A heavy B747-400 flight crew departing ord needed a higher speed than the 250 KTS charted on climbou...

Narrative:

Departing 28 on runway heading; after 800 ft given a right heading 120 degrees to 040. Aircraft heavy; and we have the high speed/unable ord 8 restrictions as per SOP from clearance delivery. Max performance of aircraft; in addition to thermals is making our V min (stall tape) uncomfortably close to our normal departure speed of approximately 280 KTS. I elect to speed intervene whilst we work the SID; and after we level off with still a rough ride at 5000 ft; ATC queries why we're going so fast. I tell him that we're heavy; and he wants us to slow down to 250 KTS. I explain that we have operational restrictions that we need for weight; but I did speed up without telling him by 20 KTS. In anticipation of a continuance to climb; as I'll still need the extra speed buffer until I'm through at least 8;000 ft. I was quite rushed with the turn; and the subsequent level off; plus an intermittent TCAS VFR beneath the TCA. I politely tried explaining the procedure for our hi-speed heavy weight departures out of ord in the 747; but he seemed to want us to ask for this. Either clearance delivery didn't pass along the exemption; or he perhaps was new. Nevertheless; I should have informed him of my slight operational speed need for a few minutes; will be more aggressive in the future.

Original NASA ASRS Text

Title: A heavy B747-400 flight crew departing ORD needed a higher speed than the 250 KTS charted on climbout. They had cleared the speed with Clearance Delivery; but TRACON knew nothing about it and questioned their speed.

Narrative: Departing 28 on runway heading; after 800 FT given a right heading 120 degrees to 040. Aircraft heavy; and we have the high speed/unable ORD 8 restrictions as per SOP from Clearance Delivery. Max performance of aircraft; in addition to thermals is making our V MIN (stall tape) uncomfortably close to our normal departure speed of approximately 280 KTS. I elect to speed intervene whilst we work the SID; and after we level off with still a rough ride at 5000 FT; ATC queries why we're going so fast. I tell him that we're heavy; and he wants us to slow down to 250 KTS. I explain that we have operational restrictions that we need for weight; but I did speed up without telling him by 20 KTS. In anticipation of a continuance to climb; as I'll still need the extra speed buffer until I'm through at least 8;000 FT. I was quite rushed with the turn; and the subsequent level off; plus an intermittent TCAS VFR beneath the TCA. I politely tried explaining the procedure for our hi-speed heavy weight departures out of ORD in the 747; but he seemed to want us to ask for this. Either Clearance Delivery didn't pass along the exemption; or he perhaps was new. Nevertheless; I should have informed him of my slight operational speed need for a few minutes; will be more aggressive in the future.

Data retrieved from NASA's ASRS site as of April 2012 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	834109
Time
Date	200905
Local Time Of Day	0601-1200
Place
Locale Reference	C90.TRACON
State Reference	IL
Aircraft 1
Make Model Name	B747-400
Operating Under FAR Part	Part 121
Flight Phase	Climb
Person 1
Function	Captain Pilot Flying
Experience	Flight Crew Last 90 Days 60 Flight Crew Total 18000 Flight Crew Type 5000
Person 2
Function	Pilot Not Flying First Officer
Experience	Flight Crew Last 90 Days 240 Flight Crew Total 17000 Flight Crew Type 500
Events
Anomaly	Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Speed All Types

A heavy B747-400 flight crew departing ord needed a higher speed than the 250 KTS charted on climbout. They had cleared the speed with clearance delivery; but TRACON knew nothing about it and questioned their speed.