An MD88 crew with an inoperative horizontal stabilizer trim mistakenly completed the 'mach trim inoperative' checklist and got the trim partially operational.

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Attributes
ACN	668367
Time
Date	200505
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : atl.airport
State Reference	GA
Altitude	msl bound lower : 10000 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : a80.tracon
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 8000 flight time type : 1700
ASRS Report	668367
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : anomaly accepted
Consequence	other
Supplementary
Problem Areas	Aircraft Chart Or Publication Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

On climb out of atl; autoplt would not engage. We switched to and tried dfgc #1; but the autoplt would still not engage. Primary trim also would not operate with thumb switches or suitcase handles. We found that trim was available by using the alternate trim switch. I hand flew the aircraft and was communicating with ATC while the captain was looking through the QRH. He said he was turning off the mach trim compensator per the checklist. Primary trim was restored but the autoplt would still not engage. I know he conversed with maintenance and flight control through the ACARS several times for assistance. After deplaning at jax; the captain and I discussed the events of the flight. I then found out that we were on the 'mach trim inoperative' checklist. I asked how we got there; and he said that he was looking for anything that addressed 'trim.' I did not know we were running an incorrect procedure. I just thought it was part of the correct procedure since I was busy flying and communicating with ATC.

Original NASA ASRS Text

Title: AN MD88 CREW WITH AN INOP HORIZ STABILIZER TRIM MISTAKENLY COMPLETED THE 'MACH TRIM INOP' CHKLIST AND GOT THE TRIM PARTIALLY OPERATIONAL.

Narrative: ON CLBOUT OF ATL; AUTOPLT WOULD NOT ENGAGE. WE SWITCHED TO AND TRIED DFGC #1; BUT THE AUTOPLT WOULD STILL NOT ENGAGE. PRIMARY TRIM ALSO WOULD NOT OPERATE WITH THUMB SWITCHES OR SUITCASE HANDLES. WE FOUND THAT TRIM WAS AVAILABLE BY USING THE ALTERNATE TRIM SWITCH. I HAND FLEW THE ACFT AND WAS COMMUNICATING WITH ATC WHILE THE CAPT WAS LOOKING THROUGH THE QRH. HE SAID HE WAS TURNING OFF THE MACH TRIM COMPENSATOR PER THE CHKLIST. PRIMARY TRIM WAS RESTORED BUT THE AUTOPLT WOULD STILL NOT ENGAGE. I KNOW HE CONVERSED WITH MAINT AND FLT CTL THROUGH THE ACARS SEVERAL TIMES FOR ASSISTANCE. AFTER DEPLANING AT JAX; THE CAPT AND I DISCUSSED THE EVENTS OF THE FLT. I THEN FOUND OUT THAT WE WERE ON THE 'MACH TRIM INOP' CHKLIST. I ASKED HOW WE GOT THERE; AND HE SAID THAT HE WAS LOOKING FOR ANYTHING THAT ADDRESSED 'TRIM.' I DID NOT KNOW WE WERE RUNNING AN INCORRECT PROC. I JUST THOUGHT IT WAS PART OF THE CORRECT PROC SINCE I WAS BUSY FLYING AND COMMUNICATING WITH ATC.

Data retrieved from NASA's ASRS site as of January 2009 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.