Narrative:

On the janesville 4 arrival to ord, after receiving clearance to FL180 to enter holding at teddy and programming the FMS, as the PNF, I turned over ATC communication duties to the first officer while I made the required radio calls to company operations and get updated WX. The first officer got clearance to descend to 16000 ft and was given an altimeter setting which he stated he read back as 30.53. (Actual setting was 29.53.) the aircraft leveled at 16000 ft on the first officer altimeter (15000 ft actual altitude) as he made a call to ATC reporting entering holding at 16000 ft. The controller questioned the altitude and after some discussion between ATC and the first officer the altimeter setting error was discovered. The first officer started an immediate climb and reset his altimeter, setting off the altitude warning which got my attention just as ATC was confirming that we should climb back to 16000 ft. It is, of course, always preferable for the PNF to backup the PF, but in a 2-MAN cockpit, that is just not always possible. Still, extra diligence is required from both pilots when one must divert his attention to non flying duties. There also seems to be developing among pilots and controllers a decreased attention to altimeter settings. Pilots sometimes do not receive and often do not read back altimeter settings and erroneous readbacks are often not challenged. With jet aircraft spending very little level flight time below FL180 and with most approachs ending in a visual approach, altimeter setting errors usually do not result in significant or dangerous altdevs. But there are times when altimeter setting errors are large enough to cause significant altdevs and still seem to be settings in the 'reasonable range.'

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Original NASA ASRS Text

Title: A MISSET ALTIMETER ON AN MD90 CAUSES THE ACFT TO BE FLOWN 1000 FT LOW IN THE HOLDING PATTERN.

Narrative: ON THE JANESVILLE 4 ARR TO ORD, AFTER RECEIVING CLRNC TO FL180 TO ENTER HOLDING AT TEDDY AND PROGRAMMING THE FMS, AS THE PNF, I TURNED OVER ATC COM DUTIES TO THE FO WHILE I MADE THE REQUIRED RADIO CALLS TO COMPANY OPS AND GET UPDATED WX. THE FO GOT CLRNC TO DSND TO 16000 FT AND WAS GIVEN AN ALTIMETER SETTING WHICH HE STATED HE READ BACK AS 30.53. (ACTUAL SETTING WAS 29.53.) THE ACFT LEVELED AT 16000 FT ON THE FO ALTIMETER (15000 FT ACTUAL ALT) AS HE MADE A CALL TO ATC RPTING ENTERING HOLDING AT 16000 FT. THE CTLR QUESTIONED THE ALT AND AFTER SOME DISCUSSION BTWN ATC AND THE FO THE ALTIMETER SETTING ERROR WAS DISCOVERED. THE FO STARTED AN IMMEDIATE CLB AND RESET HIS ALTIMETER, SETTING OFF THE ALT WARNING WHICH GOT MY ATTN JUST AS ATC WAS CONFIRMING THAT WE SHOULD CLB BACK TO 16000 FT. IT IS, OF COURSE, ALWAYS PREFERABLE FOR THE PNF TO BACKUP THE PF, BUT IN A 2-MAN COCKPIT, THAT IS JUST NOT ALWAYS POSSIBLE. STILL, EXTRA DILIGENCE IS REQUIRED FROM BOTH PLTS WHEN ONE MUST DIVERT HIS ATTN TO NON FLYING DUTIES. THERE ALSO SEEMS TO BE DEVELOPING AMONG PLTS AND CTLRS A DECREASED ATTN TO ALTIMETER SETTINGS. PLTS SOMETIMES DO NOT RECEIVE AND OFTEN DO NOT READ BACK ALTIMETER SETTINGS AND ERRONEOUS READBACKS ARE OFTEN NOT CHALLENGED. WITH JET ACFT SPENDING VERY LITTLE LEVEL FLT TIME BELOW FL180 AND WITH MOST APCHS ENDING IN A VISUAL APCH, ALTIMETER SETTING ERRORS USUALLY DO NOT RESULT IN SIGNIFICANT OR DANGEROUS ALTDEVS. BUT THERE ARE TIMES WHEN ALTIMETER SETTING ERRORS ARE LARGE ENOUGH TO CAUSE SIGNIFICANT ALTDEVS AND STILL SEEM TO BE SETTINGS IN THE 'REASONABLE RANGE.'

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.