And now having read the Bombardier QRH, I see where they differ. The Bombardier QRH would have directed you to check the alternate verification system if only a green gear down and locked light had failed to illuminate, but if a green light was out and you had other indications of a failure to extend such as gear door open lights on and the gear unsafe light on, you would carry out the alternate extension procedure. I agree that if they'd followed the OEM QRH rather than the Air Nelson one, the incident would not have happened.