cougar

This is the epiphany I had about 20 years ago when I first started instructing on Boeing aircraft. The whole concept of a CDFA is that the airplane arrives at the MDA at the VDP simultaneously, therefore the VDP is rendered an atavistic term from the dive and drive days.

Further, since the DA/DDA is coincident with the VDP when using CDFA procedures, any level off at minimums likely leads to an unstable approach due to immediately being high relative to the intended glide path. This in my view is a far greater risk than forgetting and flying through minimums. As Adlerdriver pointed out, we seem to remember minimums just fine on ILS approaches. Moreover, the “approaching minimums” and “minimums” call outs are available as automated calls.

Training is the foundation for CDFA procedures, to ensure crews understand that once the descent has started at the FAF, there is no change, no ‘getting down early” etc. Maintain the briefed descent mode/rate, once at minimums (DA/DDA), continue if runway environment is in sight, or go-around.

For example, all Non-ILS approaches on the 747-400 can be flown in VNAV, therefore VNAV PTH is the required FMA from the FAF until the End of Descent point per our company procedures. If the FMA changes from VNAV PTH to any other mode inside the FAF, it requires a go-around.

If V/S is required to fly the approach (this would only be necessary due to some NOn-normal), then once the calculated V/S descent rate is set at the FAF, is doesn’t change. At DDA, continue or go-around.