Reporter flight may have descended below TCA while completing visual approach.

Attributes
ACN	138960
Time
Date	199003
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : srp airport : phx
State Reference	AZ
Altitude	msl bound lower : 3100 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : phx
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent : approach
Route In Use	approach : visual arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 250 flight time total : 14000 flight time type : 9000
ASRS Report	138960
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation
Situations
ATC Facility	procedure or policy : unspecified

Narrative:

Arriving at phx skyharbor airport, our flight was rdr vectored 170 degree magnetic departing the srp 312 degree radial/26 DME fix and descending to 7000' MSL for landing on runway 8R. Control was handed to the final controller who cleared our flight for the 'freeway visibility' to 8R, a published visibility approach. I descended to 3100' MSL as the published approach advises to complete base turn above 4000' MSL and cross 13 DME west at 3100 MSL. We were on base leg. Descending through 3500' MSL the final controller advised we were below the TCA. Phoenix has a new TCA and a published visibility approach which if followed will allow descent below the TCA, which is not depicted on the approach plate. The degenerating effect on safety is obvious. The TCA's are almost universally difficult to define. Many boundaries are defined by landmarks which IFR flown aircraft have little means of determining. TCA charts are carried but are 1) too small to read accurately, 2) do not adequately provide radio navigation boundaries and 3) must be interpreted by a pilot in a darkened cockpit while at the same time the same pilot is responsible to 'see and avoid' all traffic. In trying to obey the letter of the law, the purpose (traffic sep) is totally compromised.

Original NASA ASRS Text

Title: REPORTER FLT MAY HAVE DESCENDED BELOW TCA WHILE COMPLETING VISUAL APCH.

Narrative: ARRIVING AT PHX SKYHARBOR ARPT, OUR FLT WAS RDR VECTORED 170 DEG MAGNETIC DEPARTING THE SRP 312 DEG RADIAL/26 DME FIX AND DSNDING TO 7000' MSL FOR LNDG ON RWY 8R. CTL WAS HANDED TO THE FINAL CTLR WHO CLRED OUR FLT FOR THE 'FREEWAY VIS' TO 8R, A PUBLISHED VIS APCH. I DSNDED TO 3100' MSL AS THE PUBLISHED APCH ADVISES TO COMPLETE BASE TURN ABOVE 4000' MSL AND CROSS 13 DME W AT 3100 MSL. WE WERE ON BASE LEG. DSNDING THROUGH 3500' MSL THE FINAL CTLR ADVISED WE WERE BELOW THE TCA. PHOENIX HAS A NEW TCA AND A PUBLISHED VIS APCH WHICH IF FOLLOWED WILL ALLOW DSCNT BELOW THE TCA, WHICH IS NOT DEPICTED ON THE APCH PLATE. THE DEGENERATING EFFECT ON SAFETY IS OBVIOUS. THE TCA'S ARE ALMOST UNIVERSALLY DIFFICULT TO DEFINE. MANY BOUNDARIES ARE DEFINED BY LANDMARKS WHICH IFR FLOWN ACFT HAVE LITTLE MEANS OF DETERMINING. TCA CHARTS ARE CARRIED BUT ARE 1) TOO SMALL TO READ ACCURATELY, 2) DO NOT ADEQUATELY PROVIDE RADIO NAV BOUNDARIES AND 3) MUST BE INTERPRETED BY A PLT IN A DARKENED COCKPIT WHILE AT THE SAME TIME THE SAME PLT IS RESPONSIBLE TO 'SEE AND AVOID' ALL TFC. IN TRYING TO OBEY THE LETTER OF THE LAW, THE PURPOSE (TFC SEP) IS TOTALLY COMPROMISED.

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.