PA28 instructor reports descending early during a VOR approach due to misreading the garmin 430 disp...

Attributes
ACN	972869
Time
Date	201109
Local Time Of Day	1201-1800
Place
Locale Reference	BUF.TRACON
State Reference	NY
Aircraft 1
Make Model Name	PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Instructor
Qualification	Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Instrument
Experience	Flight Crew Last 90 Days 50 Flight Crew Total 9300 Flight Crew Type 100
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Narrative:

While using garmin 430 GPS in lieu of DME to determine distance ( 10 DME ring ) from VOR I misread the displayed information. Displayed distance was from the final step down fix not from the VOR. This resulted in starting the descent 2-3 miles early. Conditions were VMC in flat; familiar terrain so no CFIT related hazard occurred. This is the type of error which may lead to a CFIT accident. Review; verification; and briefing of current displayed information by instructor and student would help to minimize this type of error. Instructors should treat students as required crew members and conduct pre approach briefings as such. This would not only reduce these types of mistakes but would also prepare/train the student for duties as a member of a two person flight crew. Complete knowledge and understanding of GPS navigation equipment function is also a must. Use caution when substituting GPS distance for DME information. As always; situational awareness is a must.

Original NASA ASRS Text

Title: PA28 Instructor reports descending early during a VOR approach due to misreading the Garmin 430 display. The incident occurred in VMC during an instructional flight.

Narrative: While using Garmin 430 GPS in lieu of DME to determine distance ( 10 DME ring ) from VOR I misread the displayed information. Displayed distance was from the final step down fix NOT from the VOR. This resulted in starting the descent 2-3 miles early. Conditions were VMC in flat; familiar terrain so no CFIT related hazard occurred. This is the type of error which may lead to a CFIT accident. Review; verification; and briefing of current displayed information by instructor AND student would help to minimize this type of error. Instructors should treat students as required crew members and conduct pre approach briefings as such. This would not only reduce these types of mistakes but would also prepare/train the student for duties as a member of a two person flight crew. Complete knowledge and understanding of GPS navigation equipment function is also a must. Use caution when substituting GPS distance for DME information. As always; situational awareness is a must.

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.

PA28 instructor reports descending early during a VOR approach due to misreading the garmin 430 display. The incident occurred in VMC during an instructional flight.