What defines a field fault?

I looked through the manual but could not seem to find reference to it anywhere. Does anyone have a link to official FRC documentation as to what a field fault is?


I could be wrong but IMO , FF are up to the Head Ref and from my understanding it is a fault that would likely affect the outcome of a match at the Head Ref discretion withe communication and agreement of the FTA.

So for instance a defense may get loose but if its not super loose or even if it is … if the defense was destroyed already then calling a FF would not likely affect that match in any fashion…so its less likely to be called in that scenario.

Each potential FF situation is evaluated at the time.

I saw a FF called due to tablets not working with FMS for instance is another scenario.

Field faults may also be due to any control system issue that the field experiences, such as a counting issue of boulders going in or the ref’s tablet for scoring not working. Field faults are not just up to the Head Ref, but the entire key crew (i.e., Field Supervisor, CSAs, FTAs, etc.) working the field may call it, once it is seen.

Game Manual, section 5.5.5

5.5.5 MATCH Replays
Over the course of the Tournament, ARENA FAULTS may occur. An ARENA FAULT is an error in ARENA operation that includes, but is not limited to:

  • A. broken FIELD elements,
  • B. power failure to a portion of the FIELD (tripping the circuit breaker in the PLAYER STATION is not considered a power failure
  • C. improper activation by the FMS
  • D. errors by FIELD STEWARDS
  • E. a Team STANDARD falling into the FIELD

T20 If, in the judgment of the Head REFEREE, an ARENA FAULT occurs that affects the outcome of the MATCH and any team on the affected ALLIANCE desires a replay, the MATCH will be replayed.
All reasonable effort is made to create the same conditions when replaying a MATCH. This means, for example, that a Team which was BYPASSED during the MATCH which is to be replayed, is BYPASSED for the replay MATCH. The DEFENSES used during the MATCH which is to be replayed are also used for the replay MATCH.

I had to describe some of the times it is appropriate to contest matches to a student at the Colorado Regional and I did so roughly like this.
If for some reason the FIELD falls out of specifications in a way that makes it impossible to play the game in a way that is safe to all those involved and fair to both sides (effects the outcome of a match or prevents the match from being played properly) to those involved then a field fault then you CAN POLITELY ask if a field fault could be considered. Keeping in mind that it is also well within your right if a field fault causes a match to be replayed directly after a completed or mostly completed match you can ask if a Field Timeout could also be considered.
Otherwise don’t blame your bad battery or loose connections on the field.

I will admit this is always my least favorite part of the manual to read because I’ve never needed to cite it due to a “positive” circumstance.

The most common “field fault” I have seen, that causes the match to be replayed, is the defenses being placed improperly.

In 2014, there was an FMS issue where it sometimes sent a 2nd Autonomous Init to a robot about 8 seconds into Autonomus (or something like that). It did not happen to all the robots in the field. We could see it when it happened to our robot. If we were the loosing alliance, it would be a reason to ask for a Field Fault and replay the match.

Based on what GeeTwo posted for us, the direct and simple answer to your “What defines a field fault?” question is: The Head Referee

It also happened twice to the #1 alliance in QF1-1 at 2014MICMP

Stuff I’ve seen trigger one:

Portions of the field becoming detached from their mooring (usually it’s a defense–rock wall, ramparts, and moat are the most common), including side panels and/or gates. It’s kind of hard to score a crossing when the robot hasn’t finished crossing the defense, but the defense is already damaged (as in, it’s halfway across the courtyard!). That being said, a slight move probably won’t trigger a field fault.

Tablets freezing–especially if it’s an outerworks tablet. Even if the score is correct (thanks to manually counting and entering later), the teams can’t see that they’ve scored a breach. On an unrelated note, teams taking their carts across the cable protector between the field and the scorers table greatly increase the risk of this happening, so don’t do it if you like to not have field faults.

We had a fascinating one in the finals of this year’s Pacific Northwest District Championship. Here’s my best recollection of what happened:

The defenses were set up incorrectly, and the field “pre-start” was initiated before it was noticed. They fixed the defenses, restarted everything, and ran the match. Team 1425’s robot was immobile for most of the match, then ran into the wall until it was e-stopped (looked like it might have been running autonomous routine).

After the match ended, no score was announced, as the head referee, FTA, and table staff conclaved for a very long time (I believe it included a call back to FIRST headquarters). Then they announced the field fault. They said that it was known previously that 1425’s robot needed to be tethered and re-initialized after a “pre-start” before it would respond properly to another “pre-start”, and that the team had not been given a chance to do that. That made this a field fault.

The match was replayed, and this time 1983 (Skunkworks, the alliance captain) disconnected for half the match, so the outcome was the same.

The field fault match and the explanation for the replay don’t seem to have been included in the Youtube playlist, so I wasn’t able to double-check my memory. If anyone has more details, please add them!

