min rwy width B737

[OverRun]

Was at last able to haul out the paperwork and find, from the Australian AIP ENR 60_1, the definition sought by 737incognito, which is:

An aeroplane's reference field length is:
(1) in the case of an aeroplane to which section 20.7.1B of the Civil Aviation Orders applies (see below but basically civil turbines & jets) – the balanced field length; or
(2) in the case of any other aeroplane – the take-off distance; that the aeroplane requires for take-off in accordance with subpara b. below:
b. For the purposes of sub-para a. (1) and (2) above, the balanced field length or take-off distance that an aeroplane requires for take-off is the balanced field length or take-off distance that, according to its flight manual, the aeroplane requires:
(i) on a level runway,
(ii) at maximum take-off weight,
(iii) in still air,
(iv)at sea level, and
(v) in standard atmospheric conditions.


Section 20.7.1B of the Civil Aviation Orders says:
Subject to paragraph 2.2, this section applies to:
(a) all turbine powered aeroplanes having a maximum take-off weight in
excess of 5 700 kg; and
(b) all new types of piston engine aeroplanes having a maximum take-off
weight in excess of 5 700 kg placed on the Register after 1 June 1963.
2.2 For paragraph 2.1:
(a) a certificate of airworthiness for the aircraft must be in force; and
(b) the certificate must include a statement to the effect that the certificate is issued in the transport, commuter or normal category.

[Aeroengineer1]

Reference Field Length

According to ICAO Doc 9157 Aerodrome Design Manual, Part-1, Runways (2nd ed):

The aeroplane reference field length is defined as the minimum field length required for take-off at maximum certificated take-off mass, sea level, standard atmospheric conditions, still air and zero runway slope, as shown in the appropriate aeroplane flight manual prescribed by the certificating authority or equivalent data from the aeroplane manufacturer.

Similar definition exists in ICAO Annex 14, Chapter I - General:


Aeroplane reference field length.

The minimum field length required for take-off at maximum certificated take-off mass, sea level, standard atmospheric conditions, still air and zero runway slope, as shown in the appropriate aeroplane flight manual prescribed by the certificating authority or equivalent data from the aeroplane manufacturer. Field length means balanced field length for aeroplanes, if applicable, or take-off distance in other cases.

Regarding Boeing 737 narrow runway operations some descriptive information can be found in Boeing presentation entitled "Guidelines for Narrow Runway Operations" by Rob Root, Flight Operations Engineer, Flight Technical Services, Boeing Commercial Airplanes. I guess you can all find the document elsewhere on the net.

[Aeroengineer1]

I am familiar with B737 ops on 30m wide runways - both the -400 and the -800 series. They are normal at several Australian aerodromes, such as Ayres Rock and the busy Gold Coast/Coolangatta;

I just wonder whether these 30m runways have 7.5 meters wide paved shoulders on both sides?

[Aeroengineer1]

Boeing program?

Boeing has a special takeoff analysis program for operating the B737 from narrow runways, although, under the FAA system they do not have any limitation on the runway width.

Anyone who has this program of Boeing?

[OverRun]

Ayres Rock is 30m wide without 7.5m sealed shoulders. I just talked to them now to confirm.
Gold Coast/Coolangatta is now 45m wide, 7.5m sealed shoulders (been that way for quite a while) and has just been lengthened to 2492m. But up the road from them is the new Hervey Bay airport – 30m runway width with ops by Virgin Blue 737-700s and -800s, and also without 7,5m sealed shoulders.
The issue of the 7.5m sealed shoulders, and their protection against FOD has been on my plate at a few airports lately. ICAO require the shoulders to have bearing strength plus measures to avoid ingestion of loose stones. This can only be reliably provided for jet aircraft by using bitumen or concrete surfaced shoulders at most airports. Some airports, with good strong soil + moderate rainfall + few jet operations to erode the soil + good maintenance, can use grass/soil shoulders, but this is the exception rather than the rule. Some national authorities make it simple, and state that bitumen/surfaced shoulders SHALL be provided where 7.5m shoulders are required.
For the airport assessing risk, well if an aircraft goes off the side of the runway and there is a problem or it ingests stone/damages an engine, one of the first things to be looked at will be the shoulders and if the airport's position will be difficult if they are not surfaced.
The Boeing presentation is great - pulls together all the factors - thanks be to 'wing files'
Boeing narrow runways

[737incognito]

Thanks everybody, especially Aeroengineer1.
I've found Boeing presentation on http://www.wingfiles.com/ and it was great help.

[Aeroengineer1]

Supplement to AFM and OM regarding narrow runway ops

Your welcome 737Incognito.

Now, I have a question after reading Boeing's narrow runway document.

Does Boeing provide supplement pages to AFM regarding narrow runway operations?

And, I assume that the operator should add some procedures pages in the OM. Am I right?

If I were the civil aviation authority, I would ask the operator to fulfill these. What is your opinion, people?

