<< >> NASA ASRS Report 195605, December 1991

Small aircraft twin on IFR training flight was low on GS for bfi. Approach controller advised low. Pilot had allegedly followed erroneous GS indication.

Attributes
ACN	195605
Time
Date	199112
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bfi
State Reference	WA
Altitude	msl bound lower : 1600 msl bound upper : 2200
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sea
Operator	general aviation : instructional
Make Model Name	Small Aircraft, Low Wing, 2 Eng, Retractable Gear
Flight Phase	descent : approach landing : missed approach
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot instruction : trainee
Qualification	pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 70 flight time total : 790 flight time type : 8
ASRS Report	195605
Person 2
Affiliation	Other
Function	instruction : instructor
Qualification	pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 100 flight time total : 4000 flight time type : 900
ASRS Report	195559
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot altitude deviation : crossing restriction not met non adherence : clearance non adherence : far non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	flight crew : became reoriented other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation other

Narrative:

On an IFR multi-engine training flight in IMC with light to moderate turbulence, strong crosswind component. Were cleared for the ILS 13R approach at bfi. Were established on the localizer 2-3 mi outside nolla LOM. Prior to the OM, received GS indication of descent; descended to 1600 ft on the GS and localizer as indicated. Sea approach control advised of low altitude; corrected to 2200 ft. At this point received indication of LOM passage. Recognized an apparent GS malfunction and initiated an immediate missed approach. Advised sea approach of malfunction and that we were climbing on the localizer (per published missed approach procedure). Encountered VFR conditions and requested VFR on top clearance. Received radar vectors were advised to maintain VFR. Cancelled IFR and maintained VFR to a successful landing at bfi. Conclusion: should have backed up GS indications with OM crossing altitude. This would have allowed us to recognize the malfunction earlier and therefore communicate this information to approach control sooner. Human factors: only second IFR multi-engine flight; may have been relying a little too much on instructor to point out mistakes. Because I'm a cfii, the instructor was probably relying on me not to make mistakes.

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Original NASA ASRS Text

Title: SMA TWIN ON IFR TRAINING FLT WAS LOW ON GS FOR BFI. APCH CTLR ADVISED LOW. PLT HAD ALLEGEDLY FOLLOWED ERRONEOUS GS INDICATION.

Narrative: ON AN IFR MULTI-ENG TRAINING FLT IN IMC WITH LIGHT TO MODERATE TURB, STRONG XWIND COMPONENT. WERE CLRED FOR THE ILS 13R APCH AT BFI. WERE ESTABLISHED ON THE LOC 2-3 MI OUTSIDE NOLLA LOM. PRIOR TO THE OM, RECEIVED GS INDICATION OF DSCNT; DSNDED TO 1600 FT ON THE GS AND LOC AS INDICATED. SEA APCH CTL ADVISED OF LOW ALT; CORRECTED TO 2200 FT. AT THIS POINT RECEIVED INDICATION OF LOM PASSAGE. RECOGNIZED AN APPARENT GS MALFUNCTION AND INITIATED AN IMMEDIATE MISSED APCH. ADVISED SEA APCH OF MALFUNCTION AND THAT WE WERE CLBING ON THE LOC (PER PUBLISHED MISSED APCH PROC). ENCOUNTERED VFR CONDITIONS AND REQUESTED VFR ON TOP CLRNC. RECEIVED RADAR VECTORS WERE ADVISED TO MAINTAIN VFR. CANCELLED IFR AND MAINTAINED VFR TO A SUCCESSFUL LNDG AT BFI. CONCLUSION: SHOULD HAVE BACKED UP GS INDICATIONS WITH OM XING ALT. THIS WOULD HAVE ALLOWED US TO RECOGNIZE THE MALFUNCTION EARLIER AND THEREFORE COMMUNICATE THIS INFO TO APCH CTL SOONER. HUMAN FACTORS: ONLY SECOND IFR MULTI-ENG FLT; MAY HAVE BEEN RELYING A LITTLE TOO MUCH ON INSTRUCTOR TO POINT OUT MISTAKES. BECAUSE I'M A CFII, THE INSTRUCTOR WAS PROBABLY RELYING ON ME NOT TO MAKE MISTAKES.

Data retrieved from NASA's ASRS site as of July 2007 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.