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ATR42 flight crew deviate from assigned altitude due to icing when ATC is unable to immediately provide altitude change.
| Attributes | |
| ACN | 470303 |
| Time | |
| Date | 200004 |
| Day | Wed |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | navaid : msn.vortac |
| State Reference | WI |
| Altitude | msl single value : 17000 |
| Environment | |
| Flight Conditions | IMC |
| Weather Elements | Turbulence Thunderstorm |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zau.artcc tower : mci.tower |
| Operator | common carrier : air carrier |
| Make Model Name | ATR 42 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : enroute altitude change |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 3400 flight time type : 120 |
| ASRS Report | 470303 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : multi engine pilot : instrument pilot : commercial |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter : weather inflight encounter other non adherence : clearance other spatial deviation |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : exited adverse environment flight crew : took precautionary avoidance action |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance Weather ATC Human Performance Aircraft |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
| Situations | |
| ATC Facility | staffing : zau.artcc |
Narrative:
On apr/xa/00 stl-msn at 17000 ft, we encountered severe icing and were forced to descend without an ATC clearance. A contributing factor was that our WX radar was attenuating and did not see the thunderstorm cell. We attempted to contact ZAU to ask for a lower altitude. He stated he was too 'busy' and he would get back to us. At this point we could not maintain altitude without stalling the aircraft. I then elected to descend immediately to avoid a very dangerous situation. To my knowledge no action was filed. Possibly, another contributing factor was that the center controller was working 2 frequencys on a night where he should have been working 1. Several aircraft were deviating for thunderstorm avoidance. Please be advised that this was not the controller's fault, but perhaps a lack of proper staffing. (No damage occurred to the aircraft.)
Original NASA ASRS Text
Title: ATR42 FLC DEVIATE FROM ASSIGNED ALT DUE TO ICING WHEN ATC IS UNABLE TO IMMEDIATELY PROVIDE ALT CHANGE.
Narrative: ON APR/XA/00 STL-MSN AT 17000 FT, WE ENCOUNTERED SEVERE ICING AND WERE FORCED TO DSND WITHOUT AN ATC CLRNC. A CONTRIBUTING FACTOR WAS THAT OUR WX RADAR WAS ATTENUATING AND DID NOT SEE THE TSTM CELL. WE ATTEMPTED TO CONTACT ZAU TO ASK FOR A LOWER ALT. HE STATED HE WAS TOO 'BUSY' AND HE WOULD GET BACK TO US. AT THIS POINT WE COULD NOT MAINTAIN ALT WITHOUT STALLING THE ACFT. I THEN ELECTED TO DSND IMMEDIATELY TO AVOID A VERY DANGEROUS SIT. TO MY KNOWLEDGE NO ACTION WAS FILED. POSSIBLY, ANOTHER CONTRIBUTING FACTOR WAS THAT THE CTR CTLR WAS WORKING 2 FREQS ON A NIGHT WHERE HE SHOULD HAVE BEEN WORKING 1. SEVERAL ACFT WERE DEVIATING FOR TSTM AVOIDANCE. PLEASE BE ADVISED THAT THIS WAS NOT THE CTLR'S FAULT, BUT PERHAPS A LACK OF PROPER STAFFING. (NO DAMAGE OCCURRED TO THE ACFT.)
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.