B737 landing phl given last min visual approach clearance change, begins descent prior to clearance.

Attributes
ACN	604206
Time
Date	200312
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : mxe.vor
State Reference	PA
Altitude	msl single value : 3000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : phl.tracon tracon : nct.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	descent : approach
Route In Use	approach : visual arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : phl.tracon
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent : approach
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 18000 flight time type : 2500
ASRS Report	604026
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 190 flight time total : 15000 flight time type : 600
ASRS Report	603780
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera
Resolutory Action	flight crew : returned to assigned altitude flight crew : returned to original clearance
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Checked in with phl approach control and was told to expect visual to runway 27R. We were on vectors for that approach when ATC said to intercept the liberty visual for runway 27L. It turns out that we were already on the mxe 108 degree radial and we did not have time to adequately brief and review the 'liberty' procedure. We were asked by ATC if we had the traffic lined up on runway 27R and we replied 'negative.' it was at this point that I began to review the liberty procedure and approach plate. It states that you must be at or above 3000 ft at 33 DME and at or below 2100 ft at 27 DME. We were at 31 DME at this point, so I started down to make 2100 ft or below by 27 DME. Going through 2700 ft, the first officer asked ATC if we were cleared for the approach and he responded 'negative, maintain 3000 ft, do you have the runway 27R traffic in sight?' we quickly returned to 3000 ft and called the traffic in sight. We were then cleared for the approach. We crossed the 27 DME at 2800 ft instead of the 2100 ft or below. We continued the approach to landing uneventfully, maintaining visual contact with the traffic on runway 27R final approach. A lot of confusion could have been prevented with more heads up notice of the 'liberty visual' clearance. We were cleared to intercept without the benefit of reviewing the approach plate.

Original NASA ASRS Text

Title: B737 LNDG PHL GIVEN LAST MIN VISUAL APCH CLRNC CHANGE, BEGINS DSCNT PRIOR TO CLRNC.

Narrative: CHKED IN WITH PHL APCH CTL AND WAS TOLD TO EXPECT VISUAL TO RWY 27R. WE WERE ON VECTORS FOR THAT APCH WHEN ATC SAID TO INTERCEPT THE LIBERTY VISUAL FOR RWY 27L. IT TURNS OUT THAT WE WERE ALREADY ON THE MXE 108 DEG RADIAL AND WE DID NOT HAVE TIME TO ADEQUATELY BRIEF AND REVIEW THE 'LIBERTY' PROC. WE WERE ASKED BY ATC IF WE HAD THE TFC LINED UP ON RWY 27R AND WE REPLIED 'NEGATIVE.' IT WAS AT THIS POINT THAT I BEGAN TO REVIEW THE LIBERTY PROC AND APCH PLATE. IT STATES THAT YOU MUST BE AT OR ABOVE 3000 FT AT 33 DME AND AT OR BELOW 2100 FT AT 27 DME. WE WERE AT 31 DME AT THIS POINT, SO I STARTED DOWN TO MAKE 2100 FT OR BELOW BY 27 DME. GOING THROUGH 2700 FT, THE FO ASKED ATC IF WE WERE CLRED FOR THE APCH AND HE RESPONDED 'NEGATIVE, MAINTAIN 3000 FT, DO YOU HAVE THE RWY 27R TFC IN SIGHT?' WE QUICKLY RETURNED TO 3000 FT AND CALLED THE TFC IN SIGHT. WE WERE THEN CLRED FOR THE APCH. WE CROSSED THE 27 DME AT 2800 FT INSTEAD OF THE 2100 FT OR BELOW. WE CONTINUED THE APCH TO LNDG UNEVENTFULLY, MAINTAINING VISUAL CONTACT WITH THE TFC ON RWY 27R FINAL APCH. A LOT OF CONFUSION COULD HAVE BEEN PREVENTED WITH MORE HEADS UP NOTICE OF THE 'LIBERTY VISUAL' CLRNC. WE WERE CLRED TO INTERCEPT WITHOUT THE BENEFIT OF REVIEWING THE APCH PLATE.

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.