If you want an interesting read, check out
http://www.atsb.gov.au/aviation/pdf/vh-inh.pdf.
It's the 1996 final report on the Ansett 747 accident at YSSY. Gear warning horn features very prominently.
High Altitude, you would need to worry if Viper happened to be a 747. Three greens not nearly enough, not even four as was called on the Ansett 747. Now if they had seen five...............!