Non-precision approaches

I have started flying non-precision approaches now, this means flying a racetrack hold around either an NDB or a VOR beacon and correcting for wind while talking to Seville approach and looking at the approach plate, all at the same time.

Once ready for the approach I then have to descend to a minimum height specified on the approach plate and do my landing checks before turning towards the runway, contacting Seville again, then contacting Jerez and starting my decent towards the runway at a specific rate, whilst keeping the aircraft on track towards the runway (this is all done with screens up so I cannot see out of the windows by the way).  All of this happens in less than 1.5 minutes, so the work load is pretty high and demands a lot of concentration.


The non-precision approach is almost exactly what it says on the tin “not precise” and so even if we are amazingly accurate, it is still possible to be not lined up with the runway properly.  Following the needles from the beacon is therefore quite important because if you are not accurate on the needles, then you are definitely nowhere near lined up with the runway.  The idea of the non-precision approach is to descend to a height and distance from the runway where you should be able to see the runway, then adjust to make a visual approach.

So it is not the same as when you are on a British Airways flight into Heathrow and the plane follows an Instrument Landing System for vertical height and horizontal alignment, where the beacon and the needles are accurate to within 2m of your position.  The non-precision approach has only horizontal alignment, and that is alignment to a beacon that is about 6miles away from the runway and not (as is the case in Seville) necessarily even aligned with the runway.

The non-precision approaches are again making the flying feel more and more real, we are departing on SIDs and then heading out towards the beacon, holding, and then descending using either a STAR or a hold at the beacon.  All of this makes for quite busy radio chatter and very precise flying is required.  When it comes to the test, the vertical path tolerance is +50ft/-0ft.  This means I can be 50ft above (the aircraft can climb this much in about 2 seconds) or 0ft below, if I breach either of these then it is a fail on my instrument rating!  (Jerez VOR approach plate below)


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~ by globalste on September 19, 2011.

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