Altitude deviation.

Attributes
ACN	148270
Time
Date	199006
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mkc
State Reference	MO
Altitude	msl bound lower : 25500 msl bound upper : 26400
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc
Operator	other
Make Model Name	Medium Large Transport
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : military
Function	flight crew : first officer
Qualification	pilot : military pilot : atp
Experience	flight time last 90 days : 75 flight time total : 2923 flight time type : 2023
ASRS Report	148270
Person 2
Affiliation	government : military
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : military
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Pilot Deviation other

Narrative:

Flying from NAS glenview, il to NAS moffett field, ca at FL260 in a navy aircraft, we inadvertently entered an area of severe thunderstorms and were in the storms for 10-15 mins. During this time we experienced severe icing, turbulence, 1/2-1' hail and lightning. The aircraft experienced altitude deviations up to 900' due to up and down drafts. ZKC noted these changes in altitude. This severe area of WX was not indicated on our radar system or prior to the flight by the WX office. Our newly installed stormscope indicated the aircraft to be on a track of about 20 degrees from any lightning points. We did receive a SIGMET warning from center which covered our flight path, but were already within the severe WX area. Once in the WX, assistance was requested from the center controller for vectors; were told he was unable. A heads-up call from the center prior to the SIGMET call would have been helpful. This incident again shows how numerous inputs can lead a flight crew into a less than safe situation.

Original NASA ASRS Text

Title: ALT DEVIATION.

Narrative: FLYING FROM NAS GLENVIEW, IL TO NAS MOFFETT FIELD, CA AT FL260 IN A NAVY ACFT, WE INADVERTENTLY ENTERED AN AREA OF SEVERE TSTMS AND WERE IN THE STORMS FOR 10-15 MINS. DURING THIS TIME WE EXPERIENCED SEVERE ICING, TURB, 1/2-1' HAIL AND LIGHTNING. THE ACFT EXPERIENCED ALT DEVIATIONS UP TO 900' DUE TO UP AND DOWN DRAFTS. ZKC NOTED THESE CHANGES IN ALT. THIS SEVERE AREA OF WX WAS NOT INDICATED ON OUR RADAR SYS OR PRIOR TO THE FLT BY THE WX OFFICE. OUR NEWLY INSTALLED STORMSCOPE INDICATED THE ACFT TO BE ON A TRACK OF ABOUT 20 DEGS FROM ANY LIGHTNING POINTS. WE DID RECEIVE A SIGMET WARNING FROM CENTER WHICH COVERED OUR FLT PATH, BUT WERE ALREADY WITHIN THE SEVERE WX AREA. ONCE IN THE WX, ASSISTANCE WAS REQUESTED FROM THE CENTER CTLR FOR VECTORS; WERE TOLD HE WAS UNABLE. A HEADS-UP CALL FROM THE CENTER PRIOR TO THE SIGMET CALL WOULD HAVE BEEN HELPFUL. THIS INCIDENT AGAIN SHOWS HOW NUMEROUS INPUTS CAN LEAD A FLT CREW INTO A LESS THAN SAFE SITUATION.

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.