Correct length for new Dublin runway , a matter of opinion?

dohouch

I might learn something here. :rolleyes:

Apparently the pilots want 3,600 meters, but the airport is building 3,100 meters .

Surely the correct length for a runway is not a matter of opinion, but a matter of physics.

I suppose coming to a forum for consensus of opinion is a bit hopeless, but I want to hear the some explanations. I did try to search the main thread here

Dublin Airport New Runway/Infrastructure

but no luck.

Doylers

dohouch wrote: »

I might learn something here.  :rolleyes:

Apparently the pilots want 3,600 meters, but the airport is building 3,100 meters .

Surely the correct length for a runway is not a matter of opinion, but a matter of physics.

I suppose coming to a forum for consensus of opinion is a bit hopeless, but I want to hear the some explanations.  I did try to search the main thread here

Dublin Airport New Runway/Infrastructure

but no luck.

It depends on the plane size you want to accommodate really. A bad explanation is imagine you need 1500 to get in the air, you'll need in or around the same distance to stop so you need 3000. Then plus a few % for rain and good luck. IMO i'd wonder why not just go large as economically possible even if we can't handle the likes of 380s for a terminal standpoint.

Fattes

dohouch wrote: »

I might learn something here. :rolleyes:

Apparently the pilots want 3,600 meters, but the airport is building 3,100 meters .

Surely the correct length for a runway is not a matter of opinion, but a matter of physics.

I suppose coming to a forum for consensus of opinion is a bit hopeless, but I want to hear the some explanations. I did try to search the main thread here but no luck.

All to do with Maximum Take off weight (MTOW) So for example the Cathy A350 Needs 3,600m to take off at its capacity. I think the difference between the two lengths is approx 20 tons for an A350.

It all comes down to where you see Dublins future markets. The extra length would be great for Asian markets, but will make very little difference to US routes. May also make direct flights to places like Oz in the future possible with new airframes and technical advances.

However the inverse could be true new airframes, tech and engines may make the runway adequate in future.

All in all probably makes Fup all difference

Nijmegen

The new runway has been hanging around for so long in planning (it was approved in its current form in 2007) that the "ideal" has probably shifted a few times based on market requirements. There was a story floating around here that DAA wanted to build it longer when the project was reactivated post recession, but the hassle of going back to planning was deemed to outweigh the speculative future benefit.

The main thing a longer runway gives you is flexibility in the future towards the types of aircraft and routes you might expect to see. 3,100 meters is sufficient for what Dublin uses today, but then there's a chicken and egg situation. The only real downside to a longer runway outside planning is that it might be a wasteful expenditure of capital to go the extra few hundred meters, but then when T2 opened we were all told it too was a giant waste of money...

goingnowhere

3100m is 400m more than current and given Dublin's elevation and prevailing temperature this should be sufficient. I've seen EI get A330's to the West Coast off 16 so unless you are at MTOW the length isn't an issue.

We have flights to LA, Hong Kong so where are we missing because 28 is too short?

The warmer and higher you are the more length you need, so the Gulf region you see a lot of 4000m

Pilots (and airlines) would prefer longer, derated take offs, better stopping margin

basill

Its usually the tailwinds and runway state (ie: wet or snow) which scupper the widebodies off any Dublin runway. I just hope whatever runway length they decide on that they leave enough space at either end to extend it in the future should the need arise. In other words have some proper planning for once.

Whats the latest plan for dual/parallel operations? Last I heard the current runway (28L) would be closing for resurfacing once the new one was opened so there will be little good news for airlines unless the plan has a load of intersection departure points and sin bins for people on slots to avoid the current carpark around the airport. Also heard that there was no plan for parallel operations.

Cookiemunster

basill wrote: »

Last I heard the current runway (28L) would be closing for resurfacing once the new one was opened so there will be little good news for airlines unless the plan has a load of intersection departure points and sin bins for people on slots to avoid the current carpark around the airport. Also heard that there was no plan for parallel operations.

The current runway was resurfaced in sections overnight over the course of 18 months. I think it was finished in April.

goingnowhere

Dual ops are what is planned, 28R for take offs? 28L for landing? makes the most sense given the volume of flights that turn right towards LIFFY

There is talk of extending the current 28 also

dohouch

All thanks to @rover:
The key question is this 'Is a 3600m runway essential for long haul or is it a nice-to-have?' If DUB already has commercially viable non-stop service to LAX and HKG off its current 2637m runway then a 3110m has got be a big improvement. MAN has at best 3200m (23L) with similar long sectors to DUB operating viably also from 23R (2897m). Additional runway length comes at a cost of tens of millions of Euros which has to be funded through airport charges and is of real value only on a few occasions each year. I have done Performance A training and I know all about flex thrust and variable V1 figures, but airports have to make commercially sound investment decisions. Runways much longer than 3000m are rarely needed with a low airport elevation and a Northern European climate.

