Essendon RWY Strip Width discrepancy
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Essendon RWY Strip Width discrepancy
Interesting email today from the AFAP regarding Essendon RWY26/08.
It mentions that the strip must be at least 300M wide for Precision/ Non Precision Approaches. Due to the DFO and other structures, it’s only 230M.
My question is who’s responsible? Which of the many strict liability offences are we committing by accepting an ILS onto 26?
It mentions that the strip must be at least 300M wide for Precision/ Non Precision Approaches. Due to the DFO and other structures, it’s only 230M.
My question is who’s responsible? Which of the many strict liability offences are we committing by accepting an ILS onto 26?
Bloggs - reasonable point. I'll go with - "Well, the Regulator knows about it, and hasn't done anything about it, therefore they must deem it safe!"
Last edited by josephfeatherweight; 1st Feb 2018 at 11:29.
The whole thing is probably an elaborate (and deliberate) plot to close down Essendon once and for all
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Don't worry, CASA will just construct a 'safety case' and issue a waiver as everyone know's that the horse has well and truly bolted on this one.
Money talks - and the greed, back slapping and dodgy deals that allowed an aerodrome to be converted into a commercial retail district would make a great article.
Money talks - and the greed, back slapping and dodgy deals that allowed an aerodrome to be converted into a commercial retail district would make a great article.
Sufficient evidence that it’s safe to continue operations as there have been no accidents despite being too narrow, standby for a rule change. Very clever use of flight testing using revenue flights?
Don't worry, CASA will just construct a 'safety case' and issue a waiver as everyone know's that the horse has well and truly bolted on this one.
Money talks - and the greed, back slapping and dodgy deals that allowed an aerodrome to be converted into a commercial retail district would make a great article.
Money talks - and the greed, back slapping and dodgy deals that allowed an aerodrome to be converted into a commercial retail district would make a great article.
It would have been better if the AFAP had also published CASA's response to the issue. In other words, the whole thing appears to be a non-issue, although CASA could make the text in ERSA a little clearer: "bl@@dy big buildings just inside the RWS on southern side" as opposed to myriad obstacle notes (one of which has got a bearing digit missing).
Are you assuming that the position of the gable markers indicate the runway strip? I think you'll find this is incorrect.
According the current MOS 139 gable markers are placed to indicate the limit of the graded portion of the runway strip (MOS 8.2.2). If you read the section on runway strip widths you will find that it is possible to declare a runway strip beyond where the gable markers are placed. Is that not the situation here?
It also goes on to describe the fly over area and how close to the centreline objects within the strip can be placed. It actually says that objects can be within the strip if certain parameters are met. Some interesting things regarding transverse slope.
Without knowing how the areas beyond the graded strip are set up it seems like the strip is compliant and the AFAP could be mistaken. Unless I have misread MOS 139.
Alpha
According the current MOS 139 gable markers are placed to indicate the limit of the graded portion of the runway strip (MOS 8.2.2). If you read the section on runway strip widths you will find that it is possible to declare a runway strip beyond where the gable markers are placed. Is that not the situation here?
It also goes on to describe the fly over area and how close to the centreline objects within the strip can be placed. It actually says that objects can be within the strip if certain parameters are met. Some interesting things regarding transverse slope.
Without knowing how the areas beyond the graded strip are set up it seems like the strip is compliant and the AFAP could be mistaken. Unless I have misread MOS 139.
Alpha
So it’s possible for aircraft (and other things) to be outside the gable markers at an aerodrome but still on the runway?
According to the wording in MOS 139. Yes.
Im not sure they are considered to be still on the runway. Only considered to be within the strip. The wording explains that when the runway is in use the graded area must be free of obstruction, and that's where the gable markers are.
Im not sure they are considered to be still on the runway. Only considered to be within the strip. The wording explains that when the runway is in use the graded area must be free of obstruction, and that's where the gable markers are.
Hmmm. The point of having part of the runway strip outside the gable markers is not obvious to me, if aircraft and other obstacles can be there while the runway is in use.
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Lead Balloon
Mos 139 6.4 relates to holding points and in particular distance from centreline. This is where the 90m and 150 m graded strips largely come in. Precision approach runway holding points are even further back from centreline at a descending scale along the runway depending on elevation of the holding point in relation to the threshold.
Aircraft at a holding point, usually in line with the gables, are considered to be clear of the runway. But the holding point is often not coincident with the gables.
The 300m runway strip does not relate to ground markings or gables and I have never seen one marked, although it may happen. It is a distance off centreline for the surveyor to reference, not aircraft.
Mos 139 6.4 relates to holding points and in particular distance from centreline. This is where the 90m and 150 m graded strips largely come in. Precision approach runway holding points are even further back from centreline at a descending scale along the runway depending on elevation of the holding point in relation to the threshold.
Aircraft at a holding point, usually in line with the gables, are considered to be clear of the runway. But the holding point is often not coincident with the gables.
The 300m runway strip does not relate to ground markings or gables and I have never seen one marked, although it may happen. It is a distance off centreline for the surveyor to reference, not aircraft.
The section outside the graded portion, but within the designated RWS width is known as the flyover. It must be kept clear of fixed objects that project through a plane that starts at the edge of the graded area (the gable line) and extends upwards at 5%. It's purpose is not for the wayward ground movement of aircraft (that's what the graded part is for), but for protection of very low altitude manoeuvring adjacent to the RWY. For a Precision I, II, or III Runway with code number 3 or 4E only the area within 60m of the RWY centre line needs to be kept clear of mobile objects. The gable line is usually used as the reference, but this is actually outside this line. You can have transitory obstacles - vehicles etc - within the RWS as long as they are outside the 60m. As I said, mostly the gable line is used as this is easier.
There is an escape clause for the AD operator who cannot meet the RWS requirements. MOS139 Section 6.2.18.4 refers.
There is an escape clause for the AD operator who cannot meet the RWS requirements. MOS139 Section 6.2.18.4 refers.
Thanks TIEW. That makes sense. I’ve learned something. 