@JASON I was set cruise altitude is by FMC calculated result.So i not get to high altitude. @Omar Before get buffet alert ,i was in stable cruise,then get buffet in the short time.I notice IAS drop down to yellow are.And buffet has two condition is overspeed and low speed??(Thanks you share this page)@Frederic I was meet "something" causing my IAS was drop down.And my speed and altitude is normal before.I just don't know what is reason....i know is low speed to receive alert message. @Kevin I was eat launch before,this alert could be for other people...