Date: 201511
Local time of day: 1201-1800
Location: PAO.Airport, CA
Flight conditions: Mixed
Weather elements / visibility: Rain; Thunderstorm; 10
Light: Daylight
Aircraft: Small Aircraft; High Wing; 1 Eng; Retractable Gear
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Landing
ATC / advisory: Tower PAO
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Training / Qualification
Second reporter function: Single Pilot
Anomaly: Deviation / Discrepancy - Procedural Clearance; Ground Excursion Runway; Ground Excursion Taxiway
Detector: Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Provided Assistance
Contributing factors: Aircraft; Airport; Weather
Primary problem: Weather

Narrative: I was providing [training] on Local Control during the event. The developmental instructed Aircraft X to make a short approach. Aircraft X complied but landed long and had difficulty stopping. The aircraft subsequently rolled past the relocated threshold onto a taxiway and stopped at the edge of the paved surface. The pilot taxied onto the grass and performed a turn back to the taxiway and then exited the runway environment.This airport has a short runway and excursions and similar incidents; such as flat tires due to hard braking; occur multiple times a year.


Second narrative: 15 minutes after landing my aircraft I was confronted by Airport Operations at the small; general aviation airport while performing my post-flight inspection; securing the aircraft and filling out paperwork. He told me that ATC thought that 'they may have seen me go into the stop-way for runway 13' and 'what was your recollection?' I was immediately confused because there is NOT a stop-way for the active runway at the time and having been a Chief Pilot and high-time Flight/Ground Instructor I know that from 14 CFR Part-1; a Stopway means: 'an area beyond the takeoff runway; no less wide than the runway and centered upon the extended center-line of the runway; able to support the airplane during an aborted takeoff; without causing structural damage to the airplane; and designated by the airport authorities for use in decelerating the airplane during an aborted takeoff.' http://www.faa.gov/airports/airport_safety/certalerts/media/cert0003.pdfIn the spirit of cooperation; and knowing most of the Airport Operations folks very well; I provided my FAA ATP Certificate when requested to do so. He stated that 'this was just routine.' They asked me to recollect/describe my taxi procedure/experience and I told him that there was nothing unusual or eventful; except that I had used up most of the runway during landing and turned off at the end of runway on the taxiway due to a lot of standing/pooling water on the entire runway surface and poor braking action. Tower did NOT say anything to me while I taxied off of the runway. ATC Ground did NOT say anything to me after I had cleared the runway and conducted my after landing checklist; or while I taxied for approximately 3 minutes to my parking spot. They returned a second time approximately 20 minutes later very confused and wanted to clarify his misunderstanding/mistake and he confirmed that the runway did NOT in fact have a stop-way. He also mentioned that he was told by ATC that if they did determine/agree that a 'runway excursion' had occurred; that it was not a serious matter; such as a 'runway incursion'; and that 'it is highly doubtful that anything will be filed with the FAA since runway excursions are a common occurrence at PAO.' (This same statement was repeated the following day the ATC facility during my visit. I walked away from the two confrontations and my visit to ATC the following day; totally confused and nervous and this is why I am filing this report.)The following synopsis describes my experience and the events leading up to my speaking with Airport Operations:I was flying solo; Part-91; and entered a right-downwind  after navigating around several thunderstorms; lightning; and heavy precipitation (bad weather day; recently changed to VMC). The preceding controller had set me up very close/tight for the straight-in/direct downwind entry. I was fully configured by mid-field downwind with my gear down/locked and full-flaps. In order to assist ATC and several very stressed incoming pilots I was asked while abeam my touchdown point; and accepted; a short approach. My approach and landing was fully-stabilized (on center-line; glide-path; and airspeed). Immediately upon touching down my main tires I noticed that the runway surface had a lot of standing water; and major pooling; from the very recent; heavy storms. The runway condition was very bad and my braking action was very poor. Despite applying proper braking and aircraft control techniques; I experienced mild hydroplaning and as a result came to a stop at the end of the runway hard-surface. While turning off to the right my left main tire appeared close to; but NOT over; the edge of the hard-surface; nor did the aircraft feel; handle; or taxi as though it had exited the hard-surface. My eyes were focused on getting the aircraft off the runway and taxing. Other than the poor runway condition and braking action; nothing else was unusual about the landing; taxi; and communication with ATC. The aircraft didNOT experience any damage and I did NOT get near any runway lights; signs; etc...I called ATC the following day to discuss their take on what occurred the previous day and was invited on a tour. I met his young staff of mostly trainees. They suggested that I speak with his manager; to find out more and whether or not he/they would file a report with the FAA. When I called he informed me that he HAD in fact already filed a report to the FAA; thus; I am filing this report/outline of events on my behalf to describe what happened from my perspective. In conclusion; I am a professional pilot with 10+ years; and more than 8700 flight-hours; free of any accidents; incidents; violations; or enforcement actions. I just completed 2+ years of very demanding air-ambulance flying as a training captain. Flying in bad weather on wet/contaminated runways is not unusual for me; however; being confronted by Airport Operations during post-flight of a normal operation certainly is. Lastly; due in large part to my respect for; and adherence to; CRM/SPRM/SMS; I immediately volunteered to share this experience with my fellow pilots; Chief Pilot; Director of Operations and upper management in order to make this a learning experience for myself and everyone. My ultimate goal; as always; is to be continuously improving/enhancing our/my safety culture and to inform our/my best-practices.


Synopsis: An aircraft landed long. The reporting Local Controller stated the aircraft stopped on a taxiway edge and had to taxi off the surface onto grass to return to the taxiway (the taxiway extends from the end of the runway). The reporting pilot stated that other than landing long due to wet runway nothing unusual happened. The pilot stated the aircraft never left the runway/taxiway surfaces.