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Letter: Taking off and landing at Argyle SVG
Published on December 10, 2013 Email To Friend    Print Version

Dear Sir:

It is generally best to land uphill and takeoff downhill, but always into a headwind.

The runway is oriented at 20 degrees for an approach from the south and 200 degrees for an approach from the north. These appear to set up a consistent cross wind landing. I believe this may have an impact on safety?

At Argyle, the prevailing winds come from the north-east-east, the runway is aligned with a heading north-north-east approach, whilst the wind is north-east-east, at frequent times veering to direct east. So the runway does not head directly into the wind, the wind is most of the times blowing from the left and striking the forward right hand of the landing aircraft. Sometime blowing and surging as a side wind, which is far less than ideal, perhaps at times downright dangerous.

At Argyle, the takeoff and landing will be slightly downhill, a gradient, which is preferably the only option seeing as the runway appears misaligned to the predominant wind direction.

In an ideal world, pilots would always be able to land up-gradient with a headwind and takeoff down-gradient with a headwind. Of course that’s not possible with a single one direction runway airport, such as Argyle.

But what about the times when gradient and wind are in "opposition"? Which is best, landing uphill with a tailwind, or downhill with a headwind? Or is it better to takeoff downhill with a tailwind, or uphill with a headwind?

Knowing the effects of a runway gradient on takeoff and landing performance will give the pilot an extra safety margin, especially when deciding whether a takeoff would be prudent with a given aircraft weight, wind, and density altitude.

With a sea approach to the ingress of the runway means passing over a high cliff or bluff at Argyle. Depending on the speed of the north-east-east wind, I have recorded a serious downdraft on three occasions, special attention by pilots will be required as a downward pull may well occur when the aircraft is vulnerable at landing speed with fully extended flaps and landing gear. Landing from the sea approach extenuates the downdraft. Once clear of the sea and beyond the cliff, the aircraft may well experience a lift. This may create a confusing double whammy seesaw effect for pilots. Then when one third of the way along the runway, serious side winds may happen from an almost easterly wind.

A strong headwind is required to overcome the increase in landing roll that a downhill landing creates; if the wind is strong enough to cancel the effects of a downhill slope, expect a lot of turbulence on the final approach to the runway. If the approach is flown at a faster airspeed to compensate for gusts and turbulence, the increase in groundspeed will lengthen the landing roll. Also, when landing downhill the plane may well float, and float. Pilots may find it hard to touch down because the ground keeps dropping out from under the airplane. Once on the ground, the pilot is counting on brakes to stop [going downhill]. Heavier airplanes have more inertia and can be hard to stop. Reverse engine thrust may be necessary, but most pilots do not like this procedure because of the shake experience which can cause structural and mechanical damage to an aircraft if this method is used frequently.

The takeoff will again require special attention as the takeoff is over water at the egress of the runway. A strong updraft may well be there depending on the wind speed.

Pilots should use extra caution when mixing wind and runway gradient. The Argyle runway with its downhill gradient has in places surrounding side terrain such cliffs, bluffs and sharp sided hills. These can exacerbate the effects of downdrafts, wind shear, and cause turbulence on approach and departure.

Landing and taking off at Argyle, with more than a light easterly wind may not be a good idea.

There is no general international headwind limit. There may be a headwind limit for autoland (25 knots in the 747), but no general limit on manual landing. In practical terms, turbulence and other weather [rain, downdrafts, etc] will make it inadvisable to land when the surface wind is high, and may restrict ground operations before flight ops are restricted. Large aircraft have landed elsewhere in 50+ knot wind, but it is not advisable or a common practice for most commercial operators.

The FAA is looking hard at having a hard rule regarding tailwind and headwind operations. Although reasonably heavy headwind is most of the time not a bad thing. It allows the plane to take off and land at lower speeds. But what is reasonably heavy?

Of course the other problem is that there are rules that the doors to the aircraft may not be opened in adverse weather or high winds. So landing in those conditions would be rather pointless if you can't open the doors.

Common top landing crosswind limit for most commercial aircraft is around 36 knots or around 41 mph. Give or take a few knots depending on aircraft type and size. Any more crosswind speed than this could put aircraft and passengers at risk. The cross wind speed is usually stipulated by the manufacturer or/and is airline safety policy.

Gusts are more problematic than continued wind, because they are often unexpected and come as a surprise to the pilot.

Low level wind shear or severe turbulence associated with the wind are factors that could, in conjunction with high winds cause a problem.

A lot of wind observation and analysis takes place before a runway is ever constructed, so direct crosswinds are fairly uncommon on existing runways. Because those building runways know that areas with exceptionally high winds should not and are therefore not built in. Most large airports that have wind problems build multiple runways, so crosswind takeoffs and landings can be avoided as much as possible.

Most airports have multiple runways, or at the least an extra cross runway, so pilots will be able to change runways to avoid tailwind and use the headwind to shorten the takeoff run. Neither of these options has been accounted for at Argyle. In fact, the runway is being built without appropriate wind studies in place. The result could well be that the airport is unusable for up to four months of the year. It will also make the airport an unreliable destination for airlines and carriers; they will never know what to expect until they arrive to land.

