An air carrier large transport pilot complains about the lda 12L approach at stl combined with TCASI...

Attributes
ACN	247186
Time
Date	199307
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : stl
State Reference	MO
Altitude	agl bound lower : 600 agl bound upper : 3000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : stl
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent : approach
Route In Use	approach : straight in
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 170 flight time total : 13500 flight time type : 5000
ASRS Report	247186
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	other
Consequence	Other
Miss Distance	horizontal : 5000
Supplementary
Primary Problem	Airport
Air Traffic Incident	other

Narrative:

This report is to point out a potentially dangerous procedure rather than a particular incident. I have experienced the same situation on several occasions at stl flying this approach (12L lda). Due to the close proximity of traffic flying simultaneous 12L-lda and 12R-ILS approachs, it is very common to experience TCASII alerts and RA's even when staying left of the 12L lda course. I feel that this margin for error is reduced to an unacceptable level and a marginal to dangerous situation exists.

Original NASA ASRS Text

Title: AN ACR LGT PLT COMPLAINS ABOUT THE LDA 12L APCH AT STL COMBINED WITH TCASII COMMANDS.

Narrative: THIS RPT IS TO POINT OUT A POTENTIALLY DANGEROUS PROC RATHER THAN A PARTICULAR INCIDENT. I HAVE EXPERIENCED THE SAME SIT ON SEVERAL OCCASIONS AT STL FLYING THIS APCH (12L LDA). DUE TO THE CLOSE PROX OF TFC FLYING SIMULTANEOUS 12L-LDA AND 12R-ILS APCHS, IT IS VERY COMMON TO EXPERIENCE TCASII ALERTS AND RA'S EVEN WHEN STAYING L OF THE 12L LDA COURSE. I FEEL THAT THIS MARGIN FOR ERROR IS REDUCED TO AN UNACCEPTABLE LEVEL AND A MARGINAL TO DANGEROUS SIT EXISTS.

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.

An air carrier large transport pilot complains about the lda 12L approach at stl combined with TCASII commands.