Chris_5339762

The crosswinds anyway (depending on what actually happens with 16/34, I haven't seen a firm answer on whether it'll be kept or scrapped) will be a bigger deal than runway length.

HTCOne

An issue is 3,100m isn’t long enough for the heaviest jets going long distance, particularly the big cargo boys like 77L, 747s etc.

As has already been stated, longer runways allow intersection takeoffs which improve efficiency by upping the number of possible movements per hour. You can let the narrowbody on 1,000m down the runway and get them airborne while the heavy they were taxiing behind is still on it’s way to the furthest holding point.

It’s also safer, results in less delays (less go arounds if landing a bit long) and results in less flight cancellations, as tech issues on the MEL are less likely to result in the aircraft being unable to depart with more tarmac to spare

dohouch

I like this additional info too, which gives more reason why pilots would like longer

Originally Posted by waffler View Post
You are obviously not a pilot, so here’s some information for you.
At the moment, most long haul aircraft departing Dublin this summer cannot land safely back in Dublin if they have a serious problem after takeoff because of the runway length.
The longer the runway the safer an immediate return to landing because of the faster speeds on landing in most emergencies.
The longer runway means that the engines don’t have to produce full power on takeoff thus preserving the engine life and reducing the yaw produced by an engine failure.
a longer runway means no restrictions on passangers and freight carried, thus making the flight cheaper for the airlines.
If Dublin is serious about being a hub and creating more jobs for Irish pilots and other workers it needs the right infrastructure.
who remembers the M50 extra lane debacle.
So knowing this now, you may understand why IALPA seeks the longest runway it can get.

kub

This country is not known for adequate forward thinking in regard to infrastructure, mind you for forward thinking full stop.


Some bean counter will simply look at numbers and go for the cheapest option here no doubt, without considering the implications like the future cost of extending the new runway.


Dublin is the country's principal airport, it should have facilities and infrastructure as good as or if not better than other European airports.

smurfjed

At the moment, most long haul aircraft departing Dublin this summer cannot land safely back in Dublin if they have a serious problem after takeoff because of the runway length.

Why not? If they can takeoff on it, they can land on it!

a longer runway means no restrictions on passangers and freight carried, thus making the flight cheaper for the airlines.

This wouldn't make it cheaper, but it would increase the possible revenue associated with the flight.

Did this really come from IALPA?

goingnowhere

Most planes would be overweight so would need to burn off fuel or dump before coming back.


Its all down to numbers

A330-300 HGW
A350-900 Cathay
B777-300ER Emirates

Assuming a calm, dry day, 15C whats the required runway length at MTOW?


Dusseldorf Airport in Germany (which the DAA owns a chunk of) runway is 3000m and has daily A380 service and Eurowings just moved its entire long haul ops from Koln/Bonn with its almost 4km long runway and 24 hour ops so they don't seem worried at all with 3000.

smurfjed

Most planes would be overweight so would need to burn off fuel or dump before coming back.

Don't confuse desire with need. (FAA regulations )
§25.1001   Fuel jettisoning system.
(a) A fuel jettisoning system must be installed on each airplane unless it is shown that the airplane meets the climb requirements of §§25.119 and 25.121(d) at maximum takeoff weight, less the actual or computed weight of fuel necessary for a 15-minute flight comprised of a takeoff, go-around, and landing at the airport of departure with the airplane configuration, speed, power, and thrust the same as that used in meeting the applicable takeoff, approach, and landing climb performance requirements of this part.
(b) If a fuel jettisoning system is required it must be capable of jettisoning enough fuel within 15 minutes, starting with the weight given in paragraph (a) of this section, to enable the airplane to meet the climb requirements of §§25.119 and 25.121(d), assuming that the fuel is jettisoned under the conditions, except weight, found least favorable during the flight tests prescribed in paragraph (c) of this section.

The takeoff analysis software will therefore include a calculation checking if the aircraft can return for an immediate landing, the only aircraft that I have seen affected by this was the MD11 which actually had a takeoff limit code of "D", indicating that it couldn't dump enough fuel to land within that 15 minutes. So I believe that my statement still stands, if it an takeoff on it, it can land on it.

dohouch

Somebody compared this debate ,runway length, to the debate over the correct height for the Dublin Port Tunnel,
except of course aviation freight is more varied and demanding.