Air carrier X non adherence to ATC clearance excursion from assigned altitude.

Attributes
ACN	267119
Time
Date	199403
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dxo
State Reference	MI
Altitude	msl bound lower : 4000 msl bound upper : 900
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other enroute airway : dtw
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 : 1000
ASRS Report	267119
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

ZOB cleared us to descend and maintain 12000 ft on the spica 2 arrival as expected. On initial contact with dtw approach, we requested the vernr (FMS) transition. After a little hesitation we were cleared the vernr transition and selected 5000 ft on the mode control panel, the final altitude on the transition. We were later told to slow to 250 KTS. The airplane, on autoplt, began a descent on the FMS transition as it is preprogrammed to be at robbi at 5000 ft, the next constraint. Approach then inquired about our altitude and advised us to maintain 7000 ft. I think we were passing about 9000 ft at the time. The FMS transition needs an altitude constraint at the beginning. All other known FMS transitions or profile dscnts have this feature enabling selection of final altitude of the procedure when cleared. The vertical profiles preprogrammed need to match the altitudes the controllers are likely to want. They then must specifically restrict us to any other altitude necessary. If the entire procedure is only a ground track (no vertical navigation) it must boldly state 'altitudes as assigned.'

Original NASA ASRS Text

Title: ACR X NON ADHERENCE TO ATC CLRNC EXCURSION FROM ASSIGNED ALT.

Narrative: ZOB CLRED US TO DSND AND MAINTAIN 12000 FT ON THE SPICA 2 ARR AS EXPECTED. ON INITIAL CONTACT WITH DTW APCH, WE REQUESTED THE VERNR (FMS) TRANSITION. AFTER A LITTLE HESITATION WE WERE CLRED THE VERNR TRANSITION AND SELECTED 5000 FT ON THE MODE CTL PANEL, THE FINAL ALT ON THE TRANSITION. WE WERE LATER TOLD TO SLOW TO 250 KTS. THE AIRPLANE, ON AUTOPLT, BEGAN A DSCNT ON THE FMS TRANSITION AS IT IS PREPROGRAMMED TO BE AT ROBBI AT 5000 FT, THE NEXT CONSTRAINT. APCH THEN INQUIRED ABOUT OUR ALT AND ADVISED US TO MAINTAIN 7000 FT. I THINK WE WERE PASSING ABOUT 9000 FT AT THE TIME. THE FMS TRANSITION NEEDS AN ALT CONSTRAINT AT THE BEGINNING. ALL OTHER KNOWN FMS TRANSITIONS OR PROFILE DSCNTS HAVE THIS FEATURE ENABLING SELECTION OF FINAL ALT OF THE PROC WHEN CLRED. THE VERT PROFILES PREPROGRAMMED NEED TO MATCH THE ALTS THE CTLRS ARE LIKELY TO WANT. THEY THEN MUST SPECIFICALLY RESTRICT US TO ANY OTHER ALT NECESSARY. IF THE ENTIRE PROC IS ONLY A GND TRACK (NO VERT NAV) IT MUST BOLDLY STATE 'ALTS AS ASSIGNED.'

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.