(Updated in November 2022 due to revisions of part-NCO effective October 30, 2022.)
With GPS it is easy to add an instrument approach to virtually any runway. (At least as long as the obstacle situation is reasonable). Still, we have not – at least not in Sweden – seen any such approaches to airports that didn’t already have an instrument approach. Some GPS approaches to airports without previous instrument approaches have been in the works for quite a while, but never seem to be ready.
What seems not to be well known is that the regulations permit you to use “do it yourself” (DIY) – i.e. unoffical and unapproved – instrument approache procedures. Designing and using such as approach does put a lot of responsibility on the individual pilot, but given that the obstacle situation is uncomplicated and the minima set high enough, a DIY approach is arguably safer than making a cloud break at an instrument airport some distance away and then continuing to the destination in marginal VFR conditions.
So, what do the regulations actually say about this? If we first look at the Rules of the Air (SERA), we have the well-known minimum height for IFR of 1000′ feet above obstacles. However, according to SERA.3105 you can descend below that height when “necessary” for landing. SERA says nothing about having to use a published or approved procedure for landing.
Next, let’s have a look at the ops rules. The relevant rule is NCO.OP.115(a).
NCO.OP.115 Departure and approach procedures – aeroplanes and helicopters
(a) The pilot-in-command shall use the departure and approach procedures established by the State of the aerodrome, if such procedures have been published for the runway or FATO to be used.
Note the “if”… This implies that when no procedure “established by the State” has been published then you are free to use whatever procedure you want.
The AMC to this rule makes this clear
AMC1 NCO.OP.115 Departure and approach procedures — aeroplanes and helicopters
ARRIVALS AND DEPARTURES UNDER IFR WHERE NO INSTRUMENT FLIGHT PROCEDURES ARE PUBLISHED
When arriving or departing under IFR to/from an aerodrome or operating site with no published instrument flight procedure, the pilot-in-command should ensure that sufficient obstacle clearance is available for safe operation. This may be achieved, for example, by climbing or descending visually when below a minimum altitude at which obstacle clearance is known to exist. […]
You can also compare the rule to the corresponding rule for Commercial Air Traffic, CAT.OP.MPA.125.
CAT.OP.MPA.125 Instrument departure and approach procedures
(a) The operator shall ensure that instrument departure and approach procedures established by the State of the aerodrome are used.
The difference in wording makes no sense unless the regulator really intended that non-commercial operations may use procedures other than those established by the state. Although this may seem revolutionary, there are precedents. At least in the United Kingdom DIY procedures have always been legal even before part-NCO. Officials of some national aviation authorities may not like this, but that doesn’t mean it’s illegal.
Using a DIY procedure in controlled airspace is probably not possible, though. ATC don’t know about it and (at least in Sweden) they are not allowed to clear you below the minimum vector altitude.
So should you use a DIY approach? If you are familiar with the area and have carefully checked for obstacles, why not? It is important, though, to make sensible and conservative minima and stick to them. Remember that NCO.OP.110 requires you to determine minima based on a number of factors. The minima aren’t any less important just because you decided on them yourself. Don’t forget the visibility minima! More likely than not there will be no approach lights and no high-intensity runway lights. Visibility is the real killer in marginal weather. Also, don’t forget the missed approach procedure – know how to safely get back to enroute altitudes if you don’t see the runway. Finally, you should flight check your procedure in VMC before trying it in anger. But perhaps that goes without saying?
You can read more about safety assessment of GPS-based approaches to non-instrument runways in this document prepared by by the European Union Agency for the Space Programme (EUSPA) supported by European Aviation Safety Agency (EASA) and others.
Timothy Nathan of PPL/IR Europe has written a set of guidelines for DIY approaches. It was proposal to the British CAA which was not adopted, but that doesn’t make it any less relevant. Timothy retains all rights to the contents of that document.
After Timothy’s paper was written, Garmin introduced a feature in its GTN650/750 series of navigators where you can get a 3° ILS-like glidepath to any runway on every airport in its database (as long as enough information about the runway has been published). This feature is intended as an aid to visual approaches but it also makes it particularly easy to fly a DIY instrument approach – at least as long as the 3° glidepath has sufficient obstacle clearance.