Date: 201907
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Citation Excel (C560XL)
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower ZZZ
Aircraft component: Antiskid System
Component problem: Failed
Reporter organization: Air Taxi
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Workload
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Runway
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Rejected Takeoff; General Flight Cancelled / Delayed
Contributing factors: Aircraft; Human Factors
Primary problem: Ambiguous

Narrative: We conducted the cockpit briefings; loaded the 5-passengers and their bags; taxied to the Runway XX for departure. The Tower gave Aircraft X instructions line up and wait. The Tower cleared the aircraft for takeoff. The First Officer called 70 knots; then V1 (3-5 knots below V1); then abort; abort; abort; abort; abort. I immediately reduced the thrust to idle; applied braking and deployed the thrust reversers. As the abort continued down the runway; I (PIC (Pilot in Command)) had full left rudder pedal to the floor and asked the F/O (First Officer) to push on his left rudder just confirm the pedal was depressed and his brakes worked. It appeared the right brake was engaged even though I was only pushing on the left brake pedal. The aircraft remained on the centerline until the last 500 ft.; then began to veer right. I was unable to keep the aircraft on the runway. The aircraft veered right into the grass on the runway edge and came to a full stop. The engines were immediately shutdown; and the First Officer went to check on the passengers. I conducted the After Landing & Shutdown checklists to secure the aircraft and my First Officer met with the fire and rescue and moved one of the passengers outside for an evaluation. No one injured during the abort.


Second narrative: Aircraft X was told to taxi onto Runway XX and position and hold. We complied. After we were cleared for takeoff the Pilot Flying added takeoff power; called Power Set. I was the Pilot Monitoring. Prior to calling 70 knots the Anti-skid annunciator came on for a second or two and disappeared. This had triggered my mind that if I see that light again I was calling abort. The annunciator panel was clear and the only light illuminated was the ground idle light. I called 70 following which I called V1 approximately 3-5 knots prior to the actual V1 speed. As I was calling V1 the Anti-skid annunciator came on again and was accompanied by the Master Caution. I called abort; abort; abort and the flying pilot's hands were still on the throttle. The Pilot Flying promptly aborted the takeoff. As the airplane was decelerating with thrust reversers and brakes I checked in with ATC and told the Tower we were aborting the takeoff and stopping on the runway. The [Controller] in the Control Tower asked me if we needed any assistance to which I replied 'negative; no assistance needed at this time'. The Pilot Flying was in full control of the airplane and was maintaining the centerline. The airplane all of a sudden felt like we were steering to the right of the centerline. At that moment the Pilot Flying asked me to help him with the left rudder. I complied and pushed the left rudder but there wasn't any rudder remaining to push as he had it all the way in. The airplane skid onto the grass adjacent to the runway and came to a complete stop within 20-25 ft. I asked the Pilot Flying to shut down the engines and confirmed engine shutdown. The APU rolled back by itself at this time. I rushed to check on my passengers while the Captain was doing the QRC. I returned to the flight deck; contacted the Tower and told them we were off the runway and required emergency services. Fire Rescue and Airport Operations were on the scene and I opened the main door of the airplane once I had the all clear from them. We had no injuries on board. One passenger was checked by the emergency service personnel as he had anxiety. All passengers were safely evacuated and the Captain and I evaluated the airplane once we were given the all clear by emergency services.


Synopsis: C650 flight crew reported an anti-skid system anomaly on takeoff roll; resulting in a high speed rejected takeoff and runway excursion.