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Could A 737NG Land At Dutch Harbor?  
User currently offlineMozart From Luxembourg, joined Aug 2003, 2152 posts, RR: 13
Posted (7 years 4 months 2 weeks 3 days 10 hours ago) and read 4203 times:

I know that the 737-200 services to PADU were ended some time ago and replaced by SF3s on that route. AFAIK, this is because the frequent bad weather reduced the reliability of that route whilst operated by B732.

I know that PADU suffers not only from bad weather but also from a short runway, difficult terrain and maybe some other challenge.

Now I have a hypothetical question: could that airport with its "challenges" other than weather be served by a 737NG, for instance the 737-600 or 737-700, with the same payload that the 732 used to transport? Surely they aren't as heavy as the 738 or 739, so that could work, couldn't it? I am looking at it purely from a performance/weight vs. field/terrain aspect. I am not considering factors such as "737NG isn't combi like the AS 732 used to be" and "AS doesn't have the planes" - I only want to know about the performance metrics making this possible or impossible.

I post this in the tech/ops forum because I hope for some experts in the field of 737 performance to enlighten me a bit.

Thanks

Chris

PS: Probably some test pilots could land the plane there and get it out again - however, my question relates to normal commercial airline operation.

22 replies: All unread, jump to last
 
User currently offlineMiamiair From , joined Dec 1969, posts, RR:
Reply 1, posted (7 years 4 months 2 weeks 3 days 6 hours ago) and read 4157 times:

IMO you could. Be very load limited. Boeing came out with a modified B738 for GOL, so that they could operate out of Rio's Santons Dumont airport (SDU). SDU's runways are: 02R/20L 4,341 ft. and 02L/20R 4,134 feet.

DUT is 3,900 feet.


User currently offlineL-188 From United States of America, joined Jul 1999, 29705 posts, RR: 59
Reply 2, posted (7 years 4 months 2 weeks 3 days ago) and read 4087 times:

Probably once.

Dut has only 3900 to play with.



OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
User currently offlineATCT From United States of America, joined Mar 2001, 2223 posts, RR: 39
Reply 3, posted (7 years 4 months 2 weeks 2 days 21 hours ago) and read 4022 times:

Eh thats pretty tight. Doable by the books probably, but still thats VERY tight.


ATCT



"The way to get started is to quit talking and begin doing." - Walt Disney
User currently offlineCurmudgeon From Australia, joined Oct 2006, 695 posts, RR: 22
Reply 4, posted (7 years 4 months 2 weeks 2 days 19 hours ago) and read 3985 times:

Possibly with a -600, with no payload, no rain, no hills. The NG is a poor
runway performer compared to the -200, and the extra mass translates to poorer braking performance, among other things. (Braking becoming critical in the accelerate/stop distance case) (I think that a change in the FAR's dealing with V1 + 2 seconds delay is applicable to the NG, so that would be a deal breaker as well)



Jets are for kids
User currently offlineBingo From United States of America, joined Nov 2006, 359 posts, RR: 0
Reply 5, posted (7 years 4 months 2 weeks 2 days 17 hours ago) and read 3963 times:

Depends on how loaded it is and how bad the weather is, but I think its possible...
http://www.boeing.com/news/releases/2006/q3/060729a_nr.html


User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 6, posted (7 years 4 months 2 weeks 2 days 15 hours ago) and read 3951 times:

Quoting Miamiair (Reply 1):
IMO you could. Be very load limited



Quoting Curmudgeon (Reply 4):
Possibly with a -600, with no payload, no rain, no hills. The NG is a poor
runway performer compared to the -200, and the extra mass translates to poorer braking performance, among other things. (Braking becoming critical in the accelerate/stop distance case) (I think that a change in the FAR's dealing with V1 + 2 seconds delay is applicable to the NG, so that would be a deal breaker as well)

Baloney on both of the above.

A 737-700 has a MGTOW of around 155000 lbs. A 300 or 500's MGTOWs are around 130000 to 135000. So a classic (or 200) has a greatly reduced payload due to the severity of the Dutch Harbor airport, but a -700 will certainly carry the 155/135 ratio of payload... in other words, it will carry about 15% more payload than those a/c in the same atmospheric conditions, and probably a bit more.

How an airline certifies a type of a/c, and then the subtypes, varies airline by airline.


