Originally Posted by PerfInit

I cant speak to the ATC side, although you might find some info in their guidance handbook- FAA JO 7110.65W. The best answer from a pilot perspective is, it depends on the situation. Unless otherwise specified, TERPS is predicated on a minimum climb gradient of 200ft/nm for obstacle avoidance. Yes, there is also the requirement to advise ATC when climb rate is less than 500fpm. Rarely is this an issue unless at or near the max altitude capability of the jet. Most FMS software are predicated on climb at a specific airspeed and thrust setting, thus the actual climb rate varies. Also Most FMS software are "buffered" for smooth level- offs in that the last 500-1000ft are at reduced climb rate (mainly for pax comfort). The Airbus FMS always tries to achieve a 1"g" ride and will put pax comfort first over trying to meet a climb/descent restriction. "Managed" mode in the Airbus can get pilots in trouble if they don't understand how it works. I probably have not fully answered your question, but I Hope this helps a little bit at least..