After experiencing some difficulty programming a clearance to descend to FL240 the captain of a B737...

Attributes
ACN	1114284
Time
Date	201309
Local Time Of Day	1201-1800
Place
Locale Reference	ZMA.ARTCC
State Reference	FL
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 143
Events
Anomaly	Airspace Violation All Types Deviation - Altitude Undershoot Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Narrative:

We were given clearance to descend to FL240 from an altitude higher than FL310. As we began the descent; VNAV would not engage. I tried to enter a lower altitude so the VNAV would engage. The altitude I entered into the FMC was FL300. I thought we were all set and the descent was occurring. I later noticed we had climbed from about FL276 to FL300. We were supposed to be descending to FL240. After I noticed the aircraft level off at FL300; I immediately used vertical speed (V/south) to continue the descent. ATC did not notify us of the possible deviation. I think we should have monitored our FMC entries better. This would have prevented what occurred.

Original NASA ASRS Text

Title: After experiencing some difficulty programming a clearance to descend to FL240 the Captain of a B737-700 realized that; instead of descending; the aircraft had climbed from approximately FL276 to FL300 where it had leveled.

Narrative: We were given clearance to descend to FL240 from an altitude higher than FL310. As we began the descent; VNAV would not engage. I tried to enter a lower altitude so the VNAV would engage. The altitude I entered into the FMC was FL300. I thought we were all set and the descent was occurring. I later noticed we had climbed from about FL276 to FL300. We were supposed to be descending to FL240. After I noticed the aircraft level off at FL300; I immediately used Vertical Speed (V/S) to continue the descent. ATC did not notify us of the possible deviation. I think we should have monitored our FMC entries better. This would have prevented what occurred.

Data retrieved from NASA's ASRS site as of July 2013 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.

After experiencing some difficulty programming a clearance to descend to FL240 the captain of a B737-700 realized that; instead of descending; the aircraft had climbed from approximately FL276 to FL300 where it had leveled.