Date: 201606
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Takeoff / Launch
Reporter organization: Air Carrier
Reporter function: Dispatcher
Reporter qualification: Dispatch Dispatcher
Human factors: Workload; Time Pressure; Situational Awareness; Confusion; Communication Breakdown
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Human Factors; Company Policy; Procedure
Primary problem: Company Policy

Narrative: The original captain timed out after a taxi out delay and 2 reroutes from ATC for weather impacting departures.The CREW SYS message didn't show up warning me the captain was going to time out; the captain was on the phone with me and let me know. We made the decision to return to the gate because the crew could not make it to the active runway in 4 minutes. The time he was citing was XA:22Z as a last wheels up time. The crew blocked into the gate at XA:25Z. At XA:27Z the automated crew sys message popped in saying the pilot had exceeded a limit.A new captain was assigned the flight. They pushed the gate at XC:27Z. At XC:32Z another message pops in saying the First Officer has exceeded a duty limit. I called the Dispatch Manager and said; can we verify with scheduling please? He was already aware of the message and said 'it's too late; they're rolling down the runway' I informed him this message came too late and was possibly a distraction for my crew. He told me that the system knows when they are on the active-the crew won't get chimed. I pointed out the chime may be silenced because they are on the ground-but the light will illuminate-again possibly distracting the crew as they are rolling for takeoff.The weight off wheels message came across at XC:33Z.I asked the Duty Pilot for clarification; are we ok to let this flight continue? He said that the crew was legal when the throttles were pushed forward.Here are some messages:These automated messages are being sent late and during critical phases of flight. I suggest scheduling come up with a better way to track duty limitations or increase the amount of time they allow as a buffer for replacing or notifying a crew member. Perhaps replacing a crew member at the 10 minute mark instead of a last minute alert that a crew member is illegal. These messages popping into the cockpit during a takeoff roll are not acceptable and this crew noticed this message; I maintain this is a distraction and possibly creates an unsafe situation. In this case; the crew saw the message; continued their take off and then contacted dispatch to find out that scheduling says 'let them go'.Crew system uplink message popping into flight deck during critical phase of flight possible distraction/safety hazard.




Synopsis: A Dispatcher reported a flight's Captain was removed at his FAR 117 duty time limit. Two hours later during the takeoff roll; the First Officer was notified via ACARS that he had exceeded his duty time limit. Reporter stated they should have received notification earlier and ACARS messages during takeoff should be prevented.