BA4100 flight crew receives ambiguous clearance from ZKC ARTCC.

Attributes
ACN	443540
Time
Date	199907
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : stl.airport
State Reference	MO
Altitude	msl bound lower : 8000 msl bound upper : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc.artcc
Operator	common carrier : air carrier
Make Model Name	Jetstream 41
Operating Under FAR Part	Part 121
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 230 flight time total : 5500 flight time type : 1200
ASRS Report	443540
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 200 flight time total : 1800 flight time type : 600
ASRS Report	442496
Events
Anomaly	non adherence : published procedure non adherence : clearance other anomaly
Independent Detector	atc equipment other atc equipment : radar other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : returned to assigned airspace
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance

Narrative:

While flying en route, ZKC asked us to slow to 'minimum practical airspeed' but did not assign an airspeed. We slowed to approximately 200-210 KTS. They then issued us a vector off the arrival. A frequency change was given to us. The new controller gave us a vector to reintercept the arrival and gave us a descent to 8000 ft. We began our descent. A short time later ZKC asked what our airspeed was. We told him 243 KTS. He told us that if we were going to change airspeed we should let him know. He then assigned us 210 KTS and we slowed to this airspeed. Center should assign an airspeed to maintain if they want a specific speed, not a generic statement of 'minimum practical airspeed,' which is a highly subjective statement that varies with different phases and conditions of flight.

Original NASA ASRS Text

Title: BA4100 FLC RECEIVES AMBIGUOUS CLRNC FROM ZKC ARTCC.

Narrative: WHILE FLYING ENRTE, ZKC ASKED US TO SLOW TO 'MINIMUM PRACTICAL AIRSPD' BUT DID NOT ASSIGN AN AIRSPD. WE SLOWED TO APPROX 200-210 KTS. THEY THEN ISSUED US A VECTOR OFF THE ARR. A FREQ CHANGE WAS GIVEN TO US. THE NEW CTLR GAVE US A VECTOR TO REINTERCEPT THE ARR AND GAVE US A DSCNT TO 8000 FT. WE BEGAN OUR DSCNT. A SHORT TIME LATER ZKC ASKED WHAT OUR AIRSPD WAS. WE TOLD HIM 243 KTS. HE TOLD US THAT IF WE WERE GOING TO CHANGE AIRSPD WE SHOULD LET HIM KNOW. HE THEN ASSIGNED US 210 KTS AND WE SLOWED TO THIS AIRSPD. CTR SHOULD ASSIGN AN AIRSPD TO MAINTAIN IF THEY WANT A SPECIFIC SPD, NOT A GENERIC STATEMENT OF 'MINIMUM PRACTICAL AIRSPD,' WHICH IS A HIGHLY SUBJECTIVE STATEMENT THAT VARIES WITH DIFFERENT PHASES AND CONDITIONS OF FLT.

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.