Why no BC (back course) approaches in Europe?

Malibuflyer wrote:

Because the reason for having ILS on just one side of the runway and not the other are typically not the cost for installing an additional set of ILS/LOC equipment but rather obstacle clearance, missed approach procedures, etc.

Not to forget prevailing winds! There is hardly a point installing an ILS on a runway which might have 2-3 days per year wind which would make its use necessary.

Airborne_Again wrote:

Many small airports have always had ILS just on one side of the runway, but now they also have LPV to the other side — and you’re saying the reason they didn’t have double ILSes in the first place was not cost?

Yes and no. I think that in the past, cost was an issue but also all the stuff mentioned by @Malibuflyer and also prevailing winds.

Also in the past, it was pretty rare that approaches would be done for political reasons, so they were designed to fit all the conditions the airport had: Obstacles, terrain, wind, e.t.c. as well as optimal traffic flow on larger airports. With mounting pressure on airports, that has changed and some runways did get approaches to satisfy local noise people or even due to restrictions imposed by neighboring countries: We’ve had this in Zurich and of course the infamouse ILS to Altenrhein which goes 100% against the prevailing winds because Austria denied installing an approach from the East.

LPV approaches are less expensive and also more flexible in this regard, so I suppose that is the main reason why now lesser used runways are getting one, but not only. In recent years political and other restrictions on airports may well make it desirable to split the traffic into portions to distribute the noise “fairly”. Given that the hurdles of creating a GPS based approach are considerably less, that is why they are done. I also think that GPS approaches can be constructed more flexibly than ILS ones with regard to terrains and other stuff which would make ILS approaches less useful or desirable.

Another factor is an increased demand on risk minimisation. In the 1980ties and 90ties non precision approaches were still something “acceptable” to people so BC, NDB, VOR approaches without vertical guidance onto lesser used runways or airports as well as circling approaches over less than optimal territory were the norm. After quite a few accidents, that perception has changed and approaches with vertical guidance became the standard rather than the exception. In ZRH for instance, the VOR approaches to runway 28 was replaced by an ILS following the crash of a Crossair RJ100. Salzburg for years had (still has I believe) a circling approach to it’s runway 34 but with GPS technology also has a GPS approach now.

Clearly also replacement of expensive ILS equipment with LPV will be the norm in the future as GPS/LPV provides better guidance anyhow, particularly at the final stages of the approach.

The BC approach will have as same minima as ILS circling anyway, so any obstacles OCH argument is rather moot

The huge advantage it will give is burning less fuel when you are inbound from non-ILS end correct side”, getting vectored to ILS-end and circling takes about 30min unless you cancel IFR and fly visual (nothing more disappointing than flying a whole 10DME arc or getting vectored 2×15nm extra when you pass overhead and you spot the runway)

Even when there is an LPV, I still ask for ILS then CTL or VFR when weather is nice

Peter wrote:

is a BC implemented with the normal LOC antenna (which AFAIK always radiates a lobe on the opposite bearing)

Yes. That is the whole idea of it. You use the back lobe of the LOC.

Ibra wrote:

The BC approach will have as same minima as ILS circling anyway, so any obstacles OCH argument is rather moot

The missed approach for the BC and the ILS-Circling look completely different so there is very obviously a lot more obstacle clearance considerations to be done when adding an approach from the other side of the field …

Ibra wrote:

Even when there is an LPV, I still ask for ILS then CTL

Any particular reason? LPV with full vertical guidance is pretty much the same as an ILS.

Ibra wrote:

The BC approach will have as same minima as ILS circling anyway, so any obstacles OCH argument is rather moot

I thought that argument was more about why there is no ILS on that side. Quite a few runways simply have no possibility to reasonably fit an ILS because of obstacles which prevent it’s use down to less than non precision approaches anyway.

(E.g runway 32 at ZRH as well as 10, both of which would be “nice” to have an approach to, don’t work because of hills and obstacles on final which would trigger EGPS warnings and simply are not according to OC limits. They actually did install a localizer on 32 and tried with a loc only approach, but threw the idea away. Either you’d have to employ GS angles which most planes can’t do anyway or make the minimas so high that you reach them at 4-5 NM final, which makes the whole thing useless. )

However, that attitude has changed following some rather bad accidents, these days vertical guidance is definitly preferred over non precision approaches wherever possible, even if minima are higher due to obstacles. Most of the accidents on npas did not happen in that area where you’d have to continue visually after the approach but continuing descent at an intermediate step down and hitting the ground. ZRH has got 2 ILS approaches (28 and 34) which are with higher minimas or CAT I due to obstacles rather than the technical possibility to make them proper ILS or CAT II/III respectively.

Mooney_Driver wrote:

I thought that argument was more about why there is no ILS on that side. Quite a few runways simply have no possibility to reasonably fit an ILS because of obstacles which prevent it’s use down to less than non precision approaches anyway.

Salzburg runway 34 is a great example for this as well: You are barely established on the final approach course before the MAP. An ILS would be completely useless.

Mooney_Driver wrote:

Any particular reason? LPV with full vertical guidance is pretty much the same as an ILS

Fuel saving when weather is nice

Malibuflyer wrote:

The missed approach for the BC and the ILS-Circling look completely different so there is very obviously a lot more obstacle clearance considerations to be done when adding an approach from the other side of the field …

Good point on takeoff & missed from non-ILS end that won’t be factored in circling design

Malibuflyer wrote:

Salzburg runway 34 is a great example for this as well: You are barely established on the final approach course before the MAP. An ILS would be completely useless.

Exactly, yes. Was the first one which came to mind.

I recall that in the 1990ties they were experimenting with a “Lugano Style” IlS from that side and some enterprising Tyrolean pilots sometimes actually used the back course when coming from the south, but while that works on a truck like the Dash 7 or (barely) with the Fokker 70, it was discarded. I think the glide would have had to be something like 7 degrees. (Lugano if I remember right was 6).