Air carrier large transport altitude deviation overshot excursion from clearance altitude.

Attributes
ACN	100094
Time
Date	198812
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : dca airport : iad
State Reference	DC
Altitude	msl bound lower : 17000 msl bound upper : 18500
Environment
Flight Conditions	Mixed
Light	Dawn
Aircraft 1
Controlling Facilities	tracon : iad tower : sgu
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 11500 flight time type : 1000
ASRS Report	100094
Person 2
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Pilot Deviation Operational Deviation

Narrative:

Washington departure cleared us to 17000' MSL. Washington departure/dulles approach then transmitted 'maintain 250.' we read back 'maintain 250' and set altitude report alert to 25000'. ATC then questioned our altitude as we climbed through 18500' and told us to maintain 17000'. We were then told to maintain 250 KTS airspeed. When given 'maintain 250,' we understood it to be altitude and read back 'maintain 250.' ATC intent was for us to maintain 250 KTS. Recommend that ATC assure that 'airspeed' is included in all airspeed restrictions and thousand ft or similar altitude reference be included in all altitude assignments.pronounced 'maintain 2-5-0.'

Original NASA ASRS Text

Title: ACR LGT ALT DEVIATION OVERSHOT EXCURSION FROM CLRNC ALT.

Narrative: WASHINGTON DEP CLRED US TO 17000' MSL. WASHINGTON DEP/DULLES APCH THEN XMITTED 'MAINTAIN 250.' WE READ BACK 'MAINTAIN 250' AND SET ALT RPT ALERT TO 25000'. ATC THEN QUESTIONED OUR ALT AS WE CLBED THROUGH 18500' AND TOLD US TO MAINTAIN 17000'. WE WERE THEN TOLD TO MAINTAIN 250 KTS AIRSPD. WHEN GIVEN 'MAINTAIN 250,' WE UNDERSTOOD IT TO BE ALT AND READ BACK 'MAINTAIN 250.' ATC INTENT WAS FOR US TO MAINTAIN 250 KTS. RECOMMEND THAT ATC ASSURE THAT 'AIRSPD' IS INCLUDED IN ALL AIRSPD RESTRICTIONS AND THOUSAND FT OR SIMILAR ALT REF BE INCLUDED IN ALL ALT ASSIGNMENTS.PRONOUNCED 'MAINTAIN 2-5-0.'

Data retrieved from NASA's ASRS site as of August 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.