User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 7, posted (7 years 4 months 2 weeks 2 days 15 hours ago) and read 3944 times:

Quoting L-188 (Reply 2):

Dut has only 3900 to play with.

Let's wait a while and see how long it takes someone to get out the book and look up the distances...I bet that would take quite a long time, so I'll do it. From the book:

a -500 at 110000 lbs landing weight:

Max manual braking distance at Flaps 40: --> 2850 feet.

a -700 at 110000 lbs landing weight: (all other factors the same)

Max manual braking dist at Flaps 40: --> 2750 feet.

an -800 at 140000 lbs landing weight:

Max manual braking distance at Flaps 40: --> 3118 feet.

an -800 at 110000 lbs landing weight:

Max manual braking distance at Flaps 40: --> 3118- 405' (30000 lb diff correction) = 2713 feet.


User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 8, posted (7 years 4 months 2 weeks 2 days 14 hours ago) and read 3941 times:

Take off too?

Ok, what the heck. We get V speeds, not distance, out of the book. Since take off distances are proportional to V speeds, that is sufficient:

For a -500 at 110000 lbs, V1 and Vr are 129 and 131 kts respectively.

For a -700 at 110000 lbs, V1 and Vr are 113 and 115 kts respectively.

I would consider this question answered. An NG in Dutch will carry more payload in and out than a 2/3/4/500, or the same amount within even shorter field constraints. The NGs are evolutionary, and are more capable a/c than the classics...


User currently offlineCurmudgeon From Australia, joined Oct 2006, 695 posts, RR: 22
Reply 9, posted (7 years 4 months 2 weeks 2 days 14 hours ago) and read 3933 times:

Wrong. Every time you go up the models the runway required increases. The empty weight goes up with each model, so either more pavement or less payload is required. Also, airlines don't get any latitude in calculating FAR 25 field length requirements. Or obstacle clearance surveys, either. Having operated -200's into a 4300' runway, I can assure you that schedule reliability is poor owing to runway contamination/wet conditions.

3900' rwy is the minimum at the following weights: (Min stopping distance with maximum manual brakes, normal touchdown with max reverse thrust. Distance factored 66% per FAR requirements)(Rwy dry)

-300/-400 = 88,000 lbs

-800 = 90,200 lbs

These numbers were derived from an actual, current Boeing QRH for these aircraft types, and are approximate owing to the coarse nature of the data presentation. Take-off numbers would be worse. Note also that these numbers would allow zero payload using typical operating weights on the classic, and would be not achievable with typical-800 operating weights.



Jets are for kids
User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 10, posted (7 years 4 months 2 weeks 2 days 5 hours ago) and read 3861 times:

What? Uhh... the numbers I provided are right out of the book.

Quoting Curmudgeon (Reply 9):
The empty weight goes up with each model, so either more pavement or less payload is required.

Again...all I can say is "uuhhh, what?" Installed thrust and braking capability goes up with each model as well...which is why I provided the takeoff V speeds, again right out of the BOOK.

Quoting Curmudgeon (Reply 9):
3900' rwy is the minimum at the following weights: (Min stopping distance with maximum manual brakes, normal touchdown with max reverse thrust. Distance factored 66% per FAR requirements)(Rwy dry)

-300/-400 = 88,000 lbs

-800 = 90,200 lbs

What kind of weights are you providing? The OEW of an -800 is around 92000 lbs!!!

Quoting Curmudgeon (Reply 9):
These numbers were derived from an actual, current Boeing QRH for these aircraft types

I can assure you the #s I provided were. Know what I think? I think you are trying to extrapoloate data from a -200, or 300/400 manual, which would not be valid for the NGs, again, due to the fact that you aren't even in the ball park for an -800 with the 90200 number. Also, you didn't provide numbers for the -700, which would be the most logical choice for the application.

Oh yeah.... Just 1 more small issue that I have a problem with here, relating to the validity of your numbers.

Quoting Curmudgeon (Reply 9):
These numbers were derived from an actual, current Boeing QRH for these aircraft types

There are at least 2 QRHs for the 737 at the moment. One for the 3/4/5s, and one for the NG... so no, I don't put validiity in you numbers.

An NG (particularly a -700) would perform better in every regime as compared to a -200 in any airport, adn that applies to Dutch Harbor as well.


