Glider pilot exceeds 'wave window' granted by ATC.

Attributes
ACN	717723
Time
Date	200611
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zoa.artcc
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa.artcc
Operator	general aviation : personal
Make Model Name	Sail Plane
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	climbout : vacating altitude
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 37 flight time total : 712 flight time type : 130
ASRS Report	717723
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	aircraft : equipment problem dissipated flight crew : exited penetrated airspace flight crew : overcame equipment problem
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

Today was a good sailplane flying day with high altitude lenticular clouds over the minden tahoe airfield in nevada. I took off and requested that the FBO telephone reno center and request that a wave window be opened above 17999 ft. Permission was granted up to a ceiling of 27000 ft in the 'west wave window.' at 24500 ft my altimeter ceased to read any further increase in altitude. I reasoned that I had reached the maximum ht of the ascending air mass. I did not detect the malfunction for some time; until I checked a backup altimeter; and discovered I had inadvertently climbed to 30050 ft. I immediately informed the FBO on 123.30. The FBO has telephone contact with reno center. I then began a controled spoiler descent to below 27000 ft. I do not know what caused the primary altimeter to cease working. It began to work again as I descended below 23000 ft. My GPS based cambridge 302 flight computer read the correct altitude; as did the becker transponder; but until I suspected that the primary altimeter had 'frozen;' I had these instruments on other settings that did not display altitude. What can be done to prevent a recurrence? Have at least 2 altimeters visible at all times; and periodically check the transponder for altitude; as backup.

Original NASA ASRS Text

Title: GLIDER PLT EXCEEDS 'WAVE WINDOW' GRANTED BY ATC.

Narrative: TODAY WAS A GOOD SAILPLANE FLYING DAY WITH HIGH ALT LENTICULAR CLOUDS OVER THE MINDEN TAHOE AIRFIELD IN NEVADA. I TOOK OFF AND REQUESTED THAT THE FBO TELEPHONE RENO CTR AND REQUEST THAT A WAVE WINDOW BE OPENED ABOVE 17999 FT. PERMISSION WAS GRANTED UP TO A CEILING OF 27000 FT IN THE 'W WAVE WINDOW.' AT 24500 FT MY ALTIMETER CEASED TO READ ANY FURTHER INCREASE IN ALT. I REASONED THAT I HAD REACHED THE MAX HT OF THE ASCENDING AIR MASS. I DID NOT DETECT THE MALFUNCTION FOR SOME TIME; UNTIL I CHKED A BACKUP ALTIMETER; AND DISCOVERED I HAD INADVERTENTLY CLBED TO 30050 FT. I IMMEDIATELY INFORMED THE FBO ON 123.30. THE FBO HAS TELEPHONE CONTACT WITH RENO CTR. I THEN BEGAN A CTLED SPOILER DSCNT TO BELOW 27000 FT. I DO NOT KNOW WHAT CAUSED THE PRIMARY ALTIMETER TO CEASE WORKING. IT BEGAN TO WORK AGAIN AS I DSNDED BELOW 23000 FT. MY GPS BASED CAMBRIDGE 302 FLT COMPUTER READ THE CORRECT ALT; AS DID THE BECKER XPONDER; BUT UNTIL I SUSPECTED THAT THE PRIMARY ALTIMETER HAD 'FROZEN;' I HAD THESE INSTS ON OTHER SETTINGS THAT DID NOT DISPLAY ALT. WHAT CAN BE DONE TO PREVENT A RECURRENCE? HAVE AT LEAST 2 ALTIMETERS VISIBLE AT ALL TIMES; AND PERIODICALLY CHK THE XPONDER FOR ALT; AS BACKUP.

Data retrieved from NASA's ASRS site as of January 2009 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.