Date: 201312
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Night
Aircraft: Falcon 20FJF/20C/20D/20E/20F
Operating under: Part 91
Flight plan: IFR
Mission: Ferry / Re-Positioning
Flight phase: Landing
ATC / advisory: Tower ZZZ
Aircraft component: Normal Brake System
Component problem: Malfunctioning
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Distraction; Time Pressure
Second reporter function: Pilot Flying; Captain
Anomaly: Aircraft Equipment Problem Critical; Ground Event / Encounter Object; Ground Excursion Runway; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Object
Detector: Person Flight Crew
When detected: In-flight; Taxi
Result: Aircraft Aircraft Damaged; Flight Crew Took Evasive Action; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: I operated the flight that night. We were cleared for the visual approach and cleared to land Runway 6. We completed all checklists prior to landing. The aircraft touched down on Runway 6 at a normal speed; Vref or so and was firm in nature. Airbrakes were deployed and indicated normal. I felt a light brake grab and the Captain called out 'good brakes' as per SOP. After a few moments I realized that we were not decelerating properly and the Captain was in some distress trying to apply the brakes. He reached up and attempted to disarm the antiskid and the airplane seemed to lurch and momentarily grab. He then tried the secondary brake system with no change in performance; he then commanded me to assist and try my brakes. I pressed my brake pedals and found some braking action to be (1/4 of normal at the most) and found that I had to press extremely hard to get that amount of braking action. We then saw the end of the runway coming with a significant cliff/drop off directly off the end of the runway and we had considerable speed left. The Captain turned the airplane to the right with an attempt to stay on the taxiway area as we knew that there was flat ground in that direction. We departed the runway with the right main gear only prior to the intersection in attempt to make the turn. That slowed us down considerably and the Captain was able to continue the right turn. We departed the north side of the taxiway with all 3 wheels and hit several taxi lights. The Captain continued to turn right to avoid the cliff. The aircraft decelerated in the mud to a controllable speed and with the continued right turn we ended up on the parallel taxiway. We let Air Traffic Controller know of our emergency; that we were OK and the aircraft appeared to be OK; but that we had departed the pavement and damaged several lights.


Second narrative: On landing; aircraft braking appeared to be good. 1;000 FT down the runway; it was apparent that there was insufficient braking to stop the aircraft on the runway. I turned the anti-skid off; no help. I went to Number 2 brakes; no help. Based on training received; I went back to Number 1 brakes and requested PM to assist with braking. This slowed the aircraft; but not enough to make a normal exit off of the runway. At this point; we were approaching the end of the runway; after which there is a drop-off to a road. Trying to further slow the aircraft; I began a slow right turn; which brought both right main tires just off of the pavement. I estimate our ground speed at 60 KTS at this point. This slowed the aircraft; but our momentum carried us across the runway end taxiway and onto the grass. Continuing our right turn; we contacted four taxi lights. Being on the grass; we slowed further; and continued that right turn back onto the taxiway. At this point; we were slowed to an estimated 5 KTS; and I chose to engage the parking brake. The aircraft stopped. We shut the airplane down; and contacted the Tower to advice of our situation; and that we were OK. We contacted Operations; and then had the aircraft towed to the ramp. Our post-flight walk around showed no obvious signs of damage to the aircraft.


Synopsis: During landing neither F-20 normal nor alternate brakes operated normally so near the runway's end; the Captain turned the aircraft off the runway across a muddy grass area; contacting several taxi lights and the re-entering a taxiway where it stopped with little apparent damage.