Altitude deviation. Undershoot on descent. Crossing restriction not met.

Attributes
ACN	133241
Time
Date	199001
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : lrp
State Reference	PA
Altitude	msl bound lower : 11000 msl bound upper : 17000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny
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	enroute airway : zny
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 : 60 flight time total : 10000
ASRS Report	133241
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : crossing restriction not met altitude deviation : undershoot non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : insufficient time other
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

On flight air carrier xx, pit-phl at FL250, I received clearance to cross 10 mi east of lrp at 11000'. 19 mi west of lrp at 17000', I was told to level at 16000' and turn left for traffic. After questioning ATC about my clearance, he thought we were cleared to cross lrp at 11000'. We continued to receive vectors and landed at phl. While we never violated either of the above clrncs, we could not have made a 10-mi west of lrp at 11000', and that may have been the original intention of ATC. Clrncs to cross east or west are easily misunderstood. Instead the term 'before reaching' or 'after passing' are more descriptive and less prone to misinterp.

Original NASA ASRS Text

Title: ALT DEVIATION. UNDERSHOOT ON DESCENT. CROSSING RESTRICTION NOT MET.

Narrative: ON FLT ACR XX, PIT-PHL AT FL250, I RECEIVED CLRNC TO CROSS 10 MI E OF LRP AT 11000'. 19 MI W OF LRP AT 17000', I WAS TOLD TO LEVEL AT 16000' AND TURN LEFT FOR TFC. AFTER QUESTIONING ATC ABOUT MY CLRNC, HE THOUGHT WE WERE CLRED TO CROSS LRP AT 11000'. WE CONTINUED TO RECEIVE VECTORS AND LANDED AT PHL. WHILE WE NEVER VIOLATED EITHER OF THE ABOVE CLRNCS, WE COULD NOT HAVE MADE A 10-MI W OF LRP AT 11000', AND THAT MAY HAVE BEEN THE ORIGINAL INTENTION OF ATC. CLRNCS TO CROSS E OR W ARE EASILY MISUNDERSTOOD. INSTEAD THE TERM 'BEFORE REACHING' OR 'AFTER PASSING' ARE MORE DESCRIPTIVE AND LESS PRONE TO MISINTERP.

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.