Posts: 173
Joined: Mon Jun 10, 2002 8:29 pm

747's At St Maarten.

Sun Sep 15, 2002 3:17 pm

Hi Guys,

I was just reading an article in Airways on Princess Juliana Airport in St Maarten and was wandering how the large aircraft get off the ground. 747- 200/300s of Air France, Corsair and KLM frequently visit the airport and make direct flights accross the Atlantic to Europe. It puzzles me how they are able to accomplish this.

Princess Juliana Airport (SXM) has a single runway, 9/27, which is only 7,535 x 148ft (2,297 x 45m) long. Being located in such a hot area of the world, you would expect the airport to have a very long runway in order to accommodate these large aircraft.

I live in Dubai and DXB has two 4000m (13,000ft) runways. It is not uncommon to see a fully laden Boeing 747 take up much of the runway to get off the ground. It is so hot in Dubai and the density of the air is so low that aircraft require a much longer runway to take off. You would expect the same to be the case at Princess Juliana Airport. In the UK, where it is much cooler and the air has a higher density, I doubt very much you would see a 747-300 making an Atlantinc crossing from an airfield such as Leeds Bradford or Liverpool. I use those two examples as they have runway lengths similar to that of Princess Juliana Airport.

If a 747 had to abort take off at Princess Juliana, there is no chance it would have enough room to stop before the end of the runway.

I think it's great that the airport gets sevices from these monsters, it just puzzles me how the large aircraft can operate from such a small runway. 7,535 x 148ft (2,297 x 45m). Especially being in such hot area of the world.

Anyone got any opinions on this?



Posts: 531
Joined: Sun May 20, 2001 9:14 pm

RE: 747's At St Maarten.

Sun Sep 15, 2002 5:58 pm


I've wondered the same myself, but I guess the planes aren't full to the max with passengers and cargo. Less weight means more performance!
Posts: 173
Joined: Mon Jun 10, 2002 8:29 pm

RE: 747's At St Maarten.

Sun Sep 15, 2002 6:14 pm


I know what your saying and I thought about the fact that the 747 would obviously not be full. However, due to the contitions in which those aircraft operate when flying out of Princess Juliana it still puzzles me how they manage to get off the ground, safely at least.

I travel back to Aberdeen in Scotland a few times every year. The runway length there is about 1860m (about 6200feet) long. Whenever we are landing there, whether it be an A319, 320, 737 or 757, the breaks are always slammed on as soon as we touch down and we taxi off at the very last exit of the runway. I know the runway length is slightly shorter at Aberdeen opposed to Princess Juliana, however temperatures are much more favourable to operate and a 737 is not quite a 747.

When we leave Aberdeen, even on a half full 757, the breaks are held until the engins have spooled up and we use up most of the runway on the departure. I find it hard to get my head round how a 747 300, can get airbourne and fly thousands of miles accross the atlantic, off of a runway just 2200m long. Those 747s and DC10s are bound to be pretty full of fuel and quite a few passengers, especially during the summer and the fact that they have to travel a few thousand miles.

Perhaphs those who have flown the route could let us know what the loads are like, and what it's like to land and depart from SXM........



RE: 747's At St Maarten.

Sun Sep 15, 2002 6:28 pm

Dear Chris -
At TNCM / SXM airport, the runway is 7,535 feet long...
Let us see the problem... for a Corsair 747-300...
Basic operating weight of aircraft approximately 172,000 kg...
Typical charter seating, this would be 530 passengers... Y class...
So passengers plus their baggage and catering = 53,000 kg...
Now our airplane has a ZFW zero fuel weight of 225,000 kg...
Let's see now how heavy we can takeoff with that runway...
Temperature probably near 30 degrees Celsius...
We will assume 5 knots wind and 20 flaps takeoff...
My chart (for JT9D-7Q engines, quite powerful) max T/O = 315,000 kg...
That means that we can take 90,000 kg of fuel...
(315,000 - 225,000 = 90,000 kg)... ok...
I want to land in Paris with at least 14,000 kg (reserves/alternate)...
Means I have 76,000 kg as available trip fuel...
SXM to Paris is a 8 hrs flight... to Amsterdam nearly 9 hrs...
With 76,000 kg we can fly only 6 hours and a few minutes...
Unless they require passengers to row part of the Atlantic...
So it is impossible... not a direct flight...
What is likely, for Air France, Corsair and KLM...
Coming from Paris or Amsterdam, direct flight to SXM
There they drop a few passengers, take a few...
Then they go to PTP (Guadeloupe) - KLM goes to Aruba or Curacao...
Drop a few more passengers, take a few more...
There it is a long runway, permitting the trip to Europe...
Advertisement is probably "no change of plane"... that is correct...
But there is a little stop for passengers going other places... and fuel...
What's new in DXB...? Long time since I was there...
I delivered A6-GDP to the Dubai Air Wing in SEP 2000...
That is the 747 cargo for the Sheik's race horses and RR cars...
Happy landings to you
(s) Skipper

