Pilot of sailplane in class a descends below assigned block altitude.

Attributes
ACN	269381
Time
Date	199404
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : jli
State Reference	CA
Altitude	msl bound lower : 23000 msl bound upper : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla tracon : sdf
Operator	general aviation : personal
Make Model Name	Sail Plane
Operating Under FAR Part	Part 91
Flight Phase	cruise other cruise other other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 46 flight time total : 1627 flight time type : 650
ASRS Report	269381
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter other non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was operating a sailplane on an IFR flight plan in class a airspace with an assigned block altitude. I was unable to fly within the block altitude assigned and was not able to receive a clearance before I descended below the block altitude. I attribute my inability to properly coordinate a lower altitude in time to frequency congestion and the severity of the sinking air mass. As the pilot I needed to anticipate higher sink rates and frequency congestion. The solution is to ask for a larger block altitude based on the conditions and call with a more generous margin before coming near the bottom of the block. For the controller, it is better to put traffic above rather than below a sailplane. A sailplane can easily control ascents and will rarely have a problem breaking a maximum altitude. Dscnts are easy and can be rapid in a sailplane however sometimes they cannot be controlled. If there is a potential conflict the controller needs to resolve, the sailplane can move down easily.

Original NASA ASRS Text

Title: PLT OF SAILPLANE IN CLASS A DSNDS BELOW ASSIGNED BLOCK ALT.

Narrative: I WAS OPERATING A SAILPLANE ON AN IFR FLT PLAN IN CLASS A AIRSPACE WITH AN ASSIGNED BLOCK ALT. I WAS UNABLE TO FLY WITHIN THE BLOCK ALT ASSIGNED AND WAS NOT ABLE TO RECEIVE A CLRNC BEFORE I DSNDED BELOW THE BLOCK ALT. I ATTRIBUTE MY INABILITY TO PROPERLY COORDINATE A LOWER ALT IN TIME TO FREQ CONGESTION AND THE SEVERITY OF THE SINKING AIR MASS. AS THE PLT I NEEDED TO ANTICIPATE HIGHER SINK RATES AND FREQ CONGESTION. THE SOLUTION IS TO ASK FOR A LARGER BLOCK ALT BASED ON THE CONDITIONS AND CALL WITH A MORE GENEROUS MARGIN BEFORE COMING NEAR THE BOTTOM OF THE BLOCK. FOR THE CTLR, IT IS BETTER TO PUT TFC ABOVE RATHER THAN BELOW A SAILPLANE. A SAILPLANE CAN EASILY CTL ASCENTS AND WILL RARELY HAVE A PROB BREAKING A MAXIMUM ALT. DSCNTS ARE EASY AND CAN BE RAPID IN A SAILPLANE HOWEVER SOMETIMES THEY CANNOT BE CONTROLLED. IF THERE IS A POTENTIAL CONFLICT THE CTLR NEEDS TO RESOLVE, THE SAILPLANE CAN MOVE DOWN EASILY.

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.