time type : 1000
|Function||flight crew : first officer|
|Qualification||pilot : commercial|
pilot : instrument
|Anomaly||altitude deviation : overshoot|
other anomaly other
|Independent Detector||other controllera|
|Resolutory Action||controller : issued new clearance|
|Primary Problem||Flight Crew Human Performance|
|Air Traffic Incident||Pilot Deviation|
Altitude clearance was FL240. At 17500 ft I reset the captain's altimeter to 29.92 and verbally called '29.92' as per company procedures. Shortly after level off, center asked us to verify our altitude. It was then noticed that my (captain) altimeter read FL240, while the first officer's read FL246. Center immediately cleared us to climb to FL290 and we then continued our climb. The problem was caused by my setting 992 in the millibar window on the captain's altimeter by mistake, instead of 29.92 in the inches window. A contributing factor to this was the fact that this particular aircraft is a nonstandard variant in the company fleet. Among several differences is the captain's altimeter which has the millibar and in hg windows reversed from most of the rest of the fleet. (The usual position is MB-lower left, and in hg-lower right. This aircraft has millibars-lower right and in hg lower left). Also, the 'MB' and 'in hg' captions above the respective windows are missing on this particular altimeter. Standardization of instrument face presentations would help prevent this type of incident, I would think. We tend to do things from habit patterns instead of actually noticing details which may differ from the norm.
Original NASA ASRS Text
Title: SET MILLIBARS VERSUS INCHES ON THE CAPT ALTIMETER, RESULTING IN OFF ALT 600 FEET.
Narrative: ALTITUDE CLRNC WAS FL240. AT 17500 FT I RESET THE CAPT'S ALTIMETER TO 29.92 AND VERBALLY CALLED '29.92' AS PER COMPANY PROCEDURES. SHORTLY AFTER LEVEL OFF, CENTER ASKED US TO VERIFY OUR ALTITUDE. IT WAS THEN NOTICED THAT MY (CAPT) ALTIMETER READ FL240, WHILE THE FIRST OFFICER'S READ FL246. CENTER IMMEDIATELY CLRED US TO CLIMB TO FL290 AND WE THEN CONTINUED OUR CLIMB. THE PROBLEM WAS CAUSED BY MY SETTING 992 IN THE MILLIBAR WINDOW ON THE CAPTAIN'S ALTIMETER BY MISTAKE, INSTEAD OF 29.92 IN THE INCHES WINDOW. A CONTRIBUTING FACTOR TO THIS WAS THE FACT THAT THIS PARTICULAR ACFT IS A NONSTANDARD VARIANT IN THE COMPANY FLEET. AMONG SEVERAL DIFFERENCES IS THE CAPTAIN'S ALTIMETER WHICH HAS THE MILLIBAR AND IN HG WINDOWS REVERSED FROM MOST OF THE REST OF THE FLEET. (THE USUAL POSITION IS MB-LOWER LEFT, AND IN HG-LOWER RIGHT. THIS ACFT HAS MILLIBARS-LOWER RIGHT AND IN HG LOWER LEFT). ALSO, THE 'MB' AND 'IN HG' CAPTIONS ABOVE THE RESPECTIVE WINDOWS ARE MISSING ON THIS PARTICULAR ALTIMETER. STANDARDIZATION OF INSTRUMENT FACE PRESENTATIONS WOULD HELP PREVENT THIS TYPE OF INCIDENT, I WOULD THINK. WE TEND TO DO THINGS FROM HABIT PATTERNS INSTEAD OF ACTUALLY NOTICING DETAILS WHICH MAY DIFFER FROM THE NORM.
Data retrieved from NASA's ASRS site as of August 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.