Loss of separation occurred when fgt climbed through assigned altitude.

Attributes
ACN	124580
Time
Date	198910
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dsm
State Reference	IA
Altitude	msl bound lower : 25000 msl bound upper : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	other
Make Model Name	Fighter
Flight Phase	cruise other
Route In Use	departure other
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Fighter
Flight Phase	climbout : intermediate altitude
Route In Use	departure other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 2 controller radar : 5
ASRS Report	124580
Person 2
Affiliation	government : military
Function	flight crew : single pilot
Qualification	pilot : military
Events
Anomaly	non adherence : published procedure non adherence : required legal separation other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Miss Distance	horizontal : 21000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Fgt X departed dsm a few minutes before fgt Y. Fgt X was requesting FL250. Fgt Y was requesting FL290 same route. Fgt X was cleared to FL230, which is the vertical limit of otm lo sector. The high altitude sector reclred the aircraft to FL250 after handoff. Fgt Y flight was cleared to FL230 originally, then reclred to FL220 when fgt X slowed down and climbed very slowly out of FL230. When fgt X finally cleared FL240 climbing to FL250, I cleared fgt Y flight to FL230 and issued instructions to contact chicago center on UHF frequency 385.6. Because of poor quality UHF and our own background noise, I could not hear the readback. I immediately called on the high altitude sector to check on fgt Y altitude. That controller reported that fgt Y never called on. The aircraft was observed to climb through FL230 all the way to FL280. In the climb, it approached fgt X from behind approximately 3-4 mi, with neither myself nor the high altitude sector controller able to contact the aircraft. The aircraft reported back to my frequency approximately 30 mi later at FL280 requesting higher. The pilot said he had been unable to contact the next controller. Poor communication is obviously the major factor in this incident.

Original NASA ASRS Text

Title: LOSS OF SEPARATION OCCURRED WHEN FGT CLIMBED THROUGH ASSIGNED ALT.

Narrative: FGT X DEPARTED DSM A FEW MINUTES BEFORE FGT Y. FGT X WAS REQUESTING FL250. FGT Y WAS REQUESTING FL290 SAME ROUTE. FGT X WAS CLRED TO FL230, WHICH IS THE VERTICAL LIMIT OF OTM LO SECTOR. THE HIGH ALT SECTOR RECLRED THE ACFT TO FL250 AFTER HANDOFF. FGT Y FLT WAS CLRED TO FL230 ORIGINALLY, THEN RECLRED TO FL220 WHEN FGT X SLOWED DOWN AND CLIMBED VERY SLOWLY OUT OF FL230. WHEN FGT X FINALLY CLRED FL240 CLIMBING TO FL250, I CLRED FGT Y FLT TO FL230 AND ISSUED INSTRUCTIONS TO CONTACT CHICAGO CENTER ON UHF FREQ 385.6. BECAUSE OF POOR QUALITY UHF AND OUR OWN BACKGROUND NOISE, I COULD NOT HEAR THE READBACK. I IMMEDIATELY CALLED ON THE HIGH ALT SECTOR TO CHECK ON FGT Y ALT. THAT CTLR REPORTED THAT FGT Y NEVER CALLED ON. THE ACFT WAS OBSERVED TO CLIMB THROUGH FL230 ALL THE WAY TO FL280. IN THE CLIMB, IT APCHED FGT X FROM BEHIND APPROX 3-4 MI, WITH NEITHER MYSELF NOR THE HIGH ALT SECTOR CTLR ABLE TO CONTACT THE ACFT. THE ACFT REPORTED BACK TO MY FREQ APPROX 30 MI LATER AT FL280 REQUESTING HIGHER. THE PLT SAID HE HAD BEEN UNABLE TO CONTACT THE NEXT CTLR. POOR COM IS OBVIOUSLY THE MAJOR FACTOR IN THIS INCIDENT.

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.