mozart
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Why Is SXM Runway 09 So Tricky?

Mon Feb 28, 2005 11:15 am

I always hear about about the difficult approach into SXM. My understanding is that it is sort of tricky because

- the runway is rather short for heavies (7708ft)
- go-arounds are kinda tricky because of terrain on the other end
- it can only be used in an easterly direction, even when winds are west
- visual approach with only an offset VOR as navaid, but otherwise not even PAPI lights

What other factors come in? And given that the terrain is difficult enough already why don't they build an ILS or at least other leading lights so that the chance of getting it right the first time is increased?

Thanks for any information, especially from pilots who have been to the field.

Chris
 
LimaFoxTango
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RE: Why Is SXM Runway 09 So Tricky?

Mon Feb 28, 2005 11:32 am

The approach into SXM is the easy part. It's the departure that'll get ya!! The runway is long enough for basically any aircraft. The only problem is the climbout. If those hills weren't there, you'd realise the the runway is quite adequate.

The VOR is probably not more than 100' to the left of the 09 runway threshold. There are VOR approaches that can be used. I don't know why I keep hearing this, but there are PAPI's installed on rwy 09. They're probably on rwy 27 too, but I can't confirm that.

I'm sure an ILS would be implemented once the upgrades to the runway and such are complete. At least, thats what I think. As I said, the approach into SXM is just like any other airport. The only time an ILS would come in handy is in low visability times. Those are few and far between.

Twin Otters, Islanders and other light aircraft regularly land on rwy 27 if necessary. Anything bigger than a Twin Otter probably wouldnt.
You are said to be a good pilot when your take-off's equal your landings.
 
AirWillie6475
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RE: Why Is SXM Runway 09 So Tricky?

Mon Feb 28, 2005 1:01 pm

I really doubt that the terrain causes much trouble on takeoff. The reason why it is an approach that requires attention is because its a visual approach and the runway is very close to the water. You have to imagine how the runway looks like to the pilots, they wouldn't even see the beach. The runway would be meeting the water.

I was taught to be very careful when landing on runways that are surrounded by feturelessness such as water or snow because because your eyes will think that you are high and you will subconsciouly have a lower approach. Its an opticlal illusion. Plus realisticaly the pilots don't see the papi lights untill 3 to 5 miles witch is not that much. As far as the ILS goes, its pretty expensive to setup. If the airport owners think they could justify the costs then they would have had one long time ago.
 
sovietjet
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RE: Why Is SXM Runway 09 So Tricky?

Mon Feb 28, 2005 2:56 pm

Why can't they take off towards the beach?
 
OPNLguy
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RE: Why Is SXM Runway 09 So Tricky?

Mon Feb 28, 2005 3:39 pm

>>>I really doubt that the terrain causes much trouble on takeoff.

With all due respect, terrain -can- be very problematic for takeoffs. Terrain constitutes being an "obstacle" and depending upon its location(s) relative to the runway centerline and distance from the end of the runway, takeoff weights can be adversely affected for some aircraft.

My of my coworkers at a former airline once tankered 40,000 lbs of fuel into SXM (DC-10) on the assumption that the next flight would later depart on 27. Lo and behold, the winds shifted out of the east and 27 was now out of tailwind limits. With the terrain east of the airport, the max takeoff weight for 09 was far less than that of 27 (even with a 15 knot headwind credit for 09) and the flight was overweight. With no defueling capability there (at the time) the only solution was to run the flight SXM-SJU with half the pax, and make a second trip SXM-SJU for the other half, eventually continuing SJU non-stop (with everyone) to wherever the originally intended destination from SXM was.

"Black hole" approaches can also be problematic, but that's a separate issue.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
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Starlionblue
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RE: Why Is SXM Runway 09 So Tricky?

Mon Feb 28, 2005 8:51 pm

An ILS system is, as has been said, not free. I doubt there are many days at SXM which would require an instrumental approach.
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LimaFoxTango
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RE: Why Is SXM Runway 09 So Tricky?

Mon Feb 28, 2005 9:12 pm

Quoting AirWillie6475 (reply 2):
I really doubt that the terrain causes much trouble on takeoff.


Actually it does. The winds coming down the hills can really be terrible at times. That is why an immediate turn is required after take off. I've seen aircraft (Twin Otters, Islander's etc) begin their turn a 150' just to avoid turbulence. The closer to the hills you are, the more turbulent it will be.


Quoting Sovietjet (reply 3):
Why can't they take off towards the beach?


The average wind speed out of the east is probably between 10-15kts which is probably outside the tailwind limit for many aircraft.


Quoting Starlionblue (reply 5):
I doubt there are many days at SXM which would require an instrumental approach.


Exactly. Although an ILS would be handy at any airport, SXM wouldnt really need it 365 days a year. Only some days are really bad in terms of low visability, but those are somewhat rare.
You are said to be a good pilot when your take-off's equal your landings.
 
DColeMAN
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RE: Why Is SXM Runway 09 So Tricky?

Tue Mar 01, 2005 2:38 am

Quoting LimaFoxTango (reply 6):
Quoting Sovietjet (reply 3):
Why can't they take off towards the beach?

