HUD-based hybrid landing systems developed by SEXTANT Avionics have been successfully certified for AEROPOSTALE and ALITALIA. The philosophy of such system is to offer minima reductions (down to DH 35 ft and RVR 125 m) with automatic Cat 3A operations. From a human factors stand point, the basis of such an approach is that improved situational awareness provided by the HUD allows to maintain an acceptable safety level for operations despite lower DH and visibility. Though, it is well known that switching from a supervisory control mode to a manual control mode under time pressure is a very serious challenge for the human operator. In this regard, numerous human factors issues were addressed during the concept validation phase and results applied to certification. This was particularly true for difficult exercises , as manual go around at DH with one engine out on the B-737, where it had to be demonstrated that specific information provided in the HUD allowed to keep an acceptable level of safety. Training issues are also of importance to operate the aircraft and in-service operational feed back start now to be available.