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While flying a non-precision back course approach; a C525 citation pilot received a low altitude alert and an egpws 'terrain' warning when he misread the altitude at the first step down fix and instead descended to the lower altitude published for a subsequent fix.
| Attributes | |
| ACN | 873637 |
| Time | |
| Date | 201002 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | LUK.Airport |
| State Reference | OH |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | Citationjet (C525/C526) - CJ I / II / III / IV |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Final Approach |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Altitude Hold/Capture |
| Person 1 | |
| Function | Captain Single Pilot |
| Qualification | Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Multiengine |
| Experience | Flight Crew Last 90 Days 120 Flight Crew Total 10000 Flight Crew Type 2400 |
| Events | |
| Anomaly | Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT |
| Miss Distance | Vertical 400 |
Narrative:
On the back course approach to runway 3 at luk I received a low altitude alert from tower and an egpws terrain alert. Performed a missed approach. I had inadvertently descended below the MDA because I read the DME incorrectly. There are 2 step down fixes on the approach; one is at 9.6 and the other is at 4.6. I misread the 9.6 for a 4.6. A contributing factor was that I had a slight head cold which worsened during the flight.localizer based back course approaches cannot be flown utilizing FMS construction which prevents the use of VNAV coupled vertical descents. They require basically 'dive and drive' measures from the pilot. If they provided any other type of non-precision approach (GPS; NDB; etc.) to runway 3; navigation/VNAV coupling would be possible and glide paths could be displayed and captured. Localizer type approaches without GS are thus more difficult and it seems manufacturers may have some type of regulation which prevents them from allowing pilots to couple vertical modes. This is unfortunate as the pilot must compute required descent rates when the FMS is fully capable and could be flown with VNAV.
Original NASA ASRS Text
Title: While flying a non-precision back course approach; a C525 Citation Pilot received a Low Altitude Alert and an EGPWS 'Terrain' warning when he misread the altitude at the first step down fix and instead descended to the lower altitude published for a subsequent fix.
Narrative: On the Back Course approach to Runway 3 at LUK I received a Low Altitude Alert from Tower and an EGPWS terrain alert. Performed a Missed Approach. I had inadvertently descended below the MDA because I read the DME incorrectly. There are 2 step down fixes on the approach; one is at 9.6 and the other is at 4.6. I misread the 9.6 for a 4.6. A contributing factor was that I had a slight head cold which worsened during the flight.LOC based back course approaches cannot be flown utilizing FMS construction which prevents the use of VNAV coupled vertical descents. They require basically 'dive and drive' measures from the pilot. If they provided any other type of non-precision approach (GPS; NDB; etc.) to Runway 3; NAV/VNAV coupling would be possible and glide paths could be displayed and captured. Localizer type approaches without GS are thus more difficult and it seems manufacturers may have some type of regulation which prevents them from allowing pilots to couple vertical modes. This is unfortunate as the pilot must compute required descent rates when the FMS is fully capable and could be flown with VNAV.
Data retrieved from NASA's ASRS site as of April 2012 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.