Air carrier flight crew fails to comprehend subtle change to routing on pre departure clearance.

Attributes
ACN	794019
Time
Date	200807
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : clt.airport
State Reference	NC
Altitude	msl single value : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ztl.tracon tower : lga.tower
Operator	common carrier : air carrier
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 210 flight time total : 12500 flight time type : 3500
ASRS Report	794019
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
ASRS Report	793459
Events
Anomaly	non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

The error occurred due to a basic mis-reading of our pre departure clearance clearance at the gate. Pre departure clearance was as follows: **** revised segment****-BOB1 zaver ZZZ-**** filed clearance ****clt-BOB1-zaver-*** ZZZ. All too often the revised segment is exactly the same as the filed segment. We both felt this was the case. Our filed segment was actually BOB1 zaver vxv ZZZ. If under 'filed clearance' this was spelled out we would have easily seen the difference in clearances and made the appropriate adjustments. It was curious that nothing was brought to our attention until at least two hours into the flight (well beyond vxv) in a message from dispatch. It would be helpful if the revised segment portion of the pre departure clearance was only used when there actually is a revised segment. Also; the difference between clearances could be notated more clearly.

Original NASA ASRS Text

Title: ACR FLT CREW FAILS TO COMPREHEND SUBTLE CHANGE TO ROUTING ON PDC.

Narrative: THE ERROR OCCURRED DUE TO A BASIC MIS-READING OF OUR PDC CLEARANCE AT THE GATE. PDC WAS AS FOLLOWS: **** REVISED SEGMENT****-BOB1 ZAVER ZZZ-**** FILED CLEARANCE ****CLT-BOB1-ZAVER-*** ZZZ. ALL TOO OFTEN THE REVISED SEGMENT IS EXACTLY THE SAME AS THE FILED SEGMENT. WE BOTH FELT THIS WAS THE CASE. OUR FILED SEGMENT WAS ACTUALLY BOB1 ZAVER VXV ZZZ. IF UNDER 'FILED CLEARANCE' THIS WAS SPELLED OUT WE WOULD HAVE EASILY SEEN THE DIFFERENCE IN CLEARANCES AND MADE THE APPROPRIATE ADJUSTMENTS. IT WAS CURIOUS THAT NOTHING WAS BROUGHT TO OUR ATTENTION UNTIL AT LEAST TWO HOURS INTO THE FLT (WELL BEYOND VXV) IN A MESSAGE FROM DISPATCH. IT WOULD BE HELPFUL IF THE REVISED SEGMENT PORTION OF THE PDC WAS ONLY USED WHEN THERE ACTUALLY IS A REVISED SEGMENT. ALSO; THE DIFFERENCE BETWEEN CLEARANCES COULD BE NOTATED MORE CLEARLY.

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.