Air Canada A320 accident at Halifax

[Retired DC9 driver]

ATC watcher,,,
Re HUDs; I corrected my post..

Note for peekay4, just so all understand this exemption,
regarding the "descent below MDA" on a non precision approach. CARs says later in the document
"This exemption is required in order to accommodate the altitude loss below MDA that will likely occur during a missed approach, following a stabilized constant descent angle (SCDA) non-precision approach".

so you could descend below MDA still in IMC conditions under this exemption, but only during the execution of a Go Around..In the past, the 50 foot "buffer" would ensure, that even during a GA in IMC,the aircraft would never descend below MDA.