I have based my Mooney and flown out of KPAO for 30 years, arrived at the airport minutes after the accident and having spoke to an eye witness, have some perspective on this sad tragedy. First, my thoughts and prayers are with the family and loved ones during this terrible time. Secondly, I offer these thoughts hoping to influence a positive outcome from the tragedy.
I hope the NTSB and FAA consider the roll of the deteriorating runway in the accident chain of events. Runway 13 approach end is generously considered a washboard due to the uneven pavement, it has been unsafe for years. The Runway 31 approach end (normally used) was "repaired" ~ 2 years ago to remove 3 major bumps. The runway bumps are so bad that take-off roll requires keeping forward pressure on the nose until passing the bumpy area to avoid premature launching airborne. I have landed on 13 many times and always get an unpleasant bounce and have to work to maintain the landing. Landing long beyond the washboard is not practical as the runway is too short.
The facts we know: (1) the pilot was unfamiliar and needed tower assistance to find the airport, (2) 701JM was high on final, (3) 701JM did not have speed brakes, (4) Managing speed is essential, (5) Mooney's porpoise, (6) eyewitness noted the airplane hit hard and bounced, (7) eyewitness reported a prop strike, (8) Listen carefully to the Live ATC recording and you can hear the stall warning horn during his last radio communication (9) Unless you are based or operate @ KPAO its hard to know about these unsafe runway conditions.
This may very well be a case were a pilot, unfamiliar with the runway conditions, was high and fast and encountered a nasty washboard runway surprise followed by the well known Mooney porpoising behavior that resulted in a prop strike, then was unable to develop power to successfully go around thus resulting in a stall spin.
The airport sits on the bay and the tide goes in and out twice daily thus causing the runway to move. The Runway 13 end is closer to the bay than 31. The tidal affects on the asphalt are strong. The holes in the asphalt on the airport will show signs of salt residue many days. The asphalt and base layers are so thin the weeds grow prodigiously in the many cracks. The runway was constructed years ago, long before the civil engineering practices and finances were in place to stabilize the surface.
The airport has started a 3 - 4 year project to repair the apron and just completed the first phase. This consists of removing all the asphalt and "base" layers, and replacing the base layer with a mixture of compacted granite and concrete (25% concrete) to create a stable base, then laying new asphalt. I am not certain what are the plans to address the runway.
Those of us whom operate out of KPAO are thrilled the City has a plan to upgrade the airport and repair the deteriorating facilities. Perhaps this tragedy will prompt discussion to understand the runways potential involvement in the accident and if it is credibly determined to be in the accident chain, prompt prioritization of repair.