The average wind speed out of the east is probably between 10-15kts which is probably outside the tailwind limit for many aircraft.


There are occasionally departures from Rwy 27 though.

Dale
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LimaFoxTango
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RE: Why Is SXM Runway 09 So Tricky?

Tue Mar 01, 2005 4:57 am

Quoting DColeMAN (reply 7):
There are occasionally departures from Rwy 27 though.


Of course. That only happens when the winds die down though. Those days are quite rare.
You are said to be a good pilot when your take-off's equal your landings.
 
bio15
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RE: Why Is SXM Runway 09 So Tricky?

Thu Mar 03, 2005 12:04 pm

Hi LFT, you wrote the following:

Quoting LimaFoxTango (reply 6):
The average wind speed out of the east is probably between 10-15kts which is probably outside the tailwind limit for many aircraft.


This got me thinking, what do you mean by "tailwind limit for many aircraft"? What I understand from your reply is that the tailwind is high enough for the aircraft to have a hard time to reach V1, or not reach it at all. Is that interpretation correct? I also thought about tire speed limit, but I believe this is far from V1+15, right?

Thanks in advance

Alfredo
 
LimaFoxTango
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RE: Why Is SXM Runway 09 So Tricky?

Fri Mar 04, 2005 7:51 am

Quoting Bio15 (reply 9):
This got me thinking, what do you mean by "tailwind limit for many aircraft"?


There is a certain tailwind speed limit to which an aircraft can land and/or take off in. For landing example, lets say an aircraft has a tailwind landing limit of 10kts and there is a windspeed of 12kts at 110 degrees. If said aircraft wanted to land runway 27, it cannot legally do so because the wind speed (which would be a tailwind in this case) is greater than the aircraft's limit. In laymans terms, the ground speed of the aircraft would be too great to make a "normal" landing.

I may not have explained it well enough, so I'll let someone else do it. I hope you understand anyway.

PS. In case you or anyone else is wondering, I don't think there is such a thing as a "headwind" limit  Smile.
You are said to be a good pilot when your take-off's equal your landings.
 
bio15
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RE: Why Is SXM Runway 09 So Tricky?

Fri Mar 04, 2005 9:20 am

Hi LFT, from what I understand, the tailwind limit is basically another way of calling the tire speed limit. I'm familiar with the fact that the tires are speed limited, meaning that they have a ground speed limit and if they roll any faster than that then they are not guaranteed to work properly. I understand your point, thanks.


*****
As I mentioned in my post, I thought about tire speed limit. I thought this speed should probably be VR+15 (accounting for a 15 knot tailwind on takeoff) or Vref+XX+15 (accounting for flaps damaged + 15 knot tailwind). I assume the aircraft is designed with a tire speed limit above both these figures.

Another way to see the tailwind limit might be a tailwind that 'limits' the runway length significantly. With a strong enough tailwind the aircraft might not reach V1 when past the "start braking" point. Are there charts for this kind of situation?

*****

These are some thoughts of mine, can someone tell me if I'm on the right track with this issue?

Alfredo
 
SlamClick
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RE: Why Is SXM Runway 09 So Tricky?

Fri Mar 04, 2005 9:58 am

Quoting Bio15 (reply 11):
Hi LFT, from what I understand, the tailwind limit is basically another way of calling the tire speed limit


Quoting Bio15 (reply 11):
These are some thoughts of mine, can someone tell me if I'm on the right track with this issue?


Well, yes and no.

There is an ABSOLUTE tailwind limit for any given airliner for takeoff or landing. It has nothing to do with runway length, gross weight, flap setting, runway slope, V-speeds or obstacles in the departure corridor. It is a seemingly-arbitrary number that is just part of the type certificate for that airplane. Airlines are permitted to set a company limit as well, which may be more restrictive but may not be less restrictive.

The last plane I flew this limit was ten knots.

Now VR might have been somewhere around 145-160 knots for most takeoffs, and the tire speed limit was 225 mph or about 195 knots TRUE airspeed. So a ten knot tailwind would not put us anywhere near the tire speed limits. Those numbers are pretty much in the range of most narrow body jetliners in the 120-200 passenger range.

Accelerate-stop distance is increased by tailwinds.
Climb angle required to clear obstacles in the departure corridor is increased by tailwinds because you get to them sooner.
Climb gradients are flattened by tailwinds because the gradients are given in % which is "rise over run."
But these things aside, there is still the absolute limit for the plane.

In fact, I've only made one tire-speed limited takeoff in my whole career. It was a hot day at a high elevation airport with no obstructions and we were in a DC-9-15 with no leading edge slats. VR was 187 knots!
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bio15
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RE: Why Is SXM Runway 09 So Tricky?

Fri Mar 04, 2005 12:36 pm

Hi Slamclick, thanks for your response, that clears it all up for me. Now I understand that airliners have a tail wind limit, regardless of all the factors I mentioned.

I did have a vague idea in my head that the speed tire limit would be up in the 220's speed range, way higher than VR, or most other V speeds, which sounds logical from a designers point of view.

Nice anecdote BTW, a 187 knot takeoff is pretty fast! Big grin Thanks again

Alfredo

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