Standard vertical altitude separation was lost between 2 aircraft climbing to assigned altitudes.

Attributes
ACN	152369
Time
Date	199007
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : rom
State Reference	CA
Altitude	msl bound lower : 33000 msl bound upper : 34500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa
Operator	general aviation : corporate
Make Model Name	Medium Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 8
ASRS Report	152369
Person 2
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	none taken : anomaly accepted
Consequence	faa : investigated
Miss Distance	vertical : 1500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

An mdt was climbing to FL370 from sts to san. An medium large transport, from oak to lax, was climbing underneath mdt. Each time mdt vacated an altitude, I assigned medium large transport an appropriate altitude below. The medium large transport pilot was obviously not happy with the step climb and indicated so on frequency. In the vicinity of rom VOR, mdt was climbing through fl 343 for FL370 at approximately 500 FPM. Medium large transport was level at FL310. I assigned medium large transport to 'climb and maintain FL330,' assuming that the mdt would continue at 500 FPM. In 36 seconds medium large transport was at FL330. I assigned that altitude. Presuming that the medium large transport would comply with aim paragraph 270D (climb at 500-1500 FPM for the last 1000' of climb). This would give the mdt appropriate time to vacate FL350, thus ensuring 2000' altitude sep. Instead, the medium large transport pilot chose to climb 2000' in 36 seconds (3 updates of ARSR radar).

Original NASA ASRS Text

Title: STANDARD VERTICAL ALT SEPARATION WAS LOST BETWEEN 2 ACFT CLIMBING TO ASSIGNED ALTS.

Narrative: AN MDT WAS CLBING TO FL370 FROM STS TO SAN. AN MLG, FROM OAK TO LAX, WAS CLBING UNDERNEATH MDT. EACH TIME MDT VACATED AN ALT, I ASSIGNED MLG AN APPROPRIATE ALT BELOW. THE MLG PLT WAS OBVIOUSLY NOT HAPPY WITH THE STEP CLB AND INDICATED SO ON FREQ. IN THE VICINITY OF ROM VOR, MDT WAS CLBING THROUGH FL 343 FOR FL370 AT APPROX 500 FPM. MLG WAS LEVEL AT FL310. I ASSIGNED MLG TO 'CLB AND MAINTAIN FL330,' ASSUMING THAT THE MDT WOULD CONTINUE AT 500 FPM. IN 36 SECS MLG WAS AT FL330. I ASSIGNED THAT ALT. PRESUMING THAT THE MLG WOULD COMPLY WITH AIM PARAGRAPH 270D (CLB AT 500-1500 FPM FOR THE LAST 1000' OF CLB). THIS WOULD GIVE THE MDT APPROPRIATE TIME TO VACATE FL350, THUS ENSURING 2000' ALT SEP. INSTEAD, THE MLG PLT CHOSE TO CLB 2000' IN 36 SECS (3 UPDATES OF ARSR RADAR).

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.