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goose101
15th Sep 2010, 13:28
Can anyone advise on BA's landing performance (weight limitation) on the
A318 iand EJ 190 into LCY for wet rwy? Given that it is a grooved rwy, I am wondering if this has been taken into account when calculating the figures, and if it is, was there any flight testing done for this?

Given the short length of LDA at LCY, I would assume it must be severely limited for Wet RWY operations if grooved rwy is not considered

Thanks in advance for any help.

towser
15th Sep 2010, 13:30
E190 can land in LCY at max landing weight on a wet rwy.

goose101
15th Sep 2010, 13:48
Thanks for the info re: ej190. I am calculating LW performance for a smaller biz jet. with a lower MAX LW etc, and it is very restricted, only way I believe this can be improved is by utilising the grooved rwy characteristics, is this the usual scenario for ops at LCY?

towser
15th Sep 2010, 14:58
Our performance figures state ' ..........calculated using wet grooved rwy performance data'. This actually allows us to accept a tail wind (all be it small) at max landing weight on both E170 and E190

Dani
15th Sep 2010, 18:40
I guess take off is more limiting than landing. During an RTO you have to accelerate to V1 and full stop again, not only to stop. And the weight is higher.

But I'm pretty sure those airlines have made their homework.

Dani

safetypee
16th Sep 2010, 01:15
You should review the proposed operation very carefully before attempting to ‘stretch’ wet landing performance at LCY.
The airport history was that the original ungrooved concrete runway had to be cleaned regularly when jet traffic increased; this tended to ‘polish’ the surface and reduce the surface friction.
The runway had to be grooved to restore an acceptable level of friction (airport requirements), but grooves do not necessarily make a poor runway good. Concrete is a relatively poor surface when compared with asphalt, depending on the surface texture etc, etc, thus pushing performance limits might be unwise.

IIRC the UK CAA has issued ‘advice’ on grooved runways – basically no alleviation for wet? It may have been a FODCOM; anyone have a reference?

Providing that your steep approach landing clearance does not change the distances, you still should consider that there is a tendency to land long from a steep glidepath. The fixed distance markers (or equivalent) must be respected.
Also, consider crosswinds on a wet runway. LCY has some interesting gust effects, which could complicate directional control that may require more distance.

goose101
16th Sep 2010, 12:57
Thanks for all the info, really helpful.

Re:Towser - do you know how the performance figures for grooved rwy were derived? Was it using flight testing?

is it the case that when wishing to make use of grooved rwy characteristics you must conduct flight tests to establish the data?

Thanks in advance again.

safetypee
16th Sep 2010, 13:34
This is what I recalled:-
“It is not sufficient for a runway to be considered, for performance purposes, as dry when it is wet solely on the basis that it is constructed with, for example, grooves or porous friction course pavement. Dry runway performance must only be used when the CAA has accepted in writing that the aeroplane can actually achieve the “effectively dry” braking action referred to in the EU-OPS definition.
However, there is currently no provision in the UK for notifying operators of runways having such surfaces, and the CAA is not aware of runways elsewhere that fully meet the “effectively dry” criterion.” (my bold)
Ref http://www.caa.co.uk/docs/33/FOD200903.pdf

Also see http://pilotlab.net/aircraft-manufacture/airbus/operations-on-grooved-runwa.pdf
N.B. this is dated 2006, so LCY probably not considered at that time; also that take-off was cleared but landing was not.
The acceptable test methods are on page 5.

IMHO, the requirement for a ‘specially prepared surface’ implies the need for regular maintenance and reporting; hence back to the CAA FODCOM.
Repeating the point, LCY is not the place to push the limits.

towser
16th Sep 2010, 13:42
I'm afraid I can't tell you how the figures were derived, Embraer did approval flights into LCY but don't think they had anything to do with landing performance per se I suspect they are derived from a computer model. We did have a discussion about whether a grooved rwy could ever be considered wet but didn't really get anywhere due to basically what safetypee says above. There are however many factors involved for instance the 190 can accept a higher tailwind than the 170 due , I'm told, to the tyres which have a much flatter profile on the 190 hence greater contact patch. You might be better trying to contact someone who has experience of operating you a/c type into LCY.