Building the runway without wind studies was what anyone in the business or profession might describe as foolish at the very least, and criminal if something untoward happens in the future. When a runway is completed without wind-studies, and when the required studies are presented after completion, it could result in a runway that neither the FAA, the ICAO or any other control association will issue an approval for, commercial airlines will not be able to land there, and no insurance company will insure them to do so.

Small aircraft as operated by indigenous airline companies will be in the most serious trouble with the wind direction, etc. A cross runway should be completed at the same time as the main runway. Such a runway will be small and only suitable for the light aircraft. There is already a piece of land provided for such a facility, facing east-west. The developers are aware of the problem now, so they should fix the problem now, not wait until the small operators are forced to give up landing at Argyle. Whatever happens at Argyle, nothing they do will make Argyle suitable for small aircraft. I suppose the old airport at Arnos Vale could be kept open just for the small aircraft

I also notice that the arrival building and apron is far lower than it should be for proper operation. It may prove to be inoperable for the larger aircraft. They can raise the apron but it will leave the building in a hole, much lower than the apron.

I am reliably told the arrival building is so low that rain water and sewage will have to be pumped to elsewhere on the site. The engineering will be difficult and the cost will be enormous.

Even if embroidered wind studies were presented for Argyle, private wind studies have been going on secretly now for some time and may well be used to refute any wind study evidence that appears to be untrue. I just hope that no one is silly enough to introduce the Maurice Bishop syndrome. Bishop was known for instigating the creation of false documents to commit fraud [documentary evidence available in public records] against public international bodies.

In writing this article I do not mean to express or imply any wrongdoing or conspiracy by any living person, employee, ministry department or politician. I currently have no evidence whatsoever of wrongdoing at the Argyle airport, regarding wind studies or any other matter.

Having said all that, there are still about 59 people who have not been paid for their farmland at Argyle taken for the airport; they have remained unpaid now for several years. It’s nothing less than a national disgrace.

Most large aircraft will approach Argyle over Bequia at a fairly low altitude; Bequians should expect at times some serious, sometimes unbearable, noise pollution. Those that purchased land from the government to build holiday or permanent homes should ask their lawyers if they can get redress for the alleged withholding of such information from the buyers. The government should have been fully aware of noise pollution from their feasibility study that took place before they built the airport. Oops, did they have one of those?

The village of Stubbs will be so blighted by noise pollution it may even prove to be uninhabitable, the whole village will most probably need to be abandoned and property owners compensated. The problem is how will anyone get money from this current government, and if they are not re-elected, what a mess for the NDP.

Vincentians really need this airport, but what a mess the whole thing has turned out to be. I am really sorry to say I believe we are in trouble with the whole project.

I feel sure the airport will not open before the next election because, once it’s opened with all its problems, problems that were avoidable, no one will vote ULP, all confidence will be long gone. Whereas if they can say “give us another term to finish the airport“, they may still just scrape in, because there is plenty of ignorance attached to the airport, many ignorant people who just have to believe.

See Trip Advisor

Peter Binose
 
Reads: 3613





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Comments:

Peter Binose:
Check this out, this was in England's Birmingham airport a few days ago, gust side winds between 30 and 50mph.

These kind of side wind speed gust's occur at Argyle on and off throughout most of the year. Perhaps making Argyle a place to be avoided by international airlines. And somewhere for small aircraft to avoid like the plague.

http://tinyurl.com/khmlbdc

Peter Binose:

In the last 4 weeks 4 of LIAT’s new aircraft have been unable to take off at night because of the wind, at ET Joshua airport at Arnos Vale.

So far they have only admitted to one, so that is telling lies by omission.

Argyle private wind analysis shows far worse problems there, at least 10 times worse than Arnos Vale.

I think we are going to be deep in the do-do.


Peter Binose:
At last I have got the wind limits on our new ATR aircraft.

The ATR42 Aircraft Flight Manual indicates that the tail wind limit of the ATR42 is 15 knots and also states:

"The capability of the airplane has been satisfactorily demonstrated for take off and manual landing with tailwinds up to 15 knots. This finding does not constitute operational approval to conduct take off and landing with tail wind components in excess of 10 knots."

But they are not recommending take off and landing with tail wind components in excess of 10 knots.

The American Eagle ATR 42/72 AOM states, under "Operation Limits", the limiting tailwind component to be 10 knots.

http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20001211X11530&ntsbno=CHI99LA055&akey=1

ATR operating manual states that in wet conditions it should not do so in cross winds above 25 knots.

A restriction imposed on doors, you may not operate cargo door with a cross wind component of more than 45 kt

Ten Knots and above are the norm for Argyle, and bursts of cross winds well inexcess of 25 kt also, know wonder Brunton did a runner, those wind speeds are fairly common at Arnos Vale at certain times of the year.

PEOPLE WE ARE IN THE DO DO.


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