User currently offlineMandala499 From Indonesia, joined Aug 2001, 6590 posts, RR: 75
Reply 11, posted (7 years 4 months 2 weeks 2 days 1 hour ago) and read 3818 times:

OK, I'm pulling the book out...
PADU: 3900ft... I have no other info on PADU.

Using ball park performance figures from Boeing Airfield Compatibility (whatever it's called)...

Basic Data (all data using highest thrust rating):
732A OEW = 65300lbs
735 OEW = 69030lbs
733 OEW = 72540lbs
736 OEW = 80,200lbs
737 OEW = 83000lbs

TOW (FAR) (max allowable T/O flap)
732(15) = 96000lbs (PLD+F = 30700lbs)
732(17) = 98000lbs (PLD+F = 32700lbs)
732(17R) = 99000lbs (PLD+F = 33700lbs)
735 = 101000lbs (PLD+F = 31970lbs)
733 = 107000lbs (PLD+F = 34460lbs)
736 = 117000lbs - 124000lbs (PLD+F = 36800lbs - 43800lbs
737 = 116000lbs - 126000lbs (PLD+F = 33000lbs - 43000lbs)

LW (FAR)
732 = F30 = 93000lbs, F40 = 97000lbs (PLD+F = 27700lbs / 31700lbs)
735 = F30 = 90000lbs, F40 = 94000lbs (PLD+F = 20970lbs / 24970lbs)
733 = F30 = 93000lbs, F40 = 95000lbs (PLD+F = 20460lbs / 22460lbs)
736 = F30 = 103000lbs, F40 = 115000lbs (PLD+F = 22800lbs / 34800lbs
737 = F30 = 103000lbs, F40 = 115000lbs (PLD+F = 20000lbs / 32000lbs)

Using effective runway landing limit (ie: Runway length beyond touchdown point, plus 1000ft, we don't wanna clip the fence do we?)

Landing limits (No wind, dry, antiskid operative, auto ground spoiler operative) for 4000ft:
732A Flap30 = 80000lbs, Flap40= 84000lbs (Source: Mandala Airlines)
735 Flap30 = 92000lbs, Flap40 = 96200lbs (Source: Continental)
733 Flap30 = 94200lbs, Flap40 = 98100lbs (Source: Continental)
737 Flap30 = 104900lbs, Flap40 = 107100lbs (Source: Continental)
738 Flap30 = 9600lbs, Flap40 = 104100lbs (Source: Continental)

So, at PADU, the 600 would be the best performer... the 700 looses out on the landing performance, and the -200 fares better than the landing over the classics...

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 12, posted (7 years 4 months 2 weeks 1 day 22 hours ago) and read 3782 times:

Quoting Mandala499 (Reply 11):
OK, I'm pulling the book out...

What book are you using? Mine was the QRH; since OEWs are tail number specific I'm not sure what your source is.

Quoting Mandala499 (Reply 11):
TOW (FAR) (max allowable T/O flap)
732(15) = 96000lbs (PLD+F = 30700lbs)
732(17) = 98000lbs (PLD+F = 32700lbs)
732(17R) = 99000lbs (PLD+F = 33700lbs)
735 = 101000lbs (PLD+F = 31970lbs)
733 = 107000lbs (PLD+F = 34460lbs)
736 = 117000lbs - 124000lbs (PLD+F = 36800lbs - 43800lbs
737 = 116000lbs - 126000lbs (PLD+F = 33000lbs - 43000lbs)

What is PLD, and PLD + F? What TOW are you specifing? A landing distance chart is entered at a landing weight, and the modified for various factors, whcih produces a landing distance.

Quoting Mandala499 (Reply 11):
Using effective runway landing limit (ie: Runway length beyond touchdown point, plus 1000ft, we don't wanna clip the fence do we?)

What exactly is "effective runway landing limit"?

Quoting Mandala499 (Reply 11):
Landing limits (No wind, dry, antiskid operative, auto ground spoiler operative) for 4000ft:

What about brake setting???

Quoting Mandala499 (Reply 11):
the 600 would be the best performer... the 700 looses out on the landing performance, and the -200 fares better than the landing over the classics...

