Date: 202009
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: Rain; 10
Light: Dusk
Aircraft: Honda Jet
Operator: Air Taxi
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Landing
Reporter organization: Air Taxi
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Second reporter function: Captain; Pilot Flying
Anomaly: Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Runway; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Aircraft; Airport; Procedure; Weather
Primary problem: Weather

Narrative: During flight after obtaining the weather at [the] destination; [the] Captain and I decided that [the] most suitable runway for [the] given conditions would be the longest. Appropriate for landing would [then] be RNAV LP+V GPS Runway XX; available runway [at the longest length for the airport] - winds were calm; VIS 10; ceiling 1800; temp 27. Once we both agreed; I start programming the FMS for LP+V GPS Runway XX; selecting wet runway conditions and adding 1.15% factor for wet runway. Landing weight was well below max landing weight. Based on that; [the] distance required to land on Runway XX was [calculated]. There were no PIREP for braking action on Runway XX.ATC vectored us for descent and [we] were told to expect RNAV GPS Runway XX in ZZZ. We were given descent to 1800 and direct to ZZZZZ. [We] configured the aircraft prior to crossing ZZZZZ; [the] checklist was completed [and the] aircraft was configured for landing with autopilot engaged up to 300 ft. We did have visual contact with the runway at 1600 ft. I; as [Co-Pilot]; called all speeds; altitude and on glide slope and minimums which Captain was right on everything. At about 300 ft.; [the] Captain disengaged the autopilot and did a smooth landing on Runway XX. After touchdown; speed brakes were extended and brakes were applied. Halfway down rolling on Runway XX; [I] told [the] Captain that this thing wasn't stopping at all [and it] felt like we were sliding on ice; there was no friction between the main tires and runway surface. He responded I have max braking and [the] aircraft [was] hydroplaning. About 1500 prior to runway ending I said we are going for grass area. He responded yes; we are going straight for grass area. Aircraft came to rest 100 ft. to 150 on [the] grassy area. After full rest on [the] grass area; we assessed and ran the shutdown checklist. Then I exited the aircraft to do [the] post-incident check followed by [the] Captain. We both did not see damage to aircraft and we were both sure hydroplaning was the factor; otherwise we would stopped on the runway. We have been to this airport before.


Second narrative: During our Part 91 flight to ZZZ; an incident occurred where the aircraft overran the available runway length. On descent into ZZZ; my SIC and I discussed plans for the arrival. Based on calm winds and approximately 1;700 ft. ceilings; we decided the RNAV GPS LP +V approach to Runway XX would be the most optimum approach given our direction of flight; since Runway XX was the longest runway. The [Co-Pilot] programmed the FMS based on the ASOS report and the XM weather loaded into the FMS. I confirmed the runway; the weather; and confirmed that 'wet' runway conditions were selected. Landing distance factor was set at its default value of 1.15 providing additional margin. After the incident; I returned to the aircraft and re-ran the same numbers to confirm that the FMS computed Actual Landing Distance Required was [the same as the calculation during the flight] and that our landing weight was computed at [the same weight as calculated during the flight] and was below the maximum landing weight for the aircraft.At the beginning of the approach; after being vectored for weather; we were given direct to ZZZZZ; an initial fix on the approach. We proceeded direct to ZZZZZ and were given a descent to 1800 ft. By this time; we had configured with approach flaps and had completed the approach checklist and briefing. Roughly a mile before ZZZZZ; I configured with landing gear down and full flaps. We completed the before landing checklist. Crossing ZZZZZ; we slowed to approach speed and the aircraft started down on the approach on autopilot. We broke out and had the runway in site well in advance of minimums. There was light rain on final. We approached the runway at Vapp and around 50 ft.; I pulled the power to idle in order to slow further to Vref and aimed the aircraft for the runway numbers so as to touch down before the thousand-foot markers. At this point; I deployed the speed brake and applied the brakes increasing to maximum braking. Braking action was very poor and we were slowing but even with maximum braking and the speed brake deployed - landing performance does not consider speed brake deployment - it was apparent the aircraft was not going to be stopped in the available runway length. Differential braking during the landing roll was ineffective so maximum dual braking was applied and a combination of nose wheel steering and rudder were used to maintain the centerline. Knowing we were likely to depart the end of the runway; I maintained the centerline so as to avoid the runway end lights and we entered the grass area beyond the end of the runway. We decelerated quickly; but smoothly at that point in soft dirt and grass; coming to a stop roughly 100-150 ft. beyond the end of the runway. We assessed and shut down; inspected the aircraft and helped coordinate moving the aircraft to a safe location. The aircraft had no externally visible damage and there were no injuries. Later inspection by [Company] technicians confirmed no damage to the aircraft and no repairs required. No airport property; other than the grass; was damaged. Based on what we observed and the standing water we found on the runway after the landing; the conclusion we came to was that the likely cause of the overrun was hydroplaning of the main wheels on a 'contaminated' rather than 'wet' runway resulting in extremely poor braking action and inability to stop in the available runway length.


Synopsis: HondaJet flight crew reported overrunning the runway due to contaminated runway conditions leading to poor braking on landing.