An LNAV approach plate minimum altitude formatting caused a C172 pilot to use the lpv decision altit...

Attributes
ACN	807488
Time
Date	200809
Local Time Of Day	1801 To 2400
Place
State Reference	WA
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	approach : instrument non precision
Flight Plan	IFR
Person 1
Affiliation	other
Function	instruction : trainee
Qualification	pilot : private
Experience	flight time last 90 days : 35 flight time total : 120 flight time type : 120
ASRS Report	807488
Events
Anomaly	altitude deviation : crossing restriction not met non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	aircraft equipment : gpws other flight crewa
Resolutory Action	none taken : detected after the fact
Supplementary
Problem Areas	Chart Or Publication
Primary Problem	Chart Or Publication
Situations
Chart	approach : lnav

Narrative:

Description: while shooting LNAV approach; used lpv decision altitude instead of LNAV MDA. Detailed description: while shooting LNAV (GPS) approach; looked at the commercial approach plate and got confused with the lpv decision altitude while approach briefing. Used the lpv decision altitude instead of LNAV MDA as the former appears in the briefing area of the approach plate. Also lpv and LNAV are resembling. This is compounded by the fact that it was night with dim cockpit light and low pilot experience. This could have been fatal as lpv decision altitude is 763 ft and LNAV MDA is 1600 ft. Possible cause: 1) low experience; 2) pilot stress; 3) pilot oversight. Discovery of the problem: 1) instructor found the issue and correction was made. 2) onboard GPS also gave the low terrain warning. Suggestion corrective actions: 1) IFR flight training should place emphasis on reviewing approach plates mandatory before flight; like WX review. 2) commercial approach plates must not list da(H)/MDA(H) in the briefing strip at the top. This is the style followed by govt charts. Inexperienced pilots/stressed pilots may look at the number in briefing strip and use it rather than looking down for the details. Possible error scenarios: 1) using ILS decision altitude instead of localizer MDA. 2) using lpv decision altitude instead of LNAV MDA. 3) using straight-in minimums instead of circling minimums.

Original NASA ASRS Text

Title: AN LNAV APCH PLATE MINIMUM ALT FORMATTING CAUSED A C172 PLT TO USE THE LPV DECISION ALT VERSUS THE LNAV MDA NEARLY CAUSING A CFTT EVENT.

Narrative: DESCRIPTION: WHILE SHOOTING LNAV APCH; USED LPV DECISION ALT INSTEAD OF LNAV MDA. DETAILED DESCRIPTION: WHILE SHOOTING LNAV (GPS) APCH; LOOKED AT THE COMMERCIAL APCH PLATE AND GOT CONFUSED WITH THE LPV DECISION ALT WHILE APCH BRIEFING. USED THE LPV DECISION ALT INSTEAD OF LNAV MDA AS THE FORMER APPEARS IN THE BRIEFING AREA OF THE APCH PLATE. ALSO LPV AND LNAV ARE RESEMBLING. THIS IS COMPOUNDED BY THE FACT THAT IT WAS NIGHT WITH DIM COCKPIT LIGHT AND LOW PLT EXPERIENCE. THIS COULD HAVE BEEN FATAL AS LPV DECISION ALT IS 763 FT AND LNAV MDA IS 1600 FT. POSSIBLE CAUSE: 1) LOW EXPERIENCE; 2) PLT STRESS; 3) PLT OVERSIGHT. DISCOVERY OF THE PROB: 1) INSTRUCTOR FOUND THE ISSUE AND CORRECTION WAS MADE. 2) ONBOARD GPS ALSO GAVE THE LOW TERRAIN WARNING. SUGGESTION CORRECTIVE ACTIONS: 1) IFR FLT TRAINING SHOULD PLACE EMPHASIS ON REVIEWING APCH PLATES MANDATORY BEFORE FLT; LIKE WX REVIEW. 2) COMMERCIAL APCH PLATES MUST NOT LIST DA(H)/MDA(H) IN THE BRIEFING STRIP AT THE TOP. THIS IS THE STYLE FOLLOWED BY GOVT CHARTS. INEXPERIENCED PLTS/STRESSED PLTS MAY LOOK AT THE NUMBER IN BRIEFING STRIP AND USE IT RATHER THAN LOOKING DOWN FOR THE DETAILS. POSSIBLE ERROR SCENARIOS: 1) USING ILS DECISION ALT INSTEAD OF LOC MDA. 2) USING LPV DECISION ALT INSTEAD OF LNAV MDA. 3) USING STRAIGHT-IN MINIMUMS INSTEAD OF CIRCLING MINIMUMS.

Data retrieved from NASA's ASRS site as of May 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.

An LNAV approach plate minimum altitude formatting caused a C172 pilot to use the lpv decision altitude versus the LNAV MDA nearly causing a cftt event.