I agree; intuitively the smallest of the NGs would have the best short field capability of the entire lot. I have no -600 data, so I used the -700. Since I don't understand several components in your post, I don't see how you arrived your conclusion. From the data I provided on landing distance and V speeds, it is easy to see the -700 is superior to the classics. Further, since the -700 is superior, it follows that the lightest of the NGs woud be the best short field performer (the -600). Note an -800, landing with (110000-95000) = 15000 lbs of load. Of that, assume it lands with 5000 lbs of fuel, therefore 10000 lb of payload, and gets it stopped in the shortest distance of 2713 feet. The V speeds for t/o for the -800, however, are higher than the -700 and I assume -600 at the same weight, therefore I'd call the 6/7 better short field a/c.

The 6/7/8 would all out perform the -200 carrying the same payload from Dutch Harbor or any other airport.

[Edited 2006-12-07 22:26:08]

[Edited 2006-12-07 22:32:49]

[Edited 2006-12-07 22:47:18]

[Edited 2006-12-07 22:48:15]

User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 13, posted (7 years 4 months 2 weeks 1 day 22 hours ago) and read 3775 times:

Quoting EssentialPowr (Reply 10):

What kind of weights are you providing? The OEW of an -800 is around 92000 lbs!!!

Closer to 95000 lbs upon further inspection. It is invalid to try to deduce NG numbers from a -200 or 3/4/5 QRH. Interpolation (or "derrived" numbers) is not valid, as the NGs have better acceleration (accel and decel) capability.

That's what the QRH is for, and you have to have the right one for the specific a/c, and when you do, the question is easily answered.

cheers

[Edited 2006-12-07 22:38:18]

User currently offlineMandala499 From Indonesia, joined Aug 2001, 6590 posts, RR: 75
Reply 14, posted (7 years 4 months 2 weeks 1 day 8 hours ago) and read 3674 times:

EssentialPowr,

Quoting EssentialPowr (Reply 12):
What book are you using? Mine was the QRH; since OEWs are tail number specific I'm not sure what your source is.

The figures come out from Boeing's Airport compatibility documents for each of the 737 versions mentioned. Which under section3 of each aircraft type in the document series include the FAR (and for NG, the JAA) Take Off Runway Requirements as well as the FAR Landing Runway Length Requirements. Note: this does not include Climb Limits ! So some numbers require a ridiculous t/o flap setting of 25 which doesn't make it a good 2nd segment climber.

The docs are:
D6-58325 April 1982 for the 737-200 (with figures taken out of the 732Advanced, not the 732Basic)
D6-58325-2 Sep 1988 for the 737 classics (-300/400/500)
D6-58325-3 Dec 2001 for the 737NG (no winglets)

Those figures include FAR runway and landing requirements (which include obstacle clearances) and not actual landing/take off rolls. Those figures are then cross checked with:

For the 732, it's Boeing Flight Planning and Performance Manual 737-200Adv JT8D-17, Doc D632A002-PZ016 Dec03, 1999.

The 733/5/7 figures come from Continental's 737 Flight Manual Rev 11/15/02 someone forwarded to me. Figures were taken out of Section 5 - Flight Performance. The Manual coveres 733/5/7/8/9.

The numbers are "generally" within accepted deviations for route commercial planning purposes. (ie: minor differences between the two sources)

All the figures I picked are based on ISA, dry runway, no wind, no slope, hard surface assumptions.

Quoting EssentialPowr (Reply 12):
What is PLD, and PLD + F? What TOW are you specifing? A landing distance chart is entered at a landing weight, and the modified for various factors, whcih produces a landing distance.

The TOW and LW numbers come out of the Airport compatibility documents... again, cross checked with the 732/3/5/7 on the other docs. The weight figures are obtained by looking at available runway length, and seeing the weight limit for that length (with appropriate flap setting for the landing). Again, the figures I used are using the highest engine thrust version available for the take off figures.

As the OEWs are based on actual tail numbers, for route planning purposes we use the generic manufacturer's typical OEW (Weight of structure, powerplant, furnishing systems, unusable fuel and other unusable propulsion agents, and other items of equipment that are considered an integral part of a particular airplane configuration. Also included are certain standard items, personnel, equipment, and supplies necessary for full operations, excluding usable fuel and payload.).

What does not change are the TOW and LWs for the runway in question. From the TOWs and LWs, subtract that by the OEW and you get Payload (PLD) + Fuel (F) it can carry into and out of the runway. PLD + F is the designation we use for route planning and feasibility.

Quoting EssentialPowr (Reply 12):
What about brake setting???

Brake setting not mentioned as the Stopping Distances with Autobrakes or Stopping Distances are not supplied and is an advisory piece of info.