[Aeroengineer1]

-300 and -800

From OverRun's comments in another thread:

This started me thinking about the original question by Prof2MDA on runway width. Taking the design? normal? engine failure case on takeoff where Vef is just above true Vmcg. The aircraft will probably have wandered slightly off centreline during takeoff anyway; I don't have the relevant research to hand, but from memory a normal aircraft wander could be up to say 5m off centreline. Then given a wheeltrack (distance between the outer tyres of the outer main gears of approximately 12.6m for a 747-400, this places the outer tyres at (12.6/2 + 5=) 11.3m off centreline. Then have an engine failure just above Vmcg and experience a parallel path departure of 9m allowed in the regs, and the outer wheels are now (11.3 + 9 =) 20.3m off centreline. If the minimum clearance between the outer tyre and the edge of the runway was set to be 1.5m (my estimate to allow for load spreading in the lower pavement), then that is equivalent to a minimum runway width of (20.3+1.5)*2 = 43.6m. Hmm - doesn’t leave much fat in a 45m wide runway.

I did some work regarding 737-300 and 800 for 2m initial offset from centreline. Regulations allow 9.14 m deviation after engine failure above Vmcg. In case of 737-300, after an engine failure, the distance between outer edges of outer tyres and runway edge becomes 0.655 m, and engine CL goes 0.966 m out of runway. These figures become 0.36 m and 0.966 m respectively for 737-800 case. I am now confused about 737 operations on narrow runways and especially on such runways without paved shoulders. What if initial offset is 3 m? Note: I am not a pilot... Any pilot opinion?

[OverRun]

The required minimum runway width obviously varies depending on how close to the centreline the aircraft is when the engine fails. Assuming that aircraft wander patterns are normally distributed, based on field measurements (Brown, D.N. and Thompson, O.O. (1973). "Lateral Distribution of Aircraft Traffic,"Miscellaneous Paper S-73-56, U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg, MS.), the distribution of aircraft on runways is assumed to have a standard deviation of 1.55 m. So at the 95% confidence level, this is mean + 2 s.d = 3.1m. Aeroengineer1 had used 2m (which is the 80% confidence level - also a reasonable assumption). Either 2 or 3m could be used, and I now think that the 5m value used in my earlier post was too conservative.

Aeroengineer1 calculated the Boeing 737-800 outer wheels to be 0.36m inside the runway for the 30m wide runway and a 9m lateral deviation. That is at the 80% confidence level. At the 95% confidence level, the outer tyre would be 0.74 m outside the runway (and onto the runway shoulder).

The Boeing way of handling this seems to be to reduce the takeoff thrust, and load to more forward CG to improve directional control. This would reduce the lateral deviation to less than 9m, and so even at the 95% confidence level, should keep the aircraft on the 30m wide runway, albeit very close to the edge.

When the wheel is on the runway edge, the load and load spreading will be taken partly by the runway and partly by the material/subgrade in the shoulders. Since the number of aircraft ever doing this is hopefully very few, we need only design for a few passes. It should be OK, provided the shoulder pavement material is kept dry. From the highway concepts of edge wetting and shoulders, we know that a sealed shoulder of 1,5m protects the edge of the carriageway from the edge wetting effects of rainfall. So to be sure about 737 operations on a 30m wide runway, we might look at something like a 1.5m sealed shoulder with a bearing strength suited to a couple of passes of the aircraft.

The engine is hanging out a bit further than the wheels, and is well out over the shoulder. But then it is probably the engine that failed, causing the yaw in the first place. So there may not be too much risk of FOD.

This accords with slide 18 of Root's Boeing presentation:
No regulatory link between VMCG definition and actual runway width, so the maximum 30ft deviation could result in reduced (or nonexistent) clearance between outboard main landing gear tire[s] and runway edge…
and his slide 30:
Increased risk of Foreign Object Damage (FOD) to wing-mounted engines

The real trick now is get the 747 onto the 30m runway - here's how it is done

[Aeroengineer1]

Still difficult to conclude

Thank you OverRun.

After all of this discussion, I think we can conclude that min runway width for 737 can be 30 meters only with some limitations. If we do not want any limitations then min runway width for 737 becomes 45 meters.

However, I still could not get any response regarding AFM and OM supplements for "narrow runway" operations. I wonder if there are any pilots in this community, who have seen such supplemental pages in AFM and OM about "narrow runway" operations of 737.

[john_tullamarine]

.. when narrow runway ops acquired an airworthiness interest in Australia, along with some test requirements, the normal deal involved a suitable FMS.

[mutt]

the normal deal involved a suitable FMS.

Interesting, but why?

Aeroengineer1,
Boeing considers narrow runway data as an AFM appendix, it therefore costs money. If you are a Boeing operator you can ask your tech rep for a non-operational version of the STAS program for test purposes.

AFAIK, the Australian CAA are the only ones who require performance data to be based on the runway width.

Mutt

[john_tullamarine]

Mutt,

To specify narrow runway restrictions etc ... (got to stick the words somewhere ..) ... main restriction will generally be a crosswind limitation (or an artificial increase in minV1 to get away from the Vmcg problem area) .. which relates to the best we found on the day(s) in question.