A lancair 4P lost cabin pressure at FL200 when a passenger window failed.

Attributes
ACN	1014629
Time
Date	201206
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Lancair IV/IVP
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	Cabin Window
Person 1
Function	Pilot Flying
Qualification	Flight Crew Instrument Flight Crew Private
Experience	Flight Crew Last 90 Days 35 Flight Crew Total 1295 Flight Crew Type 175
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

Loud bang with an instant loss of cabin pressure. Oxygen masks which were placed on the back seat were not there. Deployed speed brakes; reduced power to idle; pointed nose down until speed reached red line. Contacted ATC while descending in VFR conditions and got clearance for 11;000 ft. Entered IMC and leveled and stabilized the aircraft with lower speed at 11;000 ft. Started looking for the reason for cabin pressure drop; found that the rear window on driver side was missing. Verified that all controls were working properly. Advised controller about missing window and that everything was ok and under control. Received clearance for 9;000 ft. Continued flight to destination at 9;000 ft without window with 170 KTS IAS. Landed without any problems.

Original NASA ASRS Text

Title: A Lancair 4P lost cabin pressure at FL200 when a passenger window failed.

Narrative: Loud bang with an instant loss of cabin pressure. Oxygen masks which were placed on the back seat were not there. Deployed speed brakes; reduced power to idle; pointed nose down until speed reached red line. Contacted ATC while descending in VFR conditions and got clearance for 11;000 FT. Entered IMC and leveled and stabilized the aircraft with lower speed at 11;000 FT. Started looking for the reason for cabin pressure drop; Found that the rear window on driver side was missing. Verified that all controls were working properly. Advised Controller about missing window and that everything was OK and under control. Received clearance for 9;000 FT. Continued flight to destination at 9;000 FT without window with 170 KTS IAS. Landed without any problems.

Data retrieved from NASA's ASRS site as of July 2013 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.