Some figures come to 4000ft as minimum length. 3900 figures aren't that far of, this is not a good practice for operational purposes, but sufficient for discussion purposes. The figures you used seem to be the actual landing roll. You should add another 1000ft on top of the figures you supplied in reply #7 to allow for effective obstacle clearance on the approach.

Quoting EssentialPowr (Reply 12):
What exactly is "effective runway landing limit"?

The effective runway landing limit =
The Effective Runway Landing Length is the available length used to calculate the aircraft maximum landing weights. This length is the physical length (as published by Jeppesen) corrected for threshold displacement, obstacle clearance requirements or glide slope displacement. The Effective Runway Landing Length for each of the runways for company airports is listed in runway analysis. For runways that have been temporarily shortened, consult the appropriate NOTAMS. If unable to contact Load Planning, Effective Runway Landing Length can be determined by the crew as the lesser of:
1. Jeppesen Published Runway Length (page 10-9).
2. Runway Length beyond Glide Slope touchdown point, plus 1000 feet.
3. Shortened Length indicated by current NOTAM.


Interestingly... a 738 with 3900ft:
FAR TO limit is 120000lbs at the 24.2klbs engines, and 123000lbs on the 26.3klbs engines, 127000lbs at the 27.3klbs engines.

FAR Landing Flap limit is 103000lbs on flap 40 and not possible on flap30 (at 100000lbs it already requires 4200ft).

Quoting EssentialPowr (Reply 13):
Closer to 95000 lbs upon further inspection.

Errr well , 738 OEW is somewhere near 91,300lbs (see source above)... 95000lbs sounds like it has had a few more features added to it!

All in all... Pavement Strength requirements aside, Yes, I'd take an NG in and out (600 or 700) of PADU, and then a 732 over any classic! (Pity the NG is a hog when it comes to pavement strength requirements... since a lot of the times, I have to assess them going to some really marginal strength airports!)

Mandala499

[Edited 2006-12-08 13:04:05]

[Edited 2006-12-08 13:06:50]


When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineCurmudgeon From Australia, joined Oct 2006, 695 posts, RR: 22
Reply 15, posted (7 years 4 months 2 weeks 1 day 7 hours ago) and read 3660 times:

Gentlemen, the books that I derived my numbers from are the actual, current factory QRH. One copy for the -300/400, AND one copy for the -800.

I made the point that the weights the -800 could operate were theoretical, because they were above the operating weight empty.

The way that my QRH reads is a reference weight is given, and a minimum rwy length (landing). I subtracted the increments listed until I got down to the length available (+ FAR required factors as I noted). That this process then yields a weight below the lowest BOWE proves my point.(about the -800, and probably the -700). If any NG could do it, the -600 would be the only candidate.

While the 737-200 has the lowest thrust of all the models, it also has the lowest weight, which allows some payload, and some RTO capability.



Jets are for kids
User currently offlineMandala499 From Indonesia, joined Aug 2001, 6590 posts, RR: 75
Reply 16, posted (7 years 4 months 2 weeks 1 day 7 hours ago) and read 3652 times:

Curmudgeon,
Well, the 738 would be a dead duck in this situation anyways... Even using the factory numbers, it's a dismal load... roughly 5 tons payload and fuel on landing, 12 tons on take off... it's already commercially a no go. The 700 being able to carry 14 tons of fuel and payload on landing is a bit better (130 pax with no overweight luggage and 2 tons of fuel) with the take off in the 18 tons P + F, 6 tons of fuel doesn't get you anywhere much, but then, what's the domestic reserves requirement in the US?

But yes, the 600 would be best for this, the 700 would be wasting the airframe in terms of carrying the dead weight for a smaller revenue potential.

At least we all come to the conclusion that the 300/500 wouldn't be suitable for this task...

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 17, posted (7 years 4 months 2 weeks 1 day 2 hours ago) and read 3625 times:

Quoting Mandala499 (Reply 14):
The figures come out from Boeing's Airport compatibility documents for each of the 737 versions mentioned. Which under section3 of each aircraft type in the document series include the FAR (and for NG, the JAA) Take Off Runway Requirements as well as the FAR Landing Runway Length Requirements.

The fundamental flaw in using Compatability Docs is that they are not dispatch performance numbers, and are therefore much more approximate than dispatch numbers. In flight, the legal and most accurate ref in the QRH, which is why I simply looked up the landing distance.

