An ARTCC controller expressed consternation at the failures of some flight crews to fail to maintain...

Narrative:

Re the bullz RNAV STAR into ord. If an aircraft is cleared to descend via the bullz arrival that aircraft will descend and reduce speed at specified points of the arrival. The bullz has aircraft cross teddy intersection at 11;000 feet at 250 knots.both aircraft in this report were assigned 300 knots. Both aircraft were cleared direct teddy intersection. Both aircraft were issued a descent clearance to 15;000 feet. Both aircraft were then cleared to cross teddy at 11;000 feet. Both aircraft reduced speed to 250 knots at teddy without clearance to do so.I recommend speed restrictions be removed from the published bullz arrival. 70% of the time ord is on a westerly flow and approach control requires the aircraft on the bullz arrival to cross teddy at 300 knots. This often causes confusion for the pilots and sometimes results in an aircraft not performing as directed or expected. Constantly having to restate or clarify clearances causes an increase in complexity and a decrease in safety and efficiency.

Original NASA ASRS Text

Title: An ARTCC Controller expressed consternation at the failures of some flight crews to fail to maintain their assigned airspeed of 300 knots at TEDDY waypoint on the BULLZ RNAV STAR; instead slowing to 250 knots as published on the arrival.

Narrative: RE the BULLZ RNAV STAR into ORD. If an aircraft is cleared to descend via the BULLZ arrival that aircraft will descend and reduce speed at specified points of the arrival. The BULLZ has aircraft cross TEDDY intersection at 11;000 feet at 250 knots.Both aircraft in this report were assigned 300 knots. Both aircraft were cleared direct TEDDY intersection. Both aircraft were issued a descent clearance to 15;000 feet. Both aircraft were then cleared to cross TEDDY at 11;000 feet. Both aircraft reduced speed to 250 knots at TEDDY without clearance to do so.I recommend speed restrictions be removed from the published BULLZ arrival. 70% of the time ORD is on a westerly flow and Approach Control requires the aircraft on the BULLZ arrival to cross TEDDY at 300 knots. This often causes confusion for the pilots and sometimes results in an aircraft not performing as directed or expected. Constantly having to restate or clarify clearances causes an increase in complexity and a decrease in safety and efficiency.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1128825
Time
Date	201311
Local Time Of Day	1201-1800
Place
Locale Reference	ZAU.ARTCC
State Reference	IL
Aircraft 1
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR BULLZ
Flight Plan	IFR
Aircraft 2
Make Model Name	EMB ERJ 145 ER/LR
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Speed All Types

An ARTCC controller expressed consternation at the failures of some flight crews to fail to maintain their assigned airspeed of 300 knots at teddy waypoint on the bullz RNAV STAR; instead slowing to 250 knots as published on the arrival.