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Weight Restrictions For B737-900ER/ 9 MAX  
User currently offlineeaa3 From United States of America, joined Sep 2007, 1015 posts, RR: 0
Posted (11 months 2 weeks 4 days 20 hours ago) and read 5978 times:

Icelandair ordered the B737-9 MAX for flights to North America. Obviously, for such a long flight Icelandair will want to take-off at MTOW, need a range of about 2500 nm. and in summer there will be hot days (90 degree weather). Furthermore, some of the airports they operate to (such as BOS) have a 10,000 ft runway. Plus, since KEF is in the middle of the Atlantic ocean the aircraft will need to have abnormally large reserves for an alternative.

My question is the following. For a B737-9 MAX: How serious will the weight restrictions be for a flight taking off on a hot day from BOS (at sea level), flying about 2500 nm. (with abnormally large reserves given GLA alternative) and from a 10,000 ft runway.

How would the A321 NEO perform? Would the B737-8 MAX be better?

Obviously, not all the information is available. However, the B737-900ER should suffice as an alternative.

34 replies: All unread, showing first 25:
 
User currently offlinethenoflyzone From Canada, joined Jan 2001, 2515 posts, RR: 11
Reply 1, posted (11 months 2 weeks 4 days 19 hours ago) and read 5936 times:

Firstly, BOS-KEF is 2097 nm. Max range of the B739ER is 3265nm with winglets and 2 aux tanks. The B737-9 MAX has even better range, 3595nm. So the 10,000ft runway should be plenty.

BTW, a MTOW B739ER in ISA conditions (15 C, no wind, etc) at sea level, needs roughly 3000m (9,843 ft) of runway. The B737-9 MAX will require a shorter runway, methinks, what with better engines, and ligher weights.

Thenoflyzone

[Edited 2013-10-17 14:16:56]


us Air Traffic Controllers have a good record, we haven't left one up there yet !!
User currently offlineeaa3 From United States of America, joined Sep 2007, 1015 posts, RR: 0
Reply 2, posted (11 months 2 weeks 4 days 19 hours ago) and read 5914 times:

Quoting thenoflyzone (Reply 1):
Firstly, BOS-KEF is 2097 nm, factor in the tailwind, and the plane is nowhere near MTOW. Max range of the B739ER is 3265nm with winglets and 2 aux tanks, which I'm sure Icelandair will get. So a BOS-KEF flight is nowhere near MTOW. So the 10,000ft runway should be plenty.

Boston is one of the closest destinations. Let's take Washington, for example. IAD is over 2500 nm away. Plus, they need to be able to fly to Glasgow, which is the alternative for KEF. I would think that they probably need to be fuelled up for 3,000 nm. There are often tailwinds but there may be days where they don't benefit from it.

The max range may be 3265 nm but I'm asking about take-off performance. I realize IAD has an 11,500 ft runway but there may be other destinations that they want to add.


User currently offlinethenoflyzone From Canada, joined Jan 2001, 2515 posts, RR: 11
Reply 3, posted (11 months 2 weeks 4 days 19 hours ago) and read 5895 times:

Quoting eaa3 (Reply 2):
Let's take Washington, for example. IAD

I dont see Icelandair putting the 737 MAX 9 on IAD-KEF, or any other route that is longer.

It will stick to YHZ, YYZ, JFK, EWR and BOS.

The 757 is and will remain the workhorse of Icelandair for some time to come. If they do put he 737 MAX 9 on long routes and they need to file an IFR alternate like GLA or wherever 700 nm away, expect a fuel stop in YHZ. That's all.

Even UA, DL and AA 757s across the pond westbound during the winter encounter fuel stops on occassion. S**t happens.

Quoting eaa3 (Reply 2):
but I'm asking about take-off performance

As i said, takeoff performance is not an issue with any airport that Icelandair serves with at least a 10,000ft runway, which in North America is all of them except YHZ. (and YHZ is only 1785nm from KEF, so it doesn't need a 10,000ft runway)

Thenoflyzone

[Edited 2013-10-17 14:31:36]


us Air Traffic Controllers have a good record, we haven't left one up there yet !!
User currently offlineeaa3 From United States of America, joined Sep 2007, 1015 posts, RR: 0
Reply 4, posted (11 months 2 weeks 4 days 18 hours ago) and read 5888 times:

Quoting thenoflyzone (Reply 3):
I dont see Icelandair putting the 737 MAX 9 on IAD-KEF, or any other route that is longer.

Actually, they plan to put the B737-9 on all routes apart from SEA, DEN and so forth. I mean they ordered 8 of them. So east coast destinations will be served with these planes, theoretically. I think they've miscalculated.


User currently offlineroseflyer From United States of America, joined Feb 2004, 9661 posts, RR: 52
Reply 5, posted (11 months 2 weeks 4 days 18 hours ago) and read 5843 times:

There are 4-5 other airports in Iceland with 5,000+ft runways in Iceland, so I’m not sure Glasgow needs to be an alternate for Keflavik.

Also, temperatures from the US aren’t as important because the winds only help on US-Iceland. Iceland is often north of the main jetstream, but it can help shorten flight time. US-KEF is usually shorter than KEF-US. Temperatures in KEF are never above 70F, so that helps.

BOS-KEF is no worse than BOS-LAX. IAD & MSP will be bigger challenges.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineViscount724 From Switzerland, joined Oct 2006, 25459 posts, RR: 22
Reply 6, posted (11 months 2 weeks 4 days 17 hours ago) and read 5824 times:

Quoting thenoflyzone (Reply 3):
As i said, takeoff performance is not an issue with any airport that Icelandair serves with at least a 10,000ft runway, which in North America is all of them except YHZ. (and YHZ is only 1785nm from KEF, so it doesn't need a 10,000ft runway)

Longest runway at YHZ is 10,500 feet. Extension of runway 05/23 from 8,800 to 10,000 opened for use almost a year ago, November 15, 2012.
http://www.cbc.ca/news/canada/nova-s...-runway-for-bigger-jets-1.1330018.

Press release on the official opening in January.
http://hiaa.ca/2013/01/extended-runw...-ushers-in-new-era-in-air-service/


User currently offlinethenoflyzone From Canada, joined Jan 2001, 2515 posts, RