A genuine query for experts?

Elmer Blooker

Can anyone tell me why flights after 11pm approaching Dublin Airport fly so low over residential areas in north Dublin but don't during the daytime? They seem to be coming in at about one per minute and are very very loud! In fact almost frightening! (At the moment its like Berlin 1948!!)
During the daytime flights seem to approach the airport from the east from the Howth and Ireland's Eye direction but not after 11pm? Its been something I've wondering about for some time and I thought this would be a good place to ask.

ED E

(Not an expert)

Its night works AFAIK. They've closed the other runway to do maintenance or upgrades so the approach paths change.

Runways get a hell of a lot of wear and tear so keeping them in working order is a large job. See documentaries on Heathrow for some examples of such.

robyntmorton

I'd need to check the NOTAMS, but the main runway is regularly closed for works overnights. This leaves the crosswind runway 16/34 for the late flights. I get them further out in south county Dublin at the start of the approach.

plodder

I think there is some maintenance work being done on the main runway at night times. So, the alternative 16/34 runway is used at night. I live under the other side of it, where the approach is over rural North county Dublin. Can't say it bothers me, though they may be a little higher when they pass over my house.

robyntmorton

Indeed there is a NOTAM noting closure of 10/28 overnights at the moment. Work being done on the surface.

irishfire

Non aviation expert, but I do know that Lagan are resurfacing the main runway in sections at night. Was on a PSCS CPC course last year and I met 2 managers that were training up for the works. Something like 50 meters every night afaik?

Irish Steve

What's unusual about this evening is that due to the prevailing winds, they are landing on runway 34, which would be the least used runway of the 4 available, the normal use of that runway pair would be for landings to come in from the North, but with the wind at 300/08Kts, the most in to wind runway that's available overnight is 34, so the approach profile comes in over Ringsend.

smurfjed

Elmer, a landing aircraft will usually descent at a rate of around 300 feet per nautical mile, so with aircraft landing on RWY34 due to works and winds, they will pass Fairview around 1000 feet, Beaumont around 600 feet and Santry around 300 feet. 
Modern aircraft are a lot quieter than the older Stage 2 Noise Certified aircraft.

trellheim

Can I add to this, why are dual runways not used at the moment during the morning peak ? I recall some time ago that 28 and 34 were both in use simultaneously but this seems to have stopped, As I frequently sit waiting my turn for 28 on a weekly/daily basis in the queue , I'd be interested in the reasoning here ,

is that pilots request or tower direction ? so if a pilot asked for 34 would he get it ?

The Veteran

trellheim wrote: »

Can I add to this, why are dual runways not used at the moment during the morning peak ? I recall some time ago that 28 and 34 were both in use simultaneously but this seems to have stopped, As I frequently sit waiting my turn for 28 on a weekly/daily basis in the queue , I'd be interested in the reasoning here ,

is that pilots request or tower direction ? so if a pilot asked for 34 would he get it ?

Ryanair wingtip collision at the turn for line-up when in dual operation has put pay to dual ops

EchoIndia

trellheim wrote: »

Can I add to this, why are dual runways not used at the moment during the morning peak ? I recall some time ago that 28 and 34 were both in use simultaneously but this seems to have stopped, As I frequently sit waiting my turn for 28 on a weekly/daily basis in the queue , I'd be interested in the reasoning here ,

is that pilots request or tower direction ? so if a pilot asked for 34 would he get it ?

Dual runway operations still occur up to 0800 local time, depending on ATC and other factors.

trellheim

Dual runway operations still occur up to 0800 local time, depending on ATC and other factors.

I'm through nearly twice a week on first wave and - not someone who works there, but I haven't seen it in donkeys ages

Would a pilot get 34 if they asked for it just to expedite matters or is the answer "thats not how that works" ... curious ( assuming weather allows for it OK and all that )

PS thanks for the answers folks.

Captain_Crash

trellheim wrote: »

I'm through nearly twice a week on first wave and - not someone who works there, but I haven't seen it in donkeys ages

I see dual ops most mornings when I'm driving past on the way to work just after 7am.

Captain_Crash

smurfjed wrote: »

Santry around 300 feet

While your vastly more qualified than me to answer, I would imagine 300ft over Santry to be a bit low for an approach into 34 no?

The plate for 34 has the height at 650ft 1nm from the rwy threshold: http://iaip.iaa.ie/iaip/Published%20Files/AIP%20Files/AD/Chart%20Files/EIDW/EI_AD_2_EIDW_24-33.1_en.pdf

martinsvi

Captain_Crash wrote: »

While your vastly more qualified than me to answer, I would imagine 300ft over Santry to be a bit low for an approach into 34 no?

The plate for 34 has the height at 650ft 1nm from the rwy threshold: http://iaip.iaa.ie/iaip/Published%20Files/AIP%20Files/AD/Chart%20Files/EIDW/EI_AD_2_EIDW_24-33.1_en.pdf

650ft is not height, it's altitude according to QNH (sea level). Height (above airfield level) is given in brackets as 448ft

Captain_Crash

martinsvi wrote: »

650ft is not height, it's altitude according to QNH (sea level). Height (above airfield level) is given in brackets as 448ft

Yes... my mistake, Ive actually just kicked myself in the back of the head with that:P I was rushing the post and didn't stop to check

But the original point is still valid I guess?

martinsvi

Captain_Crash wrote: »

But the original point is still valid I guess?

it depends whether you treat smurfs comment as a statement of fact or more like a simple explanation in layman's terms ..

trellheim

I see dual ops most mornings when I'm driving past on the way to work just after 7am.

Thanks must be just me , I'm normally stuck waiting in the queue of jets at 0630 and havent seen it in ages

Captain_Crash

martinsvi wrote: »

it depends whether you treat smurfs comment as a statement of fact or more like a simple explanation in layman's terms ..

Well I certainly wouldn't be questioning smurfs knowledge on the matter so I imagine its a simple explanation in layman's terms

Irish Steve

Re Dual Ops,

My understanding, which may not now be completely accurate or up to date, as a result of 2 wing tip collision issues, dual ops on 28/34 are now more aligned to using 28 for the jets, and letting the turbo props go from 34, but that may have been changed again. The issue is clearances on the access routes to the 2 runways, especially with the 737-800's, if they stop short of the stop line, that can result in insufficient clearance for other aircraft. One of the routes was closed for a time after the second incident, there may have been some alignment changes to try and mitigate the problem.

Another factor is that depending on the destination after departure, there can be flow limits into UK airspace, so using 2 runways for departures may not actually help the flow rate, if they're all heading out in the same basic direction, there may be no advantage to be gained from using 34.

Lapmo_Dancer

28 for southerly departures - Pesit, Bepan etc and 34 for northerly - Liffy, Rotev etc unless 28 is required for performance reasons.

There has been a south easterly airflow recently precluding the use of 34 for many as 34 is quite limiting with a tailwind.

A lot of Stobart's first wave are heading north - EDI, GLA, NCL.

trellheim

Really appreciate this, it gives some context.

Ta

smurfjed

Sometimes I do try to keep things simple:):) But for those with a deeper interest, this is the RNAV approach chart, touchdown elevation is 202 feet, have a look at the box in the middle that gives distances to touchdown with the associated altitude.