EMB-505 flight crew reported a runway excursion occurred while taxiing across a runway at night in inclement weather.
Synopsis
EMB-505 flight crew reported a runway excursion occurred while taxiing across a runway at night in inclement weather.
Narrative
Flight crew arrived at the FBO at XA:00 after 10 hours of rest due to late trip changes the prior evening because of deferred DME impacting ability to perform the originally assigned trip. Previous afternoon's flight in as PF; I exited runway XX at taxiway 1 and was thus unaware of the design of the intersection of taxiway 1 and runway XY. Moderate rain showers had just ended prior to arriving at the FBO with an overcast layer at 1400 AGL. The field was uncontrolled at the time. Crew preflighted the aircraft per SOP and discussed threats prior to taxi; including the darkness and wet ground. The intersection was briefly discussed; but lacking a hot spot designation; no further inspection of the chart was performed. As neither the tower nor approach were open yet to pick up a clearance; flight crew decided to continue and taxi out to avoid delays impacting the next live leg; with consideration for weather at that leg's destination airport. During taxi out; the wind had reached a peak gust of 28 knots; pushing the aircraft directly from behind along taxiway 1. As PF; I utilized the brakes to keep ground speed at a manageable pace. Flight crew was also focused on reaching the departure end of runway XY in order to pick up clearance from ZZZ Approach; as advised by ZZZ Center. Briefings and checklists were completed prior to reaching the intersecting runway XY and PM made a call on CTAF. At this point; the airport diagram was zoomed to an area where the intersection was not visible. Seeing a taxiway designation sign on the left side and lacking ability to see lead off lines due to the darkness and wet condition of the runway; I continued ahead as the taxiway designation sign became visible. Realizing the continuing taxiway is not located as expected; brakes were applied approximately 75 feet prior to the edge of the intersecting the runway. However; with the condition of the asphalt surface; strong winds pushing us forward; and brakes already hot due to continuous application during taxi; the aircraft slid off the runway and into the waterlogged grass/mud and came to a stop. A check of the engine and flight instruments showed no abnormalities or CAS messages; so a normal shutdown was performed. All relevant Company personnel were notified. Tower was notified after they opened to ensure a NOTAM was issued for taxiway 1 and runway XY. No injuries were sustained by the flight crew or anyone else in this event. Identification: Runway edge lights became visible shortly prior to the realization that the taxiway did not continue straight ahead. At no point were runway markings or surface markings visible to give indication of the correct path to follow and continue onto the taxiway. Cause: Main causes as perceived include the adverse weather conditions; such as night time darkness with low overcast layer and wet glistening surfaces obscuring the taxiway lead off surface markings; and strong gusting winds from directly behind continuing to push the aircraft at a quick and steady pace. As well; the lack of a designated hot spot or prior experience with the offset/dogleg taxiway A at the intersection of runway XY; with a chart that was not correctly positioned to view the intersection prior to crossing; contributed to the late reaction and application of full braking. Finally; seeing a lit taxiway designation sign directly perpendicular with direction of travel gave false affirmation that the continuing taxiway was directly ahead. Response: Full braking was applied in an effort to stop the aircraft prior to reaching the edge of the runway; to no avail. As the aircraft exited the paved surface and burrowed into the mud; flight controls were kept neutral in an attempt to avoid swerving or otherwise unintentionally inducing side load and possibly collapsing the main and nose gear assemblies. A scan of the engine and flight instruments was performed and noting no abnormalities or CAS messages of any kind; a normal shutdown was performed. As PIC;I initiated contact with Company personnel; including Flight Communications; chief pilot; and Maintenance Control. ATC was contacted as well after tower had opened to notify them of the situation and request a NOTAM be issued. Suggestions: A hotspot designation on the airport diagram at the intersection of taxiway 1 and runway XY would better draw attention to the design of the offset/dogleg taxiway. As well; lit taxiway lead off lights can also give a better indication of how to traverse the crossing. In handling the aircraft; more brakes in an attempt to slow down the taxi ground speed even more could have given more time to react to the situation. Ensuring all available information/charts is presented and easily viewable during ground operations could give greater insight into any discrepancies in terms of design or shape of the airport surfaces to aid navigation.
Second reporter narrative
Flight crew reported for duty at XA:00 local at ZZZ. Originally scheduled for a XB:00 duty time; due to operational needs; a late night change advanced our duty time to a few hours earlier. Preflight; cockpit setup; engine start completed per company standard operating procedures. Threats for taxi and takeoff were discussed; ie: uncontrolled field; night; wet taxi surfaces after moderate rain that has just passed through the area. Began taxiing and operations off to a normal start. Checklists were conducted in an orderly fashion in low areas of venerability. As approaching to cross runway XX; as PM I made our position call and our intentions of crossing the runway as well as turning on lights and scanning the area/final for possible landing traffic. At the time; our departure clearance was still not obtained and the anticipation of receiving the clearance once clear of the crossing runway. With the taxiway location/designation sign directly ahead we continued forward. It was prior to half way crossing runway XX that the runway edge lights were visible and the actual taxiway was 45 degrees to our left. Captain/PF heavily applied brakes; but due to wet surfaces; strong tailwinds it was too late.Identification:Captain/PF prior to half way crossing runway XX applied brakes recognizing that the taxiway does not continue directly ahead. With the taxiway 1 location/designation sign directly ahead; the assumption was so was the rest of the taxiway. Cause:Night time; uncontrolled field; stronger tailwinds on the taxi (25kts) than anticipated with wet taxi surfaces in an unfamiliar field were contributing factors to taxiing off.With rain that recently passed through the area; an overcast ceiling blocking any possible natural lighting from the moon; obstructed taxiway center line markings indicating the 45 degree turn. Response:Captain did a great job securing the aircraft afterwards; as well as immediately contacting Flight Operations; Chief pilot; Maintenance. Due to the early hours; airport operations and ATC were not available and unable to be reached. While taxiing I recalled hearing airport maintenance vehicle on the radio and reached out to him and he was able contact his supervisors and fire department.Once in hours of operations were in effect; we were able to verify that the correct NOTAMs were in place.Suggestions:Even though we reviewed and briefed the taxi diagram; a hotspot on the taxi chart at the intersection would help prevent others from veering off and highlighting the drastic change of direction of the taxi way. Other suggestions would be taxi way center lights depicting a change of direction.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.