Where have you been? What have you seen?
#1850335
I went to Sibson today for the first time. The main runway 06/24 is, according to the plate in Sky Demon, 935m long, and indeed measuring the strip in Google Earth, so it is.

However, the overlay on the diagram on their web site bears virtually no relation to reality, and I'd highly recommend looking at it in Google Earth, and noting that the bit that actually looks like the runway (with the numbers at each end, and the corner markings), is only about 200m long.

I'd also recommend paying closer attention to the phone briefing than I did, which, on 06, was to land as soon as possible, subject to clearing the trees at the threshold.

I was thrown by the fact that the runway bore so little relation to the diagram, and also by not having had a chance to look at the strip from the overhead (there's no deadside due to the parachuting on the north side of the field).

The markings (as on Google Earth but a lot whiter) are very fresh, so it was easy to fall into the trap of assuming that they've been put there for a reason, rather than as a trap to confuse the hard of thinking such as I.

Anyway, I avoided the undershoot area and touched down good and slow, pretty much on the numbers. I used up about 300m in all, despite the fact that the strip goes quite steeply downhill after the first 150-200m.

If I'd arrived in the flare too fast, it could have been a lot more exciting - even as it was, the downhill bit which was obvious at touchdown was sufficiently attention-getting that I was on the brakes very early.

Taking off I used the whole length, and indeed the surface all the way along the undershoot is perfectly ok.

So if you go there, ignore the markings, and land well before the 06 numbers.

Other than that, it's a nice field. Sausage egg and bacon bap: approved.
tr7v8, rdfb, Rob P and 2 others liked this
#1850508
Thank you. I plan a trip this month if I get a chance. I've not been there before as I've always been a bit nervous of it, particularly since a fatal accident there some years ago, involving an aircraft of a type similar to the one I now fly.

I love almost everything about Skydemon, but pay a subscription for the Pooley's plates. If you look at the Pooley's plate for Sibson it shows the LDA and the TORA which I think are more meaningful than the actual physical length of the strip.

I think the displaced thresholds are there for a purpose, and if I recall correctly, they are there because of the pylons at one end and trees at another.

I have a memory of finding leaves caught in my undercarriage trying to land short over trees, (at Canterbury though, not Sibson. That was an interesting strip if anyone remembers it).
#1850622
Dodo wrote:Thank you. I plan a trip this month if I get a chance. I've not been there before as I've always been a bit nervous of it, particularly since a fatal accident there some years ago, involving an aircraft of a type similar to the one I now fly.

Which is? Caused by?

I love almost everything about Skydemon, but pay a subscription for the Pooley's plates. If you look at the Pooley's plate for Sibson it shows the LDA and the TORA which I think are more meaningful than the actual physical length of the strip.

I only have a 1997 Pooleys, What does the current one quote for these?

I think the displaced thresholds are there for a purpose, and if I recall correctly, they are there because of the pylons at one end and trees at another.

Indeed. The trees at the western end are pretty tall. But unless you insist on flying a 3 degree approach, the marked threshold is a lot further into the strip than it needs to be. If I'd been a bit more switched on and confident of the surface, I could have landed at least 200m earlier, maybe more, and I certainly would next time.

There are power lines at the eastern end too, to avoid. It didn't look difficult.

Perhaps not a destination for a first post-licence flight, however.
#1850629
Posts crossed..

Pooley's sub is £25 as a skydemon add on. Unfortunately it is yearly, so you can't keep it like the old paper one, but it is georeferenced.

I just realised you meant what does Pooley's quote for LDA and TORA, not a cost quote for a Skydemon Pooleys add on, sorry.
so
LDA is 468m on 06 and 676m on 24. TORA is the other way round.

I fly a Bolkow 208, though have a share in an Archer too. The 208 accident is here.
https://assets.publishing.service.gov.uk/media/5422ee93e5274a131400020f/Bolkow_208C_Junior_D-EGFU_09-12.pdf is the link. The key wording runs...

