Narrative:

In cruise 40 mi from ZZZ at 6500 ft MSL; I asked my student (private; first night cross country; and unfamiliar with G1000 EFIS); to check field elevation and tpa at ZZZ. I cannot remember his response on field elevation; perhaps indicating that I wasn't really listening; as the number I wanted was tpa. He responded that pattern altitude was 1300 ft; which he later informed me was based on an incorrect addition of 200 ft instead of 1000 ft to the field elevation; rather than referring to the published tpa). Desiring to demonstrate the vertical navigation descent planning tools of the G1000 avionics; I was already on the appropriate VNAV page; and failed to check field elevation myself either with the use of the G1000 or the paper sectional chart. The VNAV profile was programmed for a descent at 600 FPM; to arrive 6 mi from the airport at 1600 ft (I intended to descend to tpa closer to the airport; to ensure that our altitude was 'padded' and to wait for the field in sight). We flew the profile exactly; and I selected taws on the mfd main map screen. On initial contact with tower; the controller instructed us to squawk a unique code; and to report 5 mi final straight-in for runway xx. He also advised of traffic in the pattern. We completed our descent and landing checklists; and I began to search for the runway (we had the beacon in sight) and the other traffic. At about 1900 ft MSL; I became concerned that we were low because I felt that I should be able to see the runway; that the traffic in the pattern appeared to be above us; that the map was 90% yellow (the color for less than 1000 ft but more than 100 ft AGL) and that the lights on the ground appeared to indicate that we were below 1000 ft. I instructed the student to climb several hundred ft and asked again what traffic pattern was; while moving to the waypoint -- airport information page. Almost immediately after the question; the tower controller issued a low altitude alert; and provided current altimeter setting. I instructed the student to climb again; and asked the controller what traffic pattern altitude was. I'm unsure if the controller heard or responded; because my student (still unconcerned) informed me at about the same time I verified the correct altimeter setting and the field elevation according to the garmin that field elevation was 1100 ft. I commanded a climb to 2100 ft until the airport and approach lighting were in sight. I felt the primary cause was that I failed to doublechk field elevation (much less check the paper chart). Contributing factors were the preoccupation with the VNAV function; failure to reference the published AFD and sectional chart; and the student's failure to properly define and identify tpa; and the failure to program and self-brief the NDB 35 (GPS overlay) approach procedure for situational awareness (I had rejected its use because the final approach course was not exactly straight-in). EFIS was a factor in that; on most of my flts to that airport; I have only an altimeter and paper chart; simplifying altitude awareness. EFIS was a positive factor in terrain warning and ease of discovering actual field elevation when the problem was defined. I recommend that the PIC first positively identify altitude and terrain information prior to descent with the actual paper charts prior to descent and/or VNAV programming. Second; that the VNAV's altitude above waypoint (therefore AGL) feature be used instead of; or to xchk; MSL altitudes for dscnts to landing. Safe completion of the flight was possible because of prior education on human factors; specifically CFIT in both mountainous and flat terrain; prompting my immediate climb command at the first doubt. Also; the controller's prompt low altitude warning was observant and helpful; and came as soon as he possibly could have realized we had gone (even slightly) lower than was normal on approach.

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Original NASA ASRS Text

Title: INSTRUCTOR AND STUDENT PLTS EXPERIENCE CFTT ON NIGHT VFR CROSS COUNTRY.