(The alliance had already lost the first match playing two-on-three with the third robot undergoing repairs. An astounding run of misfortune… but 1983 still ended the event in the #1 position for the district. Hopefully they’ve now used up all their bad luck quota and everything will be great at St. Louis!)

At the Orange County Regional one of our matches had no sounds, and no lights on the tower. We asked the head ref. about it and they didn’t do anything about it.

A different flavor of event that thankfully didn’t trigger a field fault happened at FIM Lakeview. Before one of our matches, the sun moved into a position shining through some windows that made the field nigh invisible for the red alliance. Powered curtains were lowered before the match as started as everyone could see this was a problem (that would last at least another hour).

I’m glad it didn’t happen during a match.

At SVR, the very first match on Friday saw a field fault. This was due to none of the game sounds going off. When autonomous ended, some refs and teams alike had no idea because there was no sound to indicate. It was a full 10 seconds before we realized and stopped the match!

At one qualification match at Montgomery (I don’t remember the match number), a field fault was called because a standard holder came loose after a robot banged into their driver station. The standard fell into the field and on top of the robot that banged it. The robot seemed fine and was able to get the standard off, but a field fault was called nonetheless (probably to protect the standard more than the robots).

In general, if it is a problem with the Field or FMS that is caused by Field Personnel or FMS, then it is a Field Fault.

Acts of God can go either way.

Stuck Portcullis gate: Probably a Field Fault (not working the way it should)
Cover for Sally Port is knocked off by a robot: Probably Field Debris (can be reasonably anticipated from its design).

There’s 3 parts to a field fault. They are stated in the rules, but basically they are:

  1. There was a problem with the field which caused an arena fault. Something came loose (like a defense), some electronic error occured (ref tablet, ball counter failed), or some other thing happened which raised the question.
  2. The fault (likely) affected the outcome of the match. For example, if a defense comes loose, but it has already been breached and no one tries to cross it again, likely didn’t affect the outcome of the match. If a team got stuck on a loose rock wall, likely affected the outcome.
  3. A single team on the alliance that was affected has to request a replay. Doesn’t have to be all 3 teams or a majority, just one of them.

All 3 of those conditions must be met in order to perform the replay. You may be thinking why all 3 are required, especially when the field fault was obvious and affected the outcome of the match. This actually happened to me at KC this year. I can’t remember exactly what happened (maybe a ref realized he missed some crossings or something), but the match continued to play out. We (the head ref and I) discussed after the match and decided it was a field fault. I went and talked to each of the teams, and they decided not to replay the match. Their reasoning was that they won the match and got the 2 RPs and didn’t want to risk losing the rematch and thus losing those RPs.

This is a pretty accurate description of what happened. The only addition I would include is that in the last match 1425 also lost connection for a period of time so we were playing with only a single robot (2907)

I just want to say that the other alliance ( 360, 4469 and 3238) played a terrific finals and they were a very deserving winner!! Even if we had all of our robots playing we would have had a difficult time beating them.

Thanks for the good wishes!! Given that the only connection issues we have had in 75 matches so far this season were in the finals of a district and the District champs finals we also hope that our luck turns.

Historically, AV issues are not typically considered field faults, as they are not part of the FMS/Field system. This includes sounds and score/clock display on the screens (the official clock is on both alliance walls). A single instance of sounds not working can definitely cause confusion, but I have seen several consecutive matches played in years past without Auto or End Game sounds - at the time teams were alerted to watch the official field clock.

Your recollection matches pretty well with what I have heard as well. It was a very bizarre scenario that our robot woke up mid-match and ran into the sidewall until E-stopped. I had also heard that they thought autonomous was triggered, but we have no auto mode that would have produced that set of behaviors observed (all auto modes drive time-based for only a few seconds). In addition to the drive motors running continuously, the collector drove down against the hard-stop, and the climber release motor (typically only triggered for a second or so per match) stalled, smoked, and seized before E-stop was pressed, requiring replacement before the replay.

We don’t need to tether between matches to re-connect, but frequently must reset the RoboRIO to get a stable connection with the field. It is something the FTA’s are aware of, and an ongoing pre-match connectivity hiccup we are working to root-cause. It seems that redoing pre-start may have had an effect on our connectivity that was not noticed prior to the start of the match.

Throughout Finals, the opposing alliance captain from team 360 demonstrated superb gracious professionalism, both in offering up their timeout to make sure 2907 could make it to Finals 2, and by insisting on a replay of Finals 2 without hesitation after the field fault. Their entire alliance played well and are very deserving of the win. We look forward to seeing them all in St Louis.

That continues for this year, as well. Blue Box, T20:

Note that an ARENA FAULT that does not affect MATCH outcome in the judgement of the Head REFEREE does not lead to a MATCH replay. Examples include, but are not limited to:
A. a piece of FIELD plastic falls into the FIELD in the last 5 seconds of a MATCH, far away from any human or ROBOT activity, and in such a way that it does not affect MATCH outcome
B. delay in the playing of an ARENA sound
C. mismatch between the timer on the Audience Screen and the FIELD Timer