Date: 202102
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower ZZZ
Aircraft component: Airspeed Indicator
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Other Take Off
Result: Flight Crew Overcame Equipment Problem
Contributing factors: Procedure; Aircraft; Manuals
Primary problem: Aircraft

Narrative: At approximately 100 kts; I noticed and called out a IAS Disagree warning indication on my PFD. I immediately looked at the First Officer and the STBY Airspeed indicators to compare speeds and saw the same warning on his. The difference in speed between both was about 5-7 knots (see FM; Airspeed Disagree Alert (amber) Indicates the Captain's and First Officer's airspeed indications disagree by more than 5 knots for 5 continuous seconds); and took about 5 to 10 seconds before the warning went away. My decision was to continue the takeoff since the IAS discrepancy was small and we were in the High-Speed regime. Following the disappearance of the warning indication; I closely monitored the speed differences which was reduced to 1-1.5 knots. Throughout the rest of the flight. An ELB write-up was made and local maintenance contacted to give a full description of the event after landing.Once we were at a safe climbing altitude; we discussed the situation further. I mentioned that if the difference in IAS had been larger I would have opted to reject. Interestingly; the First Officer expressed relief that we did not reject; and that we could have taken off even with the stick shaker going off; similarly as we experienced in a recent MAX training session (during climb); and that the company does not want us to reject other than for the exceptions stated in the FM. His honest answer left me to ponder and wonder if I made the right decision; and to take a closer look at our Normal and Non-Normal procedures; guidance; and its implications; and if any further clarification is needed or due. With that said; I would like to review on how would they apply in the following scenarios. For ease of page reference; I utilized FM dated XX-XX-XXX; however the manual date at the time of the event was [on] YY-YYY-YYYY. The information appears to be identical with the exception of a slight page numbering difference.  As a point of reference to determine a reliable airspeed indicator; the checklist states 'An airspeed indication that differs by more than 20 kts or 0.03 Mach from the airspeed shown in the table should be considered unreliable.' Also; there is NO guidance for pitch attitude on takeoff for this situation other than an initial pitch to 15 degrees followed by the immediate actions; which would call for a pitch and thrust reduction just off the ground following gear retraction. The immediate above action items seems contradictory to safe and sound practice of flying away from the ground and executing an emergency procedure at a safe altitude. Should safer guidance be included?It seems very clear; as always; that excellent flying skills and judicious Captain's Emergency Authority will be needed.

Callback: Reporter stated his main concern is he feels the procedure for dealing with IAS disagree scenarios is a vague and potentially misleading.  Reporter stated the issue seemed to resolve itself within just a few seconds.



Synopsis: B737 NG Captain reported an airspeed split on takeoff roll and elected to continue. Post flight and reviewing the incident; Captain described misgivings over published policy.