Narrative: IN CRUISE 40 MI FROM ZZZ AT 6500 FT MSL; I ASKED MY STUDENT (PVT; FIRST NIGHT XCOUNTRY; AND UNFAMILIAR WITH G1000 EFIS); TO CHK FIELD ELEVATION AND TPA AT ZZZ. I CANNOT REMEMBER HIS RESPONSE ON FIELD ELEVATION; PERHAPS INDICATING THAT I WASN'T REALLY LISTENING; AS THE NUMBER I WANTED WAS TPA. HE RESPONDED THAT PATTERN ALT WAS 1300 FT; WHICH HE LATER INFORMED ME WAS BASED ON AN INCORRECT ADDITION OF 200 FT INSTEAD OF 1000 FT TO THE FIELD ELEVATION; RATHER THAN REFERRING TO THE PUBLISHED TPA). DESIRING TO DEMONSTRATE THE VERT NAV DSCNT PLANNING TOOLS OF THE G1000 AVIONICS; I WAS ALREADY ON THE APPROPRIATE VNAV PAGE; AND FAILED TO CHK FIELD ELEVATION MYSELF EITHER WITH THE USE OF THE G1000 OR THE PAPER SECTIONAL CHART. THE VNAV PROFILE WAS PROGRAMMED FOR A DSCNT AT 600 FPM; TO ARRIVE 6 MI FROM THE ARPT AT 1600 FT (I INTENDED TO DSND TO TPA CLOSER TO THE ARPT; TO ENSURE THAT OUR ALT WAS 'PADDED' AND TO WAIT FOR THE FIELD IN SIGHT). WE FLEW THE PROFILE EXACTLY; AND I SELECTED TAWS ON THE MFD MAIN MAP SCREEN. ON INITIAL CONTACT WITH TWR; THE CTLR INSTRUCTED US TO SQUAWK A UNIQUE CODE; AND TO RPT 5 MI FINAL STRAIGHT-IN FOR RWY XX. HE ALSO ADVISED OF TFC IN THE PATTERN. WE COMPLETED OUR DSCNT AND LNDG CHKLISTS; AND I BEGAN TO SEARCH FOR THE RWY (WE HAD THE BEACON IN SIGHT) AND THE OTHER TFC. AT ABOUT 1900 FT MSL; I BECAME CONCERNED THAT WE WERE LOW BECAUSE I FELT THAT I SHOULD BE ABLE TO SEE THE RWY; THAT THE TFC IN THE PATTERN APPEARED TO BE ABOVE US; THAT THE MAP WAS 90% YELLOW (THE COLOR FOR LESS THAN 1000 FT BUT MORE THAN 100 FT AGL) AND THAT THE LIGHTS ON THE GND APPEARED TO INDICATE THAT WE WERE BELOW 1000 FT. I INSTRUCTED THE STUDENT TO CLB SEVERAL HUNDRED FT AND ASKED AGAIN WHAT TFC PATTERN WAS; WHILE MOVING TO THE WAYPOINT -- ARPT INFO PAGE. ALMOST IMMEDIATELY AFTER THE QUESTION; THE TWR CTLR ISSUED A LOW ALT ALERT; AND PROVIDED CURRENT ALTIMETER SETTING. I INSTRUCTED THE STUDENT TO CLB AGAIN; AND ASKED THE CTLR WHAT TFC PATTERN ALT WAS. I'M UNSURE IF THE CTLR HEARD OR RESPONDED; BECAUSE MY STUDENT (STILL UNCONCERNED) INFORMED ME AT ABOUT THE SAME TIME I VERIFIED THE CORRECT ALTIMETER SETTING AND THE FIELD ELEVATION ACCORDING TO THE GARMIN THAT FIELD ELEVATION WAS 1100 FT. I COMMANDED A CLB TO 2100 FT UNTIL THE ARPT AND APCH LIGHTING WERE IN SIGHT. I FELT THE PRIMARY CAUSE WAS THAT I FAILED TO DOUBLECHK FIELD ELEVATION (MUCH LESS CHK THE PAPER CHART). CONTRIBUTING FACTORS WERE THE PREOCCUPATION WITH THE VNAV FUNCTION; FAILURE TO REF THE PUBLISHED AFD AND SECTIONAL CHART; AND THE STUDENT'S FAILURE TO PROPERLY DEFINE AND IDENT TPA; AND THE FAILURE TO PROGRAM AND SELF-BRIEF THE NDB 35 (GPS OVERLAY) APCH PROC FOR SITUATIONAL AWARENESS (I HAD REJECTED ITS USE BECAUSE THE FINAL APCH COURSE WAS NOT EXACTLY STRAIGHT-IN). EFIS WAS A FACTOR IN THAT; ON MOST OF MY FLTS TO THAT ARPT; I HAVE ONLY AN ALTIMETER AND PAPER CHART; SIMPLIFYING ALT AWARENESS. EFIS WAS A POSITIVE FACTOR IN TERRAIN WARNING AND EASE OF DISCOVERING ACTUAL FIELD ELEVATION WHEN THE PROB WAS DEFINED. I RECOMMEND THAT THE PIC FIRST POSITIVELY IDENT ALT AND TERRAIN INFO PRIOR TO DSCNT WITH THE ACTUAL PAPER CHARTS PRIOR TO DSCNT AND/OR VNAV PROGRAMMING. SECOND; THAT THE VNAV'S ALT ABOVE WAYPOINT (THEREFORE AGL) FEATURE BE USED INSTEAD OF; OR TO XCHK; MSL ALTS FOR DSCNTS TO LNDG. SAFE COMPLETION OF THE FLT WAS POSSIBLE BECAUSE OF PRIOR EDUCATION ON HUMAN FACTORS; SPECIFICALLY CFIT IN BOTH MOUNTAINOUS AND FLAT TERRAIN; PROMPTING MY IMMEDIATE CLB COMMAND AT THE FIRST DOUBT. ALSO; THE CTLR'S PROMPT LOW ALT WARNING WAS OBSERVANT AND HELPFUL; AND CAME AS SOON AS HE POSSIBLY COULD HAVE REALIZED WE HAD GONE (EVEN SLIGHTLY) LOWER THAN WAS NORMAL ON APCH.

Data retrieved from NASA's ASRS site as of January 2009 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.