Posts: 257
Joined: Tue May 08, 2001 7:35 pm

RE: 747's At St Maarten.

Sun Sep 15, 2002 7:04 pm

Glad to see you are back, Skipper!
Posts: 2115
Joined: Tue May 18, 1999 3:49 am

RE: 747's At St Maarten.

Sun Sep 15, 2002 9:54 pm

Hello B747skipper,

Good estimation: before it switched to A340-300s, Air France used to operate a CDG-SXM-SDQ-CDG triangle rotation. And now with the A340s is still difficult to have a decent take-off performance.

Best regards,
Alain Mengus
Air Transport Business
Posts: 998
Joined: Fri Mar 01, 2002 9:00 am

RE: 747's At St Maarten.

Sun Sep 15, 2002 11:21 pm

B747skipper, it's good to have you back on board!


RE: 747's At St Maarten.

Mon Sep 16, 2002 7:18 am

Dear forum friends -
one thing some of you need to realize... about runway length, is this...
on a cold day, see level, a nearly empty 747 could takeoff with a 4,000 or 4,500 feet long runway...
on a hot day, high elevation, i.e. Nairobi, Kenya, a heavy one need every centimeters or inches of the 13,500 feet runway there...
Once in my life, I landed a 747 in Santa Barbara, USA on a very short runway, airplane "C" check and new airline paint job... I think the runway is about 5,000 feet long... we stopped on half of the runway.. and 2 weeks later, we took off from there, no problem...
all airplanes are like that... weight, temperature and elevation...
on some very light weight 747, our Vref (landing speed) could be as low as 118 kias... but heavy takeoff, a VR (rotation) could be 181 kias...
(s) Skipper
Posts: 1254
Joined: Sat Sep 18, 1999 10:47 am

RE: 747's At St Maarten.

Tue Sep 17, 2002 8:48 am

I believe that is a typo in Airways. The runway is actually only 7,054 feet.
Posts: 1960
Joined: Tue Feb 06, 2001 5:56 pm

RE: 747's At St Maarten.

Tue Sep 17, 2002 5:16 pm

John: as far as I know the runway is 7535 ft, where do you get 7,054 feet from?

I just remember my two most B747-400 takeoffs (as passenger of course), both within about two weeks.

this was actually a ferry flight, there were about 200 passengers on board, very little cargo. And fuel for a 300nm trip. I dont think we used more than about 2 km of the runway, if even that much (Take off weight was about 230 tons if memory serves).

Nearly sold out flight (350 passengers), according to pilot "full cargo payload", noon departure in mid-august, about 30 - 35°C, 5200 nm flight to SFO. I think we had about 380-390 tons of takeoff mass (cannot remember). 1500ft airfield elevation. Take off roll was about 12000ft if not a little more (runway is 13,123).

What a difference.

Does the runway @ SXM have a gradient, and Skipper, I could not find any information how a gradient affects Takeoff distance required. Can you help me out? Good to have you back.


RE: 747's At St Maarten.

