737NG (800/900ER) off-route waypoint sequencing
 

Reference GOLD version 2, the 737 in cruise should see off-route waypoint sequencing within 21nm of the route (XTK ERROR less than 21nm). I could not duplicate this in the simulator (it did not work at 19nm XTK ERROR), and have not had the opportunity in the jet.

The scenario is a weather deviation using HDG SEL and not adjusting the active route (not executing an offset). Does anyone know the actual distance? If so, is there a source reference for this?

Here is the GOLD excerpt:

Boeing B737, B747-400, B747-8, B757, B767, B777, B787, MD90
Waypoint sequencing will only occur when the aircraft is within 21 NM of the aircraft active flight plan route (as modified by any parallel offset that may have been entered). Therefore ADS-C waypoint change event report and armed UM 130 REPORT PASSING message will not be transmitted automatically when the aircraft is outside these limits.

Verified in the jet
 

In case anyone is interested, I verified in the aircraft that the Boeing statement is correct. Waypoints will properly sequence when within 21nm of the active route (XTK ERROR 21nm or less). During a weather deviation we had a 20nm XTK ERROR when the waypoints sequenced.