Narrative:

On descent; leveling off at 10;000 feet there was a loud thunk/crack sound. The left hand windscreen was instantly spider webbed with cracks emanating from a central impact point in the lower left center; spreading to all sides of the screen. I immediately disconnected the autopilot and began to slow and level the aircraft. After resuming manual control of the aircraft; I transferred control of the aircraft to the first officer; using a positive exchange of flight controls. Once established; I donned my oxygen mask as a precautionary measure affording me both oxygen in the event of depressurization and additional physical protection for my face. I also zipped up my jacket and lowered my seat. When I had accomplished these tasks; I resumed flying the aircraft by hand; and asked the first officer to make a PA to the passengers; stating that we had sustained damage to the windscreen; there was no need to don their oxygen masks and we would be making a normal descent and landing. I then declared an emergency. I requested a lower altitude and notified them we would be slowing to a slower airspeed. They repeated the restriction of 10;000 ft and promised lower soon; speed was our discretion. During the descent the first officer and I discussed contingency plans if the screen were to fail (as it was continuing to crack); primarily focusing on the fact that he would take control of the aircraft and make the landing. We closed the curtain partially to remove the damage from passenger view and partially to provide protection to the cabin occupants in the event of total structural failure of the glass/plastic. We also notified operations; requesting they advise dispatch and notify maintenance. The remainder of the descent was conducted via normal procedures at a reduced airspeed. When we were unable to acquire the airport visually; we were climbed to 2200 ft and cleared for the ILS. We landed without further incident and taxied into parking; followed by both airport operations and fire/rescue as per their procedures (we did not request additional services upon landing). Upon closer inspection of the damage on the ground it appears as though the outer layer of the windscreen cracked; but no moisture or damage penetrated to the inner layer. No loss of pressurization occurred. No passenger injury or damage to persons/property on the ground occurred to our knowledge. No residue of a bird; nor additional damage was found during a thorough post flight of the aircraft. Due to lack of remains/residue; I suspect ice or foreign object rather than a bird.

Related reports:

Google
 

Original NASA ASRS Text

Title: When the outer pane of the Captain's windshield on their PC-12 shattered the flight crew declared an emergency and landed at their destination airport.

Narrative: On descent; leveling off at 10;000 feet there was a loud thunk/crack sound. The left hand windscreen was instantly spider webbed with cracks emanating from a central impact point in the lower left center; spreading to all sides of the screen. I immediately disconnected the autopilot and began to slow and level the aircraft. After resuming manual control of the aircraft; I transferred control of the aircraft to the First Officer; using a positive exchange of flight controls. Once established; I donned my oxygen mask as a precautionary measure affording me both oxygen in the event of depressurization and additional physical protection for my face. I also zipped up my jacket and lowered my seat. When I had accomplished these tasks; I resumed flying the aircraft by hand; and asked the First Officer to make a PA to the passengers; stating that we had sustained damage to the windscreen; there was no need to don their oxygen masks and we would be making a normal descent and landing. I then declared an emergency. I requested a lower altitude and notified them we would be slowing to a slower airspeed. They repeated the restriction of 10;000 Ft and promised lower soon; speed was our discretion. During the descent the First Officer and I discussed contingency plans if the screen were to fail (as it was continuing to crack); primarily focusing on the fact that he would take control of the aircraft and make the landing. We closed the curtain partially to remove the damage from passenger view and partially to provide protection to the cabin occupants in the event of total structural failure of the glass/plastic. We also notified operations; requesting they advise dispatch and notify maintenance. The remainder of the descent was conducted via normal procedures at a reduced airspeed. When we were unable to acquire the airport visually; we were climbed to 2200 FT and cleared for the ILS. We landed without further incident and taxied into parking; followed by both airport operations and fire/rescue as per their procedures (we did not request additional services upon landing). Upon closer inspection of the damage on the ground it appears as though the outer layer of the windscreen cracked; but no moisture or damage penetrated to the inner layer. No loss of pressurization occurred. No passenger injury or damage to persons/property on the ground occurred to our knowledge. No residue of a bird; nor additional damage was found during a thorough post flight of the aircraft. Due to lack of remains/residue; I suspect ice or foreign object rather than a bird.

Data retrieved from NASA's ASRS site as of April 2012 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.