An air carrier first officer reported feeling low on approach about 15 NM from ama and realized he w...

Narrative:

At 5;000 ft MSL roughly 15 nm southeast runway 31 at ama we accepted a visual via direct imobe then runway 31. We don't have a RNAV 31 chart but it's in the database. We had previously been given direct from fuz to ama and that put us just a little east of the final for 31. We flew to imobe in LNAV and I selected 4;200 ft in the MCP and started to descend via V/south. I was tired and just assumed we were in class B airspace. Wrong; it's class C. The airport and runway were in sight but everything felt low and I realized I was going through 1;400 ft AGL so I leveled; slowed and configured and continued to imobe using the pdi in VNAV. (All we ever heard from ATC was cleared to land and afterward cleared to the hangar.)

Original NASA ASRS Text

Title: An Air Carrier First Officer reported feeling low on approach about 15 NM from AMA and realized he was 1;400 FT AGL so he leveled; slowed and configured for landing. ATC was silent.

Narrative: At 5;000 FT MSL roughly 15 nm SE Runway 31 at AMA we accepted a visual via direct IMOBE then Runway 31. We don't have a RNAV 31 chart but it's in the database. We had previously been given direct from FUZ to AMA and that put us just a little east of the final for 31. We flew to IMOBE in LNAV and I selected 4;200 FT in the MCP and started to descend via V/S. I was tired and just assumed we were in Class B airspace. Wrong; it's Class C. The Airport and Runway were in sight but everything felt low and I realized I was going through 1;400 FT AGL so I leveled; slowed and configured and continued to IMOBE using the PDI in VNAV. (All we ever heard from ATC was cleared to land and afterward cleared to the hangar.)

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	1040748
Time
Date	201210
Local Time Of Day	1201-1800
Place
Locale Reference	AMA.Airport
State Reference	TX
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Person 1
Function	First Officer Pilot Flying
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy Inflight Event / Encounter CFTT / CFIT

An air carrier first officer reported feeling low on approach about 15 NM from ama and realized he was 1;400 ft AGL so he leveled; slowed and configured for landing. ATC was silent.