- Tue Aug 08, 2017 2:46 pm
As Andreas says, instrument approaches are a big topic difficult to cover in a single forum post. However, as a very general overview to get you started:
An instrument approach procedure is a procedure designed to bring you from a position potentially in instrument meteorological conditions, i.e. in cloud, to a suitable height and position at which you can see the runway sufficiently to land on it. Generally such a procedure will make use of a ground-based radio navigation aid such as a VOR, NDB or Instrument Landing System (ILS), but GPS-based procedures are coming in to increasing use as well. VOR and NDB-based procedures are referred to as "non-precision approaches", because they consist of lateral tracking guidance only (and the pilot must interpret the chart to construct and fly a suitable descent profile). ILS approaches are known as "precision approaches" because they include vertical tracking guidance (by way of the glide slope).
In any case, the procedure will have been designed to ensure that you remain clear of terrain and obstructions provided you follow the procedure (both laterally and vertically) as published on the chart. Stapleford, however, does not have any published instrument approach procedures, so all arrivals and departures must be conducted visually. This means that you need to be able to see enough to fly a normal visual circuit to land. Further, Stapleford is located in Class G airspace below the London TMA: there is no Air Traffic Control service, only an Air/Ground Radio service to aid with deconfliction (but ultimately the radio operator can only tell you about the traffic they know about and not issue instructions or vectors etc).
The important thing to remember is that if you are IFR and/or in IMC you cannot descend below the minimum safe altitude for the leg you are flying (until of course, you can see sufficiently to maintain visual clearance from terrain and obstacles). The MSA may be shown directly in some flight planners, will be shown on instrument approach charts, or you may need to calculate it yourself by noting the elevation of the highest obstacle 5NM either side of your planned track and adding 1,000 ft.
If you descend to the MSA and you are in cloud and thus you cannot see the airfield sufficiently to fly a circuit to land, then you have a bit of a problem.
You could, of course, divert to another airfield with better visibility and/or an instrument approach procedure. Alternatively, you could fly an instrument approach procedure at a nearby aerodrome, descending with the procedure until such time as you are below the cloud and you can see sufficiently to then break off from the procedure and navigate visually to your destination and carry out a visual approach and landing.
Flying a VOR approach is simply a case of reading the chart and using the VOR (and, often, DME) instrumentation to fly the tracks depicted. As mentioned, because a VOR has no direct cockpit glideslope indication you will also need to follow the altitudes shown on the charts, taking care not to descend below the minimum altitudes specified for each segment of the procedure. However, as Andreas says, there is plenty of documentation online about this sort of thing and you might also consider signing up for a VATSIM Pilot Rating course with one of the Approved Training Organisations (ATOs) which will cover this and much more.