A B737-800 autothrottle disconnected on final prior to 1;000 ft but went undetected the until 1;000 ...

Narrative:

On final approach to runway 09L the captain asked for and was approved for a sidestep to runway 09R. This was approximately 2;000 ft MSL while on a VFR localizer approach. The sidestep was performed normally by me. At approximately 1;000 ft; or slightly lower; I noticed the autothrottles had disengaged for some reason and the airspeed had bled off to approximately 7 or 8 KTS below vref. I subsequently manually added power and lowered the aircraft nose. The required speed was regained; but the aircraft was slightly high on the glide slope now. I further lowered the nose and was able to get back on path around 500 ft. The landing was normal; if slightly long; after that. A go around maneuver would have been the more prudent decision for this approach.when it was discovered that the autothrottles has disengaged; then a go-around should have been initiated.

Original NASA ASRS Text

Title: A B737-800 autothrottle disconnected on final prior to 1;000 FT but went undetected the until 1;000 FT; about 7 KTS below VRef; and during recovery the aircraft went above glideslope and finally landed long.

Narrative: On final approach to Runway 09L the Captain asked for and was approved for a sidestep to Runway 09R. This was approximately 2;000 FT MSL while on a VFR LOC approach. The sidestep was performed normally by me. At approximately 1;000 FT; or slightly lower; I noticed the autothrottles had disengaged for some reason and the airspeed had bled off to approximately 7 or 8 KTS below VREF. I subsequently manually added power and lowered the aircraft nose. The required speed was regained; but the aircraft was slightly high on the glide slope now. I further lowered the nose and was able to get back on path around 500 FT. The landing was normal; if slightly long; after that. A go around maneuver would have been the more prudent decision for this approach.When it was discovered that the autothrottles has disengaged; then a go-around should have been initiated.

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.

Attributes
ACN	1121745
Time
Date	201310
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Speed All Types Inflight Event / Encounter Unstabilized Approach

A B737-800 autothrottle disconnected on final prior to 1;000 ft but went undetected the until 1;000 ft; about 7 KTS below vref; and during recovery the aircraft went above glideslope and finally landed long.