Air carrier in profile descent misses crossing restriction.

Attributes
ACN	171353
Time
Date	199102
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : yyz
State Reference	ON
Altitude	msl bound lower : 11000 msl bound upper : 13000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival : profile descent enroute airway : yyz
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 180 flight time total : 5500 flight time type : 1500
ASRS Report	171353
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : crossing restriction not met non adherence : clearance non adherence : published procedure
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flying profile descent, toronto, ont, runway 24L and 24R. Passed ywt at 15000' (restriction is to cross 'at or between 17000-13000'.' misread next restriction ('cross ywt 26 DME...'). Therefore, we crossed yyz 26 DME at approximately 13000'. This procedure needs revision for several reasons: 1) though ywt can be crossed at or between 17000-13000', any air carrier crossing at much above 13000' will have great difficulty making the next restriction, for it is only 9 mi away. Prevailing west winds only make the problem worse. 2) the other arrival gates make use of 2 VOR references in most cases, except for the yyz 26 DME crossing. 3) chart is quite cluttered, and information is not strategically located (i.e., 'yyz 26 DME' information is closer to ywt than the identify box for ywt. Easy to associate the two). 4) these procedures are rare (lax and yyz are the only 2 I know of). Clearance for them always provokes many questions (i.e., 'can we descend now?'). Recommendations: 1) delete profile dscnts. A senior supervisor of ATC in yyz said they don't like them. Neither do we. If the users don't like it, get rid of it. Stl did, and we haven't lost a thing there. If 1) not possible: 2) simplify the procedure. On each arrival routing, reference all xings to 1 VOR only (df1a1 does this well). 3) change ywt crossing to 13000'; or, better yet, change ywt crossing to 11000' at 250 KTS and delete yyz 26 DME crossing.

Original NASA ASRS Text

Title: ACR IN PROFILE DESCENT MISSES CROSSING RESTRICTION.

Narrative: FLYING PROFILE DSNT, TORONTO, ONT, RWY 24L AND 24R. PASSED YWT AT 15000' (RESTRICTION IS TO CROSS 'AT OR BTWN 17000-13000'.' MISREAD NEXT RESTRICTION ('CROSS YWT 26 DME...'). THEREFORE, WE CROSSED YYZ 26 DME AT APPROX 13000'. THIS PROC NEEDS REVISION FOR SEVERAL REASONS: 1) THOUGH YWT CAN BE CROSSED AT OR BTWN 17000-13000', ANY ACR XING AT MUCH ABOVE 13000' WILL HAVE GREAT DIFFICULTY MAKING THE NEXT RESTRICTION, FOR IT IS ONLY 9 MI AWAY. PREVAILING W WINDS ONLY MAKE THE PROB WORSE. 2) THE OTHER ARR GATES MAKE USE OF 2 VOR REFS IN MOST CASES, EXCEPT FOR THE YYZ 26 DME XING. 3) CHART IS QUITE CLUTTERED, AND INFO IS NOT STRATEGICALLY LOCATED (I.E., 'YYZ 26 DME' INFO IS CLOSER TO YWT THAN THE IDENT BOX FOR YWT. EASY TO ASSOCIATE THE TWO). 4) THESE PROCS ARE RARE (LAX AND YYZ ARE THE ONLY 2 I KNOW OF). CLRNC FOR THEM ALWAYS PROVOKES MANY QUESTIONS (I.E., 'CAN WE DSND NOW?'). RECOMMENDATIONS: 1) DELETE PROFILE DSCNTS. A SENIOR SUPVR OF ATC IN YYZ SAID THEY DON'T LIKE THEM. NEITHER DO WE. IF THE USERS DON'T LIKE IT, GET RID OF IT. STL DID, AND WE HAVEN'T LOST A THING THERE. IF 1) NOT POSSIBLE: 2) SIMPLIFY THE PROC. ON EACH ARR RTING, REF ALL XINGS TO 1 VOR ONLY (DF1A1 DOES THIS WELL). 3) CHANGE YWT XING TO 13000'; OR, BETTER YET, CHANGE YWT XING TO 11000' AT 250 KTS AND DELETE YYZ 26 DME XING.

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.