As a subset to this, Compatability Docs are extremely general and do not correct for performance specifics on a per operator basis.



Quoting Mandala499 (Reply 14):
The Effective Runway Landing Length is the available length used to calculate the aircraft maximum landing weights. This length is the physical length (as published by Jeppesen) corrected for threshold displacement, obstacle clearance requirements or glide slope displacement. The Effective Runway Landing Length for each of the runways for company airports is listed in runway analysis.

For a 121 op, runway analysis is unique to operator and subtype, per the operators op specs.

Quoting Mandala499 (Reply 14):
Brake setting not mentioned as the Stopping Distances with Autobrakes or Stopping Distances are not supplied and is an advisory piece of info.

This is the single largest flaw in your use of Runway Comp #s. Not specifing a brake setting is as significant as not specifying a flap position.

You correctly deduced the -600 would have the best perf (takeoff and landing), which I agreed to w/o access to a -600 QRH but looking at the -700/-800 QRH. Following that would be the -700 and -800, all would exceed the payload capability of the -200 in both takeoff and landing regimes.

[Edited 2006-12-08 18:38:58]

User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 18, posted (7 years 4 months 2 weeks 1 day 2 hours ago) and read 3614 times:

Quoting Curmudgeon (Reply 15):
Gentlemen, the books that I derived my numbers from are the actual, current factory QRH. One copy for the -300/400, AND one copy for the -800.

Then why didn't you just use the landing distance tables, and publish a landing distance and takeoff V speeds?

Here's a rough thrust to weight ratio for a -200:

128600MGTOW/34000lbs thrust = 3.78 lbs of a/c per lb of thrust.

For the -600:

145500 MGTOW/ 45400 lbs thrust = 3.20lbs of a/c per lb of thrust.

Quoting Curmudgeon (Reply 15):
While the 737-200 has the lowest thrust of all the models, it also has the lowest weight, which allows some payload, and some RTO capability.

Does a thrust to weight ratio now make sense? The 6/7/8 can the same payload from a shorter distance, and land it in a shorter distance. Just because Alaska flew -200 in there doesn't mean that made it the best performer. They probably used older a/c due in Dutch Harbor due to the rock/fod threat and more primitive conditions.


User currently offlineMandala499 From Indonesia, joined Aug 2001, 6590 posts, RR: 75
Reply 19, posted (7 years 4 months 2 weeks 15 hours ago) and read 3530 times:

EssentialPowr,
Indeed those numbers are not for despatch. They are for initial route commercial analysis, and yes, the QRH is more accurate. But I am not looking at the dispatch aspects of the PADU, and don't intend to claim so. I understand there are flaws by using those documents, but on a commercial basis (not an operational one), I would disagree if I have to dismiss them. Through experience, I have ended up with "if the commercial basis make it operationally unattractive (unless marginal), I don't care what the ops guys says, it's a No-Go"... and if otherwise, I'd let the ops guys take a deeper look (which is where your analysis come in). This may sound utterly basic, but believe me, there are operators who don't even look at this and then Ops come out screaming "it's impossible" when it's almost too late (ie: the week or even a few days before they were to open the route!)... it has happened. I guess some companies I've seen have screwed up information flows!  Smile

Those Compatibility Docs are general, and has stated "Check with Airline Operator for detailed perfomance" or something like that. Hence, one airline may be able to operate in and out of PADU while another cannot, despite having the same aircraft type and engine. Since we're not talking about a particular operator, I used the general one. If I read Continental's Flight Manual correctly, PADU would not be "company legal" to operate into (unless the QRH specified a 3900' or lower figure), but it could be legal for another.

The Comp # are just there to generally say it's possible, but there are other documents (such as those you have) to see how it can/cannot be done.

What I am now interested in, is that, why does the Boeing 732 FCOM specify the Brake Stopping distances as "Advisory Information" ?

Back to your stopping distance figures, whilst those numbers you provided give a better load for landing into PADU for each type we mentioned, my concern is, are those just the landing roll on the ground distances? The runway is only 3900', and one should always allow a 500 - 1000ft (I prefer the 1000ft for a safety margin) distance above that (I don't want planes clipping the fence) to allow for a safe approach. I don't want 737 pilots to land right on the threshold... coz the insurers and regulators will surely give me frequent visits.

