New style TDZ markers in the UK

[Doors to Automatic]

Apologies if this has been asked before but I just wondered why the aiming point markers on some UK runways have been changed recently?

I am talking about the zig-zag style markers unique to the UK, which have been replaced by European style solid blocks.

So far I have seen them at Belfast (Int) and on the newly positioned touchdown zone on runway 33 at Birmingham - although I am guessing they will also be appearing on the 15 end when the resurfacing gets there in April.

Any insight would be interesting!

[Sir George Cayley]

If you check out ICAO Annex 14 Vol 1 Aerodromes and compare the TDZ markings there with the ones in CAP168 Aerodrome Licensing you can see the difference immediately.

The UK now falls under EASA for airport regulation and their preferred reference is ICAO not CAA.

Hence airports can now propose an Annex 14 solution even if that is not contained in CAP168.

I have to say well spotted D2A - ever thought of being an aerodrome inspector?

[Doors to Automatic]

Thank you Sir George, and thank you for the explanation. Do you know why the UK adopted the zig zag markers in the first place? We seem to be the only country in the world to have them!

[chevvron]

The zigzag markings are actually called 'aiming point' markings and are positioned within the 'touchdown zone'.

[safetypee]

Chev, I presume that the aiming point refers to the point of touchdown. If not, using the markings as a flight path angle aiming point might conflict with PAPI and also tend to move the actual touchdown point further into the runway. Either way it appears there is need for an official explanation and guidance.

[safetypee]

Thanks for the ref LFAJ. However, the text in my copy (4th Ed) does not answer my questions, nor clarify what the markings actual consist of – not a zig zag in any of the diagrams.

Could it be assumed that the zigzags are a replacement for existing aiming point markings (#2) - there is less white paint than previously (Annex 14, fig 5.5), which are a nominal 400m from the threshold on a long runway?
If so, we have always lived with the disparity in aiming / touchdown, PAPI/ILS, etc, where the markings might not have been interpreted / used in any particular way.

[chevvron]

The aiming point markings are usually (but not always) the point where both ILS and PAPI glidepath intercept the runway surface. The glidepath passes over the runway threshold by a minimum of 50ft. (called MEHT)

[kdhurst380]

I appreciate that this is now an old topic, but I flew as a passenger into MAN on Monday, it would appear that compliance with the ICAO regs is now actively encouraged/enforced, as at least on 23R, they've gone to the trouble of blacking out the zig-zag markers and painting over with the solid European style bars.

It's a bit nerdy really, but I'll miss the zig-zags, we've had them for a very long time! I suppose EASA wants everyone to be the same.

[kdhurst380]

That is a very long document... what did the ICAO ever do wrong?!

In the UK, we essentially seem to have done what the Irish have, their runways are marked with the single block fixed distance markers and the slightly bigger block aiming point marker. The French, Spanish and Italians don't follow the same logic, which multi-stripe distance markers. What will be the common standard?!

It raises the age old question... who pays for it? Well, obviously not the rule makers! The airports will pass it down to the airlines/consumers who buy stuff in the terminals, just like how the airlines pass the costs of EU261 down to us lowly passengers.

Bravo. We are all one Europe, and all that.

(I'm not anti EU, by the way, it just seems stupid that everyone else in the world is more than happy with ICAO, then the Europeans decide it's not good enough... just like that, it's as if they've got nothing better to do).

[Musket90]

The reasons for UK CAA's differences to the ICAO standard for runway aiming point markings is given in the UK AIP GEN Section, 1.7-35:

Quote
a. The shape of the marking means that 1/3rd of it is outside the centre 3rd of the runway and is therefore less prone to rubber contamination.
b. The marking is more easily identifiable as it differs from the TDZ markings.
c. It provides enhanced visual cues for the angle of approach.

EASA requires the same as ICAO so not sure if UK CAA will stick with the difference. Although some already have, I don't think UK airports need to suddenly change markings to comply with EASA/ICAO, particularly if there are no safety implications in retaining the UK markings.

[chevvron]

I dare say as they get re-surfaced they will re-paint the markings to EASA requirements; no point re-painting before then.

[Musket90]

I'm sure many airports for many different reasons cannot meet the EASA design requirements just like many cannot meet ICAO and CAA standards. That's why EASA has such things called "Special Conditions", "Deviation and Action Documents (DAAD), "Equivalent Level of Safety (ELOS), "Alternative Means of Compliance (ALTMOC) etc. These provide a means for an airport not able to meet design requirements to provide the authority with safety assurance detailing the mitigating measures.

As for CAA vs EASA runway aiming point markings, that I would suggest is not the highest of priorities when considering runway safety issues.

[kdhurst380]

Although as per my original post, MAN have done, on the 23R end and it's within the last couple of months. The old markings have been painted over in black and replaced with the solid blocks, that's why I posted. I'm curious to see if they've taken it upon themselves or whether EASA have suddenly decided everyone needs to be doing the same thing.