Runway Length

[Dublin Man]

Hi All
Anyone know why the 12000ft runway seems to be the standard

[hetfield]

Hi All
Anyone know why 17.5 cm seems to be the standard

[barit1]

Don't think it's a "standard" per se - but I can think of practical considerations: neighborhood property values, etc.

And then there's the TOGW issue: with more runway available, some planes might be able to carry more payload (or fuel), but then you can run into tire speed limits (higher Vr) or other physical issues.

Given present technology, there's probably little payoff in a longer runway.

[Sir George Cayley]

Many runways are 3000m which I think were a result of Boeings design requirements for the 747.

4000m allows for a greater payload/range.

[OverRun]

Not sure how standard the 12,000 feet is. 12,000 feet = 3658m (since I think in metres these days). It's a useful length, with a 747-400 getting off in that length at MTOW and at standard ISA and 3000 feet airport elevation, or at ISA + 17 oC and 1500 feet airport elevation. As Sir GC says, the 747 dominated new airport design for many years, and many airports have been built to that sort of design. My observations over the last few years though have been around three different classes of runway length. These have been designed as (and these are not necessarily representative of existing airports):

- 2600m (8500 ft), allowing widebody aircraft flying shortish (5 hour) flights and narrow bodies most everywhere,
- 3300m (10,800 ft) allowing widebodies flying serious intercontinental distances,
- 4500m (14,750) ft) which seems to be preserve of various sheiks trying to outdo the neighbouring sheik.

barit1 touched on a couple of useful points. Firstly, with modern technology, there is little point indeed in longer runways. The widebody twins can haul a big load off a short runway, and designs for the A330 class aircraft are now for shorter runways. Secondly, and a big problem, is the advent of runway end safety areas (RESAs). These add a current required 90m at each end of the runway, or future 240m at each end. It has substantially changed the overall length needed and for new airports, I now automatically add half a kilometre to any planning length of a runway or airport for the RESAs, and that causes a lot of angst.

[jackcarls0n]

Emergency Landing point for a Space Shuttle maybe ?

Just kidding there, I thought the normal runway length was 10,000 Ft. Anyway, another reason I could think of is, due to safety and better usage of the runway. Could be that they need longer taxi way to accomodate more traffic ...so a longer runway?

[Turbine D]

IMO, airport runway length is a result of what an individual airport businesses are, e.g., if they are a major airfreight hub besides passenger service, the runways will be longer. Also, in the USA, some commercial airports once were military air force bases or even today, serve both functions and some are at high altitude and can be hot during the summer months such as Denver's airport.

I have attached an airport master planning review for the Dayton, Ohio international Airport that discusses in some detail runway lengths based on aircraft. Surprisingly the recommended runway length for a B737-900 series MTOW is 12,800 feet (3,900 meters).

http://www.landrum-brown.com/MasterP...t%202-9-05.pdf

Also, the FAA gives design recommendations and requirements for runways in the document below:

AC 150/5325-4B - Runway Length Requirements for Airport Design - Document Information

At JFK International, the most used 14,572 ft (4423 meters) runway 13R/31L was intended to be a backup runway for the Space Shuttle although it hasn't been used for this purpose. It was recently repaved in concrete and widened to 200 ft for the Airbus A-380.

[OverRun]

Thanks Turbine D for the links. I'm a little surprised at the runway length for a 737-900 at Dayton. I read the FAA document, and in the Appendix 3, they actually give an example using the 737-900. Coincidently at the same elevation and design temperature as the Dayton study. That FAA example was a runway length of 9,000 feet - not 12,800 feet - which fits better with my experiences.

[Turbine D]

Hi OverRun,

I noticed that difference as well before yesterday's post and thought I would return to the two links to see what the differences might be. I have done that and I can't account for the Dayton airport planning recommendation. The two main parallel runways for all purposes are flat, no change in elevation from one end to the other. There are periods during the summer when the ambient temperatures exceed 90℉ (32.2°C), but that shouldn't increase recommended runway length by 3,800 ft. So I am at a loss to explain the difference between the two recommendations.

Turbine D

[galaxy flyer]

Could the additional 3,800 feet be a economic stimulus package? Dayton's airline traffic can hardly require it.

GF

[Flapping_Madly]

Slightly off topic but still on runways please may I ask a stupid question?
Why has Gatwick the worlds busiest single runway airport got two runways?
Or have I finally gone doolally.

[barit1]

12,800 at DAY?

Back when Emery was operating DC-8's out of DAY that might have been a issue. Anybody got some DC-8 figures?

Could Landrum-Brown have gotten the a/c types switched?

[DZPILOT87]

Runways in the Gulf region tends to be 15000 ft long .... 30 % of the total cost is paid by the us gov (NASA) so they could land their space ships in case of incident .........etc

The second reason due to the high temperatures, humidity (affects Density altitude) average temps during summer between june and august
45-55 degreess celsius and humdity of 88 %

[Turbine D]

baret1

Here is a link to Boeing's site for the DC-8, all models. Just roughly scanning over it, it looks like you need at least a 10,000 ft runway at MTOW for a CFM56-2 engine equipped DC-8 freighter, and somewhat longer for the JT3-D engine equipped DC-8 freighter.

http://www.boeing.com/commercial/air...ps/dc8sec9.pdf

[mike-wsm]

Long runways with hard surfaces just encourage companies to design larger, faster and noisier aircraft. If we had grass strips of 400 yards we would be flying in much safer aircraft, burning much less polluting fuel and, hopefully, seeing stick and string biplanes again. No need to carry tgu*, just fly for pleasure.

*tgu: the great unwashed, aka pax or slf.

[Turbine D]

galaxy flyer

I don't know if they were doing "stimulus" projects five 6 years ago when this planning study was done for Dayton. At that time, the airport was hurting as US Air (largest airline presence) had basically abandoned their operations there. So Dayton was probably searching to fill the void with new airlines and air freight companies and hired Landrum-Brown to do this study. BTW, things have improved somewhat in Dayton, but CVG (Cincinnati) has gone on hard times with the departure of the Delta "hub" after the NWA merger.

Turbine D

[mutt]

Runways in the Gulf region tends to be 15000 ft long

I can think of one and that's Doha..... Are there any others that are 15,000 ft?

There are a lot of 12-14000 feet runways.

Mutt

[OverRun]

Doha is the longest I've come across, and rumour amongst the builders was that one-upmanship was part of the design process.

The only other very very long one I know of in the area is the first of the runways at Jebel Ali ... Dubai World Central ... Al Maktoum International Airport (JXB) which is reportedly 4500m long.

There is a new airbase in the region for which construction tenders are being submitted at present - not sure of the name or length but will see what I can find.

[Turbine D]

mutt

Yes, runway 16R/34L at DEN (Denver) is 16,000 ft.

Turbine D