An air carrier crosses a fix 1000 ft below the required altitude due to an altimeter setting error.

Attributes
ACN	565643
Time
Date	200211
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : ftz.vortac
State Reference	MO
Altitude	msl single value : 14000
Environment
Flight Conditions	Mixed
Weather Elements	Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : t75.tracon
Operator	common carrier : air carrier
Make Model Name	MD-82
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : trake 8
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 4700 flight time type : 1800
ASRS Report	565643
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : crossing restriction not met altitude deviation : overshoot non adherence : clearance non adherence : far other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Supplementary
Problem Areas	Flight Crew Human Performance Environmental Factor
Primary Problem	Flight Crew Human Performance

Narrative:

After programming performance management system (pms) for descent, we were beginning descent to assigned crossing altitude of 15000 ft at kayla arc (trake arrival). ATC cleared us direct to ftz, resulting in steep descent to try to make crossing. We encountered moderate turbulence and had to slow to turbulence penetration speed, further exacerbating descent problem. Concerned with being high at fix, captain was attempting to maximize descent while first officer was performing checklists and alerting cabin per policy. After leveling at 15000 ft it was noticed that altimeter had been set with a 1 inch difference (captain 30.47 inches, first officer 29.47 inches), resulting in actual aircraft altitude of 14000 ft MSL (local altimeter 29.47 inches). Because captain was PF, autoplt was using air data and altitude reporting from #1 system. It seems likely that, since #1 transponder was reporting 15000 ft altitude to ATC, approach control didn't notice altitude discrepancy. Error was discovered at completion of descent/approach checklist after leveloff. We were subsequently cleared to 7000 ft and commenced descent before having a chance to correct back up to 15000 ft.

Original NASA ASRS Text

Title: AN ACR CROSSES A FIX 1000 FT BELOW THE REQUIRED ALT DUE TO AN ALTIMETER SETTING ERROR.

Narrative: AFTER PROGRAMMING PERFORMANCE MGMNT SYS (PMS) FOR DSCNT, WE WERE BEGINNING DSCNT TO ASSIGNED XING ALT OF 15000 FT AT KAYLA ARC (TRAKE ARR). ATC CLRED US DIRECT TO FTZ, RESULTING IN STEEP DSCNT TO TRY TO MAKE XING. WE ENCOUNTERED MODERATE TURB AND HAD TO SLOW TO TURB PENETRATION SPD, FURTHER EXACERBATING DSCNT PROB. CONCERNED WITH BEING HIGH AT FIX, CAPT WAS ATTEMPTING TO MAXIMIZE DSCNT WHILE FO WAS PERFORMING CHKLISTS AND ALERTING CABIN PER POLICY. AFTER LEVELING AT 15000 FT IT WAS NOTICED THAT ALTIMETER HAD BEEN SET WITH A 1 INCH DIFFERENCE (CAPT 30.47 INCHES, FO 29.47 INCHES), RESULTING IN ACTUAL ACFT ALT OF 14000 FT MSL (LCL ALTIMETER 29.47 INCHES). BECAUSE CAPT WAS PF, AUTOPLT WAS USING AIR DATA AND ALT RPTING FROM #1 SYS. IT SEEMS LIKELY THAT, SINCE #1 XPONDER WAS RPTING 15000 FT ALT TO ATC, APCH CTL DIDN'T NOTICE ALT DISCREPANCY. ERROR WAS DISCOVERED AT COMPLETION OF DSCNT/APCH CHKLIST AFTER LEVELOFF. WE WERE SUBSEQUENTLY CLRED TO 7000 FT AND COMMENCED DSCNT BEFORE HAVING A CHANCE TO CORRECT BACK UP TO 15000 FT.

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.