Air carrier did not receive altitude clearance amendment.

Attributes
ACN	138912
Time
Date	199003
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : lin
State Reference	CA
Altitude	msl bound lower : 29000 msl bound upper : 33000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa
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 : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 250 flight time total : 14000 flight time type : 9000
ASRS Report	138912
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : overshoot other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

While climbing en route to intercept J92 southeast of oal our flight was cleared by oak ARTCC to 'climb to FL330' and 'expedite through FL290'. A number of radio xmissions were occurring between oak ARTCC and en route IFR aircraft. A few mins passed and oak ARTCC instructed our flight to 'resume normal speed.' we complied and continued our climb to our previously assigned altitude of FL330. Passing FL300 we were asked to 'confirm that we were level FL290.' we replied 'negative, climbing through 300.' if oak ARTCC ever issued our flight instructions to maintain FL290 we never received and certainly never acknowledged same. It is possible that either the controller meant to issue that as part of the 'resume normal speed' clearance and didn't, or that his transmission was blocked. The point is that controllers are not allowing time for readback of clrncs before transmitting another. As long as the system depends on radio transmission to give and receive clrncs with no backup, this situation will continue to be repeated.

Original NASA ASRS Text

Title: ACR DID NOT RECEIVE ALT CLRNC AMENDMENT.

Narrative: WHILE CLIMBING ENRTE TO INTERCEPT J92 SE OF OAL OUR FLT WAS CLRED BY OAK ARTCC TO 'CLIMB TO FL330' AND 'EXPEDITE THROUGH FL290'. A NUMBER OF RADIO XMISSIONS WERE OCCURRING BETWEEN OAK ARTCC AND ENRTE IFR ACFT. A FEW MINS PASSED AND OAK ARTCC INSTRUCTED OUR FLT TO 'RESUME NORMAL SPEED.' WE COMPLIED AND CONTINUED OUR CLIMB TO OUR PREVIOUSLY ASSIGNED ALT OF FL330. PASSING FL300 WE WERE ASKED TO 'CONFIRM THAT WE WERE LEVEL FL290.' WE REPLIED 'NEGATIVE, CLIMBING THROUGH 300.' IF OAK ARTCC EVER ISSUED OUR FLT INSTRUCTIONS TO MAINTAIN FL290 WE NEVER RECEIVED AND CERTAINLY NEVER ACKNOWLEDGED SAME. IT IS POSSIBLE THAT EITHER THE CTLR MEANT TO ISSUE THAT AS PART OF THE 'RESUME NORMAL SPEED' CLRNC AND DIDN'T, OR THAT HIS XMISSION WAS BLOCKED. THE POINT IS THAT CTLRS ARE NOT ALLOWING TIME FOR READBACK OF CLRNCS BEFORE XMITTING ANOTHER. AS LONG AS THE SYSTEM DEPENDS ON RADIO XMISSION TO GIVE AND RECEIVE CLRNCS WITH NO BACKUP, THIS SITUATION WILL CONTINUE TO BE REPEATED.

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.