PPRuNe Forums - View Single Post - NDB approach - Do you ADD an allowance for "sink" ?
Old 6th Jun 2001, 04:54
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Roadtrip
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Circling approaches at wx mins in heavy jets is really not very smart, especially considering the frequency that heavy jet pilots get to practice it -- i.e. almost never. Part 121 heavy jet carriers don't allow circling approaches.

That being said, on non-precision approaches, namly VORs or Localizers, consideration of technique should depend on what the weather conditions are.

If the visibility is poor with a poorly defined ceiling, then a "stabilized" approach probably gives the pilot the best chance of putting the aircraft into a position to execute a normal landing -- i.e. the aircraft arrives at the VDP (or NDP) on speed, in a stabilized descent. The relative deck angle is 3 deg lower than would be on a "dive and drive" approach thus giving the pilots a better downward vision angle for visually acquiring the runway in poor vis conditions. The descent rate is already established. All that remains is to laterally position the aircraft.

If a thick ceiling is well defined and above MDA, and visibility good below, then a "dive and drive" technique gets the pilot visual earlier, allowing a better line up and plenty of time for preparation for descent at the VDP.

It should be noted, however, you should never go below MDA unless the aircraft is in a position to execute a normal glidepath and landing.