Menu Sign In Contact FAQ
Welcome to our forums

Approach plates that show OCA/OCH - are they safe?

Peter wrote:

I vaguely recall somebody developing an app for converting the OCH to MDH etc. However (and this was quite some years ago) I think he did a CFIT and is no longer around. One can do it using a calculation.

I think it was @Aeroplus who I believe is alive and well.

EGTK Oxford

He’s busy running safaris in Africa now AFAIK, but, no, it was someone before him. But maybe he didn’t publicise it much.

Shoreham EGKA, United Kingdom

That app (iOS app written in Xcode/Swift) is still around and is called AeroPlus IFR Minima. See:
It is available for free but would need an update as it is still based on the old EU-OPS specs, even though not a lot has changed since that time.
It does, for example, offer support for minima for APV approaches, but does not make the distinction between LNAV/VNAV and LPV approaches. At that time, these approaches were all very new. We even have an API that could share the data with others.

I am indeed a lot of time away in Afrika and wish I had more time to spend online on this forum. :-)

@Peter: the guy that did a CFIT in Italy indeed worked on this app together with me until this tragic accident.

Last Edited by AeroPlus at 12 Apr 19:02
EDLE, Netherlands

AnthonyQ wrote:

I know it’s hard to believe….but some countries actually have hills and mountains…

Ok, I guess some actually do. But I just browsed Norway AIP. Many airport have non-ILS approaches because the glideslope will not work near mountainous terrain. Out of the rest with ILS, most still seem to have OCH below 200.

Last Edited by huv at 12 Apr 21:45
EKRK, Denmark

The fact that most Cat I ILSs have a DH of 200’ and an RVR of 550m makes that point.

EGKB Biggin Hill

Airborne_Again wrote:

I wouldn’t be so sure. I’ve seen a Jeppesen copyright notice which expressly says that data is used by permission of the Australian CAA, but doesn’t mention any other country.

It is the copyright notice of Jeppview. It says in full:

Copyright (c) 1990-2012 Jeppesen Sanderson, Inc. Material from the Australian Aeronautical Information Publication has been used by agreement with Airservices Australia.

ESKC (Uppsala/Sundbro), Sweden

When I did my IMCR (now IR(R)) training in 2011, I was taught how to calculate the DH or MDH, including the special IMCR minima which I only realised much later, probably from a post by Timothy, are advisory. I still keep the flow chart in my IMC flying folder and use it whenever I need to calculate these values. Being a UK-only instrument pilot, I have only ever used UK AIP plates and never even knew that commercial providers do the sums for you. Well my instructor might have mentioned it but I never saw any reason to buy commercial plates when the UK AIP provides all the ones that I am allowed to use.

strip near EGGW

I would be surprised if many IR(R)-only pilots invest in Jepp. After all, there are not that many airfields in the UK with instrument approaches which are normally used by light aircraft, so getting to know the few you use is not much of a challenge. It is much more valuable for the pilot who flies to different destinations around Europe and the world, where consistency of presentation and quick reference to information becomes much more important.

On the IMCR minima thing, firstly remember that the 1500m flight visibility is hard law. You must not take off or land if the vis is lower.

Also, remember that the AIP recommended altitude minima are there for a very good reason, and most IR(R) holders are not trained or current enough to go lower.

The exception I have drawn people’s attention to is that if you have decided that, for your own purposes, an IMCR/IR(R) grants you the privileges you need and if:

  • You are trained to IR standards
  • You maintain your currency
  • You can consistently fly to system minima (not just after training)

Then there is nothing in law to stop you descending to system minima altitudes, but the default should still be to apply the AIP minima. It would be dreadful if the average IMCR/IR(R) were to go away with the idea that the recommended minima don’t apply to them.

EGKB Biggin Hill

Good advice as always Timothy. Being only an occasional instrument pilot I do indeed stick to IMCR limits.

strip near EGGW

Worryingly, I also come across some IR(R) holders who fail to understand minima calculations and seem to think 500/600’ is a blanket figure, oblivious to the terrain specific figures of the actual approach

Now retired from forums best wishes
Sign in to add your message

Back to Top