Airstrip Improvements, Any Ideas?
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Airstrip Improvements, Any Ideas?
I am, at this moment, sitting in the reception area at Club Med Lindeman Island overlooking the beautiful Whitsunday Islands with a clear blue sky and an ever so slight breeze.
So today I feel lucky.
But the owner of VH-CBG doesn't. The beautiful Beechcraft Baron is sitting at the end of the landing strip with no props. Apparently the victim of a soft strip.
I understand that the local charter ops refuse to land here anymore because of the quality of the strip. What can be done to improve it? Is it just a matter of some gravel to fill some depressions or is a complete regrade in order?
How do you fix a strip?
So today I feel lucky.
But the owner of VH-CBG doesn't. The beautiful Beechcraft Baron is sitting at the end of the landing strip with no props. Apparently the victim of a soft strip.
I understand that the local charter ops refuse to land here anymore because of the quality of the strip. What can be done to improve it? Is it just a matter of some gravel to fill some depressions or is a complete regrade in order?
How do you fix a strip?
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If the strip is soft, it shows that there is inadequate drainage, or poor material used for the construction - or both. It's vital to airstrip construction that all subterranean water movement be identified and diverted via interception of the flows - either by drainage via open drain, or by perforated PVC piping commonly known as "Draincoil".
In areas where water pressure is constant over a wide area, impermeable geotextiles are called for, to prevent water ingress into the sub-base, which softens and destroys it. The area is excavated and compacted - geotextile fabric is laid, and then the base material placed on top and compacted.
Final grading and compaction, coupled with adequate crown on the strip, ensures that water ingress from rainfall is minimal. If the strip is sealed with a bitumenous product, water ingress is reduced to virtually nil, and the strip life is greatly lengthened.
The problem area has to be excavated to a depth that allows for a satisfactory depth of construction base material, inline with expected loads. A minimum of 150mm for light aircraft, 300mm for medium weight aircraft. Compaction to around 98% is then carried out. Good compaction to a high standard is critical after the subterranean water ingress problem is cured.
Heavy aircraft runway construction requirements are substantial, and involve much greater depths of excavation, greater depths of base materials, and much tighter controls on water ingress, base materials, and compaction. Extensive testing on base materials is normally carried out by soil labs, to ensure that defined parameters such as clay content, contraction and expansion rates, and fine and coarse materials content %'s are met.
The problems with Lindeman airstrip would be common with most Pacific islands. Relatively high rainfall, poor drainage, and poor construction materials.
In WW2, crushed coral was found to be an excellent construction base material.
Nowadays, you would probably find that construction base materials would have to be barged in from the mainland - as digging up the Barrier Reef for your airstrip construction materials, would possibly be frowned on ...
The good news is that seawater can be used for the compaction aid, as rainwater isn't necessary. Seawater aids in, and improves compaction rates.
I have to agree with the other blokes. Having to actually work - or even consider work - whilst on Lindeman - must be tantamount to some kind of torture. However, if I was paid enough, I'd repair your airstrip for you ....
In areas where water pressure is constant over a wide area, impermeable geotextiles are called for, to prevent water ingress into the sub-base, which softens and destroys it. The area is excavated and compacted - geotextile fabric is laid, and then the base material placed on top and compacted.
Final grading and compaction, coupled with adequate crown on the strip, ensures that water ingress from rainfall is minimal. If the strip is sealed with a bitumenous product, water ingress is reduced to virtually nil, and the strip life is greatly lengthened.
The problem area has to be excavated to a depth that allows for a satisfactory depth of construction base material, inline with expected loads. A minimum of 150mm for light aircraft, 300mm for medium weight aircraft. Compaction to around 98% is then carried out. Good compaction to a high standard is critical after the subterranean water ingress problem is cured.
Heavy aircraft runway construction requirements are substantial, and involve much greater depths of excavation, greater depths of base materials, and much tighter controls on water ingress, base materials, and compaction. Extensive testing on base materials is normally carried out by soil labs, to ensure that defined parameters such as clay content, contraction and expansion rates, and fine and coarse materials content %'s are met.
The problems with Lindeman airstrip would be common with most Pacific islands. Relatively high rainfall, poor drainage, and poor construction materials.
In WW2, crushed coral was found to be an excellent construction base material.
Nowadays, you would probably find that construction base materials would have to be barged in from the mainland - as digging up the Barrier Reef for your airstrip construction materials, would possibly be frowned on ...
The good news is that seawater can be used for the compaction aid, as rainwater isn't necessary. Seawater aids in, and improves compaction rates.
I have to agree with the other blokes. Having to actually work - or even consider work - whilst on Lindeman - must be tantamount to some kind of torture. However, if I was paid enough, I'd repair your airstrip for you ....
Agree, crushed coral and drainage. Bet the problem is more due to mega dry sand. Watering the strip every night and giving it a roll with a viberoller could bring it up to spec. Happy to come up for a few months and attempt it
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Yes well I was ppruning at 9.30am and the bar didn't open until 10.00am. Left me a bit of time to work before I had to chuck down a quick coffee before heading to the ferry back to Hamilton Is.
Thanks for your response onetrack.
I don't think the airstrip used any construction materials other than chopping down trees and grading the dirt sort of flatish (on a slight down hill with a few bumps thrown in for good measure). It would be a great destination for pilots looking for a getaway if the airstrip could be brought up to standard.
Apparently the owner of the Baron is a senior exec in CASA and was very red faced about his landing. Even had to cut his holiday short to get the props fixed.
Thanks for your response onetrack.
I don't think the airstrip used any construction materials other than chopping down trees and grading the dirt sort of flatish (on a slight down hill with a few bumps thrown in for good measure). It would be a great destination for pilots looking for a getaway if the airstrip could be brought up to standard.
Apparently the owner of the Baron is a senior exec in CASA and was very red faced about his landing. Even had to cut his holiday short to get the props fixed.
Don't know why the strip would be soft! It is the dry season after all!
The strip can be slippery in the wet, but I have never seen anyone bogged.
Unless they weren't on the strip!
The strip can be slippery in the wet, but I have never seen anyone bogged.
Unless they weren't on the strip!
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It is over 15 years ago now...
But we never had any major problems with the Islanders, Partenavias and Cesnnas. It would get a bit soggy but north/south strip was usually OK - there was a base of gravel laid and rolled onto the eastern side of that strip some 15 odd years ago. That particular area was moderately weather resistant. The roller etc was brought by a barge from Shute.
I know back in those days private and commercial ops who were not intimately familiar with the strip were not permitted to operate there. I am not familiar with current procedures and if that has been relaxed.......
Sorry to hear about the Baron and driver. I am sure it is not a nice feeling for anyone.
But we never had any major problems with the Islanders, Partenavias and Cesnnas. It would get a bit soggy but north/south strip was usually OK - there was a base of gravel laid and rolled onto the eastern side of that strip some 15 odd years ago. That particular area was moderately weather resistant. The roller etc was brought by a barge from Shute.
I know back in those days private and commercial ops who were not intimately familiar with the strip were not permitted to operate there. I am not familiar with current procedures and if that has been relaxed.......
Sorry to hear about the Baron and driver. I am sure it is not a nice feeling for anyone.
