We used to add 50ft for pressure error correction(PEC)in piston ops(usually as defined in flight manual)o but turbine A/C appear to not require it,probably due to more sophistication of systems.As for flying a 3deg slope,OK if NDB location allows to position the A/C on a final approach,totally useless when aid is at other end of the runway.A fly level approach(IMO)means plan to reach MDA/minima as soon as established inbound and continue at that level to MAPT to best utilise the available circling area.
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the force,it really sucks