B737 crew lowers landing gear at gear extended limit instead of gear extension limit.

Attributes
ACN	442971
Time
Date	199907
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mslp.airport
State Reference	FO
Altitude	msl single value : 13000
Environment
Flight Conditions	IMC
Light	Dusk
Aircraft 1
Controlling Facilities	tracon : mslp.tracon
Operator	common carrier : air carrier
Make Model Name	B737-600, -700, -800
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain
Qualification	pilot : cfi pilot : atp pilot : multi engine
Experience	flight time last 90 days : 150 flight time total : 6800 flight time type : 1500
ASRS Report	442971
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : commercial pilot : atp pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 95.5 flight time total : 2131 flight time type : 95.5
ASRS Report	442801
Events
Anomaly	aircraft equipment problem : critical non adherence : company policies non adherence : far non adherence : published procedure other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

An FMS/VNAV descent was used to begin the descent from cruise altitude. Passing about 24000 ft it was determined that the descent rate was not adequate. A non-VNAV descent mode was activated and spoilers were extended. Workload was high due to IMC conditions, high terrain in the area, an arcing transition, no ATIS available, and foreign language controller communication. In an effort to descend and slow for the approach the first officer and I agreed that gear extension was necessary. We both referred to the landing gear limit speed placard to determine the limit speed. We both read the gear extended speed of 320 KTS and lowered the gear at approximately 300 KTS. After departure from msal and during cruise on the return flight, the first officer and I were discussing the previous arrival. At that time we noticed the correct gear limit speed for extension of 270 KTS. An appropriate logbook entry was made.

Original NASA ASRS Text

Title: B737 CREW LOWERS LNDG GEAR AT GEAR EXTENDED LIMIT INSTEAD OF GEAR EXTENSION LIMIT.

Narrative: AN FMS/VNAV DSCNT WAS USED TO BEGIN THE DSCNT FROM CRUISE ALT. PASSING ABOUT 24000 FT IT WAS DETERMINED THAT THE DSCNT RATE WAS NOT ADEQUATE. A NON-VNAV DSCNT MODE WAS ACTIVATED AND SPOILERS WERE EXTENDED. WORKLOAD WAS HIGH DUE TO IMC CONDITIONS, HIGH TERRAIN IN THE AREA, AN ARCING TRANSITION, NO ATIS AVAILABLE, AND FOREIGN LANGUAGE CTLR COM. IN AN EFFORT TO DSND AND SLOW FOR THE APCH THE FO AND I AGREED THAT GEAR EXTENSION WAS NECESSARY. WE BOTH REFERRED TO THE LNDG GEAR LIMIT SPD PLACARD TO DETERMINE THE LIMIT SPD. WE BOTH READ THE GEAR EXTENDED SPD OF 320 KTS AND LOWERED THE GEAR AT APPROX 300 KTS. AFTER DEP FROM MSAL AND DURING CRUISE ON THE RETURN FLT, THE FO AND I WERE DISCUSSING THE PREVIOUS ARR. AT THAT TIME WE NOTICED THE CORRECT GEAR LIMIT SPD FOR EXTENSION OF 270 KTS. AN APPROPRIATE LOGBOOK ENTRY WAS MADE.

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.