<< >> NASA ASRS Report 368450, May 1997

Medium large transport aircraft cleared to cross an intersection at assigned altitude. Due to cumulo nimbus buildup over the intersection, reporter captain diverted around it and didn't descend to assigned altitude. Due to frequency congestion, reporter was unable to notify ATC of the deviation.

Attributes
ACN	368450
Time
Date	199705
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dvv
State Reference	CO
Altitude	msl bound lower : 20000 msl bound upper : 21000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other arrival star : star
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 200 flight time total : 13000 flight time type : 4000
ASRS Report	368450
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : crossing restriction not met inflight encounter : weather non adherence : clearance other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation other

Narrative:

ZDV cleared us to cross ramms intersection at FL200 at 280 KTS. As we approached the intersection it became obvious a cell was building rapidly at ramms intersection. FL200 would have put us into the tops so we asked for altitude relief. Frequency congestion and controller saturation caused us to cross about 2 mi abeam ramms intersection at FL210. We were given over to den approach and no comment was made by them. Had I complied with the FL200 crossing restr, flight attendants would have been injured. I need to coordinate earlier with ATC to avoid this problem.

Related reports:

• An air carrier MD80 flight crew was given a crossing altitud...

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Original NASA ASRS Text

Title: MLG ACFT CLRED TO CROSS AN INTXN AT ASSIGNED ALT. DUE TO CUMULO NIMBUS BUILDUP OVER THE INTXN, RPTR CAPT DIVERTED AROUND IT AND DIDN'T DSND TO ASSIGNED ALT. DUE TO FREQ CONGESTION, RPTR WAS UNABLE TO NOTIFY ATC OF THE DEV.

Narrative: ZDV CLRED US TO CROSS RAMMS INTXN AT FL200 AT 280 KTS. AS WE APCHED THE INTXN IT BECAME OBVIOUS A CELL WAS BUILDING RAPIDLY AT RAMMS INTXN. FL200 WOULD HAVE PUT US INTO THE TOPS SO WE ASKED FOR ALT RELIEF. FREQ CONGESTION AND CTLR SATURATION CAUSED US TO CROSS ABOUT 2 MI ABEAM RAMMS INTXN AT FL210. WE WERE GIVEN OVER TO DEN APCH AND NO COMMENT WAS MADE BY THEM. HAD I COMPLIED WITH THE FL200 XING RESTR, FLT ATTENDANTS WOULD HAVE BEEN INJURED. I NEED TO COORDINATE EARLIER WITH ATC TO AVOID THIS PROB.

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.