Air carrier medium large transport flight crew fails to maintain assigned airspeed in climb.

Attributes
ACN	163840
Time
Date	199011
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : atl
State Reference	GA
Altitude	msl bound lower : 26000 msl bound upper : 30000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 5000 flight time type : 900
ASRS Report	163840
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : clearance other anomaly other anomaly other
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On climb out, captain flying, ATC asked for 310 KTS. A little above 10000' at the time, we accepted the clearance (for spacing). Since these clrncs on climb out are often given temporarily, the crew did not consider the fact that we could not sustain that speed at altitude. After at least 1 frequency change and passing through 30000', center asked us about our speed. We had reverted to a mach climb at about 26000', having forgotten that we had accepted a 310 KT clearance. The controller was upset. The captain and I should have stated that we could only accept a speed restriction temporarily. The controller who issued the clearance could have indicated how long he needed the speed restriction. Comment: pilots think in mach at altitude, controllers think in airspeed. Often controllers will want airspeed values at altitude and do not realize a 10 KT increase at 35000' is much, much different than a 10 KT increase at 10000'.

Original NASA ASRS Text

Title: ACR MLG FLT CREW FAILS TO MAINTAIN ASSIGNED AIRSPEED IN CLIMB.

Narrative: ON CLBOUT, CAPT FLYING, ATC ASKED FOR 310 KTS. A LITTLE ABOVE 10000' AT THE TIME, WE ACCEPTED THE CLRNC (FOR SPACING). SINCE THESE CLRNCS ON CLBOUT ARE OFTEN GIVEN TEMPORARILY, THE CREW DID NOT CONSIDER THE FACT THAT WE COULD NOT SUSTAIN THAT SPD AT ALT. AFTER AT LEAST 1 FREQ CHANGE AND PASSING THROUGH 30000', CENTER ASKED US ABOUT OUR SPD. WE HAD REVERTED TO A MACH CLB AT ABOUT 26000', HAVING FORGOTTEN THAT WE HAD ACCEPTED A 310 KT CLRNC. THE CTLR WAS UPSET. THE CAPT AND I SHOULD HAVE STATED THAT WE COULD ONLY ACCEPT A SPD RESTRICTION TEMPORARILY. THE CTLR WHO ISSUED THE CLRNC COULD HAVE INDICATED HOW LONG HE NEEDED THE SPD RESTRICTION. COMMENT: PLTS THINK IN MACH AT ALT, CTLRS THINK IN AIRSPD. OFTEN CTLRS WILL WANT AIRSPD VALUES AT ALT AND DO NOT REALIZE A 10 KT INCREASE AT 35000' IS MUCH, MUCH DIFFERENT THAN A 10 KT INCREASE AT 10000'.

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.