Wed Sep 18, 2002 9:39 am

Guten abend SailorOrion -
I see you are a student in aeronautics, so I will give you some technical data.
Transport airplanes certificated by FAR/JAR 25 are limited to runway gradients of +2% UPslope and -2% DOWNslope... the limits apply to 747...
Yes the gradient of a runway affects the takeoff (also landing)... fortunately our good friends at Jeppesen Gmbh publish "runway analysis" tailored to our airplanes and operation, these runway analysis are published for each airport we go to and runways we can use... so takes a minute to figure maximum weight we can take off... temperature, wind and runway gradients are already included for us in these runway analysis...
I went to my 747-200/300 AOM (aircraft operating manual) to describe to you the effect of gradient... Gradient has effect on the V1 speed... we have to reduce V1 by 2 knots for each 1% runway downlope... and we can increase V1 by 1 knot for each 1% upslope... makes sense, for braking capability in case of an abort... other speeds, VR and V2 not affected...
As far as the runway "weight limitation" a 747 requiring a 12,000 feet runway for its weight (with a 0% gradient - level runway) could also takeoff at that same weight if it has 11,500 feet runway with a 1% downslope...
Same story for upslopes, if that airplane weight is requiring a 12,000 feet 0% gradient (level) runway, but faces a 1% gradient upslope, it is the same as having only 11,250 feet of runway, and they would have to reduce the weight of the aircraft...
I dont have EDDM runway data at end. but for EDDF as an example, my performance data for runway 07L and R says the gradient is +0.3% (up), but for runway 25L and R the gradient is -0.1% (down)... also runway 18, which we use most often for takeoff, is perfectly level... 0% gradient...
Nichts mehr zu zagen... wunderbar... anything more for you...?
Happy contrails -
(s) Skipper
Posts: 1960
Joined: Tue Feb 06, 2001 5:56 pm

RE: 747's At St Maarten.

Wed Sep 18, 2002 4:26 pm

Hey Skipper, nice German, and welcome to my respected users list  Smile

In case you are interested, here is the data for EDDM:

runways 08R and 08L have -0.1° (-0.17%), and runways 26R and 26L have +0.1° (+0.17%) slope. (both runways are 13,123 ft * 197 ft, 4000m * 60m, Concrete with a PCN of 090RAWT)

Actually I have a question:
Let's take my above example: a B744, 390 tons, lets say ISA+31°F, 1500 ft airport elevation, no wind. I know she can get off the ground within the 13,123 ft. My question is: As far as I know, the Accelerate-Stop distance cannot be greater than 13,123 ft, right? (the is no overrun length whatsoever). In this case, what would be the Takeoff Distance (and Run) required? It's easy to say "we used up ALL of the runway", but distances are very hard to estimate at these speeds, especially looking sideways through a smallish window with little reference outside. How much runway length do u have remaining when reaching V1 about? Does the Center of gravity position count in the Vr speed (theoretically it does, but I don't know whether the influence is big enough to really make a difference)


RE: 747's At St Maarten.

Wed Sep 18, 2002 10:26 pm

Dear SailorOrion -
This is all theory here, obviously you probably know some of it, as I can read by the way you write - such as accelerate-stop distance - or stopway...
The "FAR/JAR 25" takeoff distance is the greatest of 3 measurements -
(1) the "all engine takeoff distance" to 35 feet height + 15%...
(2) the "accelerate-stop distance" - accelerate with all engines to V1, loss of an engine, and stop the airplanes using brakes and spoilers only (no reversers are accounted for)...
(3) the "engine out takeoff distance" - accelerate with all engines to V1, loss of the most critical engine (outboard engine 1 or 4 for the 747), continue the takeoff to the 35 feet height, where V2 speed is achieved and gear is retracted...
Yes you are correct about the CG (the most rearward CG limit would be the most critical, this for minimum control speed reasons), but by chance the speeds V1, VR and V2 are (at and/or) above minimum control speed, V1 being never less than VmcG, and VR/V2 are above VmcA...
The British even have a more conservative way to compute VmcG than the FAR/JAR standard, they include a crosswind factor as well which would make the VmcG a little higher, since your flight controls (rudder) has to compensate for minimum control speed AND crosswind combined...
Now, your question was also "how much runway you use to V1..." - well - this is not really "known"... on a lightweight takeoff we use very little runway to pass V1, could be at 130 knots... on a heavy takeoff could be at or near 170 knots, probably some two thirds of the runway... say 8,000 or even 10,000 feet to get to V1... heavy weight we often "rotate" near the end...
You probably realize that "aircraft performance" is a hell of a long subject, dont ask me too many questions, or I will revenge myself by writing 200 pages about it...  Wink/being sarcastic I often teach in classrooms or simulators, and performance is my favorite subject... dont tempt me...
(s) Skipper

Posts: 1960
Joined: Tue Feb 06, 2001 5:56 pm

RE: 747's At St Maarten.

Wed Sep 18, 2002 10:57 pm

hehe... ok

I wrote an exam about aircraft performance myself last week, however, we dealt almost exclusively with 'air-performace', and almost nothing about field performace was said.

Thanks for helping  Smile


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