Given the above, I really do not feel comfortable with 738's 140,000lbs stopping distance figure, 3118ft, slap a 1000ft from threshold touchdown and we're already 218ft in the water/mud/overrun zone on the numbers.

As general as the numbers I provided from the Compatibility docs, the numbers you provided are, actually would/should actually yield similar end result, in particular, the -700 figures... 115000lbs flap 50 for 3900ft... which should translate to 2900ft landing roll at max manual braking... your 110000lbs give the 2750ft landing roll... Again for the -800, 103000lbs for a 3900ft runway, hence 2900ft landing roll, your figures for 110000lbs gives a 2713ft landing roll...

So, those Airport Compatibility FAR Landing Distance docs are based on generic versions of the aircraft, taking into a 1000ft from threshold touchdown, and the conditions you used for your stopping distance numbers, the results are "generally similar". I've had arguments on this stopping distance vs runway requirements before (which resulted in the management consulting the ops guys, who told management to axe the proposed route on the same grounds).

Hence,

Quoting EssentialPowr (Reply 17):
Following that would be the -700 and -800, all would exceed the payload capability of the -200 in both takeoff and landing regimes.

I would disagree on the part of the -800. The -200 can carry 33700lbs of fuel + payload out of PADU and 31700lbs into PADU while the -800 can carry 35700lbs of payload and fuel out, BUT only 11700lbs into PADU... Well, if its a 15 minute flight to the destination, I'd reconsider though  Smile

Given this, I wouldn't want to operate the -800 into PADU at any circumstance... But the -600 and -700 I'd take there anyday... RTB-ing to PADU would be ugly on the -800! (Yes, us commercial guys do think about that eventuality!)

Quoting EssentialPowr (Reply 18):
Does a thrust to weight ratio now make sense? The 6/7/8 can the same payload from a shorter distance, and land it in a shorter distance. Just because Alaska flew -200 in there doesn't mean that made it the best performer. They probably used older a/c due in Dutch Harbor due to the rock/fod threat and more primitive conditions.

Well, we know the differenyt wing and brakes also makes a difference, and the 200 is different with both... which gives the different V speeds which can make a difference between feasibility and not.

As for why Alaska use the 200 instead of the 700, I'd have to ask for the pavement strength of PADU... NGs tend loose out on this front on marginal strength airports. Again, on a commercial planning basis, if I remember correctly, I've seen places where a -300 can carry more than a -600 on this basis... strange eh?

Its a pity that discussions such as the one we're having here does not always happen at airlines. These kinds of talk should happen before the company even announces the route, and some have done so without consulting the ops (with the exception of seeing the spare capacity/utility)... I guess some companies just love to waste money (and I hope none of us are in those companies).

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 20, posted (7 years 4 months 2 weeks 14 hours ago) and read 3525 times:

Quoting Mandala499 (Reply 19):
Indeed those numbers are not for despatch. They are for initial route commercial analysis, and yes, the QRH is more accurate

Okay, so now we discuss the validity of those #s in answering the question, which is why a QRH is certainly much more accurate in answering the question.

Quoting Mandala499 (Reply 19):
If I read Continental's Flight Manual correctly, PADU would not be "company legal" to operate into (unless the QRH specified a 3900' or lower figure), but it could be legal for another.

correct.

Quoting Mandala499 (Reply 19):
What I am now interested in, is that, why does the Boeing 732 FCOM specify the Brake Stopping distances as "Advisory Information" ?

Probably b/c at the time it was published, the dispatch perf numbers were controlling. That concept has changed.

Quoting Mandala499 (Reply 19):

Given this, I wouldn't want to operate the -800 into PADU at any circumstance... But the -600 and -700 I'd take there anyday... RTB-ing to PADU would be ugly on the -800! (Yes, us commercial guys do think about that eventuality!)

Concur. But as I said, the -800 (in particular here) is still better than any older generation 737 b/c it will carry more out than it can deliver. But wait a minute. What does happen in the engine out scenario? No fool returns to a 3900 ft runway. ANY of the NGs can carry the same payload as the -200, and fly back to another airport a LONG way away. Not so in the -200.

Quoting Mandala499 (Reply 19):
are those just the landing roll on the ground distances? The runway is only 3900', and one should always allow a 500 - 1000ft (I prefer the 1000ft for a safety margin) distance above that (I don't want planes clipping the fence) to allow for a safe approach.