The aircraft was on final approach to land at Sibson
Airfield when it struck the uppermost cable of a set of
power transmission lines situated approximately 0.5 nm
from the airfield. The runway in use had a significantly
displaced threshold to provide aircraft on approach
with adequate clearance from the transmission lines.
Evidence suggested that the pilot made an approach to
the start of the prepared runway surface, rather than the
displaced threshold.

I agree prob not ideal for first post licence airfield but this would be my 200th plus. Doesn't stop me being nervous about it though!
#1850640
Dodo wrote:LDA is 468m on 06 and 676m on 24. TORA is the other way round.

If they count the 468 from the marked threshold (which, measuring on Google Earth they clearly do), then I think that is highly misleading. East of the 24 numbers it goes distinctly downhill, and if you still have any speed on by then, your brakes had better be good.

I would aim to approach at short field speed, and land 200m before the 06 numbers if they're on easterlies. This will make the whole thing completely drama-free. The surface is good all the way along.

If you can sideslip to get excess height off as you come over the trees all the better.

I agree prob not ideal for first post licence airfield but this would be my 200th plus. Doesn't stop me being nervous about it though!

A bit of nerves isn't a bad thing. Focuses the mind :)
#1850647
Interesting how Skydemon shows this and probably a lesson to be learnt in how to interpret their charts:
Image

So whereas it gives the overall 'runway' length as 935m, they also very clearly show the displaced thresholds.
Skydemon does not show LDA or TORA.
Seeing those shown like that it should have begged the question "why?"

The airfield website itself is sadly no clearer, although it does help if you know what to look for:
Image

Rather strangely, the website doesn't appear to list TORA/LDA and the bullet points below this picture do not necessarily make things as clear as they should be, so probably lessons to be learnt all around... To make it worse, the overlaid satellite image shows an different runway configuration and I cannot match the start of the box purporting to show '06 arrivals' on this diagram to the actual marking on that (old) google image.

Currently on Google maps, it shows this:
Image

which is quite close to the Skydemon diagram and, by the sounds of it, quite close to your experience, but far away from the diagram on the website.

It looks to me like the Skydemon diagram is actually quite good, but that there is a potential for misunderstanding that the 'runway length' is not LDA or TORA. We all know this of course but normally the displaced thresholds are not half way up the runway... So we should be aware when we see such a diagram that we may need to find out more.

If my understanding is correct then I have more beef with the airfield website, which probably could emphasise that slightly more, especially if there have been accidents for similar reasons in the past, and at least (i) provide LDA and TORA and (ii) update their overhead image to be current layout and (iii) review the diagram which does not appear to correspond to actuality.

Anyway... thanks for the heads up :thumleft:
#1850661
Morten wrote:... To make it worse, the overlaid satellite image shows an different runway configuration and I cannot match the start of the box purporting to show '06 arrivals' on this diagram to the actual marking on that (old) google image ....

If my understanding is correct then I have more beef with the airfield website,

Indeed, as I said in my OP:

TopCat wrote:However, the overlay on the diagram on their web site bears virtually no relation to reality, and I'd highly recommend looking at it in Google Earth, and noting that the bit that actually looks like the runway (with the numbers at each end, and the corner markings), is only about 200m long.


The SD map and the Google image that you've posted are a good representation of reality.

The arrows and runway markers have been repainted since that image as they're a lot brighter.
#1850871
Dodo wrote:Pooley's sub is £25 as a skydemon add on.

That's not a bad deal! I pay £70 for a corresponding add-on for Sweden. It's a 3pp add-on sold through SD, so no complaints. And the customer base for Swedish plates is obviously much smaller, so a higher price is not surprising.
#1851386
I learnt to fly at Sibson.
The runway was originally 07/25 and it stopped where the 24 numbers are now - there was a hedge. No one ran into the hedge as far as I recall during my training while using 07 but it did promote good landing technique, which has served me well in my flying.

The extension was done mainly for the Lett parachute aircraft when taking off, but due to the slope on the extension you can't see the rest of the runway, so we didn't bother as the gain in speed up the slope was of minimal use.

I suspect the trees are taller now but even in 90's we sometimes executed a very early left turn if climb was not adequate. :thumright: