B737-400 misses crossing restr into pit. Blames software and tailwinds.

Attributes
ACN	458105
Time
Date	199912
Day	Sat
Local Time Of Day	1201 To 1800
Place
State Reference	PA
Altitude	msl single value : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude descent other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 220 flight time total : 11000 flight time type : 6000
ASRS Report	458105
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : crossing restriction not met inflight encounter other non adherence : far non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : altimeter other controllera other flight crewa
Resolutory Action	controller : issued alert controller : issued advisory
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft Environmental Factor
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were inbound to pit from south and had approximately 90 KT tailwind. We were level cruise at FL310 and approximately 130 NM from ihd and given crossing restr ihd/100 DME at FL240. We acknowledged and entered the 'new' fix into FMC. However, this version of the software would not let us enter the restr altitude FL240. As I was PNF, I tried several ways to enter the altitude and did not 'monitor' our distance to the fix as I should (usually) do. Because of our tailwind the distance closed rapidly. ATC called at about 10-12 mi from the fix and asked if we were going to 'make the restr.' I responded that it would be close and asked first officer to use speed brake and 'dump' the aircraft. ATC advised to 'call out of FL280' for traffic, which was no problem. But we were only FL250 descending at 100 ihd. I don't know why this software problem can't be fixed. Cost? But I know it has caused problems before and will again until it is updated to allow altitude entries on the cruise line. Constant monitoring of position is necessary, possible normally done, but I let my guard down and the abnormal tailwind aggravated the situation.

Original NASA ASRS Text

Title: B737-400 MISSES XING RESTR INTO PIT. BLAMES SOFTWARE AND TAILWINDS.

Narrative: WE WERE INBOUND TO PIT FROM S AND HAD APPROX 90 KT TAILWIND. WE WERE LEVEL CRUISE AT FL310 AND APPROX 130 NM FROM IHD AND GIVEN XING RESTR IHD/100 DME AT FL240. WE ACKNOWLEDGED AND ENTERED THE 'NEW' FIX INTO FMC. HOWEVER, THIS VERSION OF THE SOFTWARE WOULD NOT LET US ENTER THE RESTR ALT FL240. AS I WAS PNF, I TRIED SEVERAL WAYS TO ENTER THE ALT AND DID NOT 'MONITOR' OUR DISTANCE TO THE FIX AS I SHOULD (USUALLY) DO. BECAUSE OF OUR TAILWIND THE DISTANCE CLOSED RAPIDLY. ATC CALLED AT ABOUT 10-12 MI FROM THE FIX AND ASKED IF WE WERE GOING TO 'MAKE THE RESTR.' I RESPONDED THAT IT WOULD BE CLOSE AND ASKED FO TO USE SPD BRAKE AND 'DUMP' THE ACFT. ATC ADVISED TO 'CALL OUT OF FL280' FOR TFC, WHICH WAS NO PROB. BUT WE WERE ONLY FL250 DSNDING AT 100 IHD. I DON'T KNOW WHY THIS SOFTWARE PROB CAN'T BE FIXED. COST? BUT I KNOW IT HAS CAUSED PROBS BEFORE AND WILL AGAIN UNTIL IT IS UPDATED TO ALLOW ALT ENTRIES ON THE CRUISE LINE. CONSTANT MONITORING OF POS IS NECESSARY, POSSIBLE NORMALLY DONE, BUT I LET MY GUARD DOWN AND THE ABNORMAL TAILWIND AGGRAVATED THE SIT.

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.