Neg. The numbers I provided are from a QRH. It is designed to accomodate the above eventualities, so that crews can get an number and fly the a/c. The notes on the QRH are:

1. includes 1000 feet of air distance
2. 10 kt max tailwind
3. approach speed is Vref +5 kts.

Quoting Mandala499 (Reply 19):
Well, we know the differenyt wing and brakes also makes a difference, and the 200 is different with both... which gives the different V speeds which can make a difference between feasibility and not.

Right. And the -200 is proportionately inferior in both the accel and decel case. The NGs takeoff, and stop, proportionately better than the -200.

Quoting Mandala499 (Reply 19):
Given the above, I really do not feel comfortable with 738's 140,000lbs stopping distance figure, 3118ft, slap a 1000ft from threshold touchdown and we're already 218ft in the water/mud/overrun zone on the numbers.

What inept dispatcher would sign off on that? As I said, land an -800 at 110000lbs, and it carries 15000 lbs of load to a stop in 2713 feet - better than the 3/5 or 7 (maybe the 6??). Would I want to do it? No way, but the question was about an NG, at Dutch Harbor, and I told the forum from the outset, that given the same payload as the -200, the 6/7/8 would all use less runway for takeoff or landing, and that is indisputable. Alaska isn't flying any 737s there any more, and an NG is probably misuse of the asset, which may solve the question as to why the -200s were there in the first place.

Quoting Mandala499 (Reply 19):
As for why Alaska use the 200 instead of the 700, I'd have to ask for the pavement strength of PADU... NGs tend loose out on this front on marginal strength airports.

Not even a valid argument, unless the -200s had gravel kits on them... Ground loading is a function of mass, an if all a/c are carrying the same payload, and due to the greater width of the NG tires, the diff is negligible.

Quoting Mandala499 (Reply 19):
I've seen places where a -300 can carry more than a -600 on this basis... strange eh?

Never heard of that; pls elaborate.

Nice chatting with you; I respect your input to a good thread.

[Edited 2006-12-09 06:25:31]

[Edited 2006-12-09 06:26:46]

[Edited 2006-12-09 06:29:36]

[Edited 2006-12-09 06:31:42]

User currently offlineLitz From United States of America, joined Dec 2003, 1753 posts, RR: 0
Reply 21, posted (7 years 4 months 2 weeks 3 hours ago) and read 3460 times:
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Just out of curiosity (and I'm still trying to interpret all the jargon in this thread) ... has anyone fired up a flightsim and actually tried this?

It's not reality of course, but it might be an interesting exercise ...

- litz


User currently offlineMozart From Luxembourg, joined Aug 2003, 2152 posts, RR: 13
Reply 22, posted (7 years 4 months 1 week 5 days 20 hours ago) and read 3369 times:

Quoting Litz (Reply 21):
Just out of curiosity (and I'm still trying to interpret all the jargon in this thread) ... has anyone fired up a flightsim and actually tried this?

It's not reality of course, but it might be an interesting exercise ...

- litz

 Big grin  Big grin I have... actually, I started this thread because I was planning to do a flight in FlightSim to PADU and one from PADU with my PMDG 737-700. I wanted to have an idea whether such a flight would be at least somewhat realistic.

From my Flightkeeper logbook, here are the data:

On the first flight, from PACD to PADU:

Payload 22,766 lbs
ZFW 105,766 lbs
Fuel 2,522 lbs
LAW 108,291 lbs
Touch down speed 108 KIAS with Flaps 40 (that was a tad slow, the FMC called for 119 KIAS)
Weather 30 Fahrenheit, Alt 28.84, Wind 106 @ 3

-> A breeze! No problem landing and stopping way ahead of the runway end whatsoever.

On the second flight, from PADU to PANC:

Payload 22,766 lbs
ZFW 105,766 lbs
Fuel 13,567 lbs (that left a huge reserve of more than 5,000 lbs at arrival)
TOW 119,336 lbs
Vr at 133 KIAS, Flaps 5
Weather 30 Fahrenheit, Alt 28.84, Wind 106 @ 3

-> I made it, but only just. There wasn't much left between my gear and the fence at the end of runway 12

So in the virtual world it works - but bear in mind the limited realism, even though the PMDG product is certainly one of the higher quality and more realistic ones.

Thanks for all the replies, it greatly enhanced the "learning" aspect of my flying.


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