<< >> NASA ASRS Report 453987, October 1999

B757 crew on arrival into sea given descent clearance to 10000 ft without reference to altitude restrs on the route.

Attributes
ACN	453987
Time
Date	199910
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	intersection : olm
State Reference	WA
Altitude	msl bound lower : 12000 msl bound upper : 14000
Environment
Flight Conditions	Mixed
Light	Dawn
Aircraft 1
Controlling Facilities	artcc : zse.artcc
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Route In Use	arrival star : olm.olm2
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 13500 flight time type : 3500
ASRS Report	453987
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : multi engine pilot : commercial
Events
Anomaly	altitude deviation : crossing restriction not met non adherence : clearance
Independent Detector	other controllera other flight crewb other other : 968
Supplementary
Problem Areas	Flight Crew Human Performance Airspace Structure ATC Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

We were descending via olm 2 from pdx to sea. Cross oma at 280 KTS and fount at 250 KTS, landing south. We crossed olm at or above 16000 ft, as stated, then began descent to cross aruad at 12000 ft. Between olm and aruad, the ATC controller cleared us to 10000 ft. The descent to 10000 ft deleted our 12000 ft at aruad. We were now descending to 10000 ft to slow at fount at 250 KTS. We crossed aruad at approximately 13500 ft +/-500 ft. The controller had asked us our altitude before aruad and after his descent clearance to 10000 ft. There is a note on the olympia 2 arrival, commercial publication, at the bottom that states: 'maintain last assigned altitude until cleared to 'descend via the olympia 2 arrival,' then comply with altitude restrs as published.' I think that this last line 'then comply with the altitude restrs as published' could be misleading. Once the controller gives you a clearance to a lower altitude without a verbal restr, then you can go down to the lower altitude.

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Original NASA ASRS Text

Title: B757 CREW ON ARR INTO SEA GIVEN DSCNT CLRNC TO 10000 FT WITHOUT REF TO ALT RESTRS ON THE RTE.

Narrative: WE WERE DSNDING VIA OLM 2 FROM PDX TO SEA. CROSS OMA AT 280 KTS AND FOUNT AT 250 KTS, LNDG S. WE CROSSED OLM AT OR ABOVE 16000 FT, AS STATED, THEN BEGAN DSCNT TO CROSS ARUAD AT 12000 FT. BTWN OLM AND ARUAD, THE ATC CTLR CLRED US TO 10000 FT. THE DSCNT TO 10000 FT DELETED OUR 12000 FT AT ARUAD. WE WERE NOW DSNDING TO 10000 FT TO SLOW AT FOUNT AT 250 KTS. WE CROSSED ARUAD AT APPROX 13500 FT +/-500 FT. THE CTLR HAD ASKED US OUR ALT BEFORE ARUAD AND AFTER HIS DSCNT CLRNC TO 10000 FT. THERE IS A NOTE ON THE OLYMPIA 2 ARR, COMMERCIAL PUB, AT THE BOTTOM THAT STATES: 'MAINTAIN LAST ASSIGNED ALT UNTIL CLRED TO 'DSND VIA THE OLYMPIA 2 ARR,' THEN COMPLY WITH ALT RESTRS AS PUBLISHED.' I THINK THAT THIS LAST LINE 'THEN COMPLY WITH THE ALT RESTRS AS PUBLISHED' COULD BE MISLEADING. ONCE THE CTLR GIVES YOU A CLRNC TO A LOWER ALT WITHOUT A VERBAL RESTR, THEN YOU CAN GO DOWN TO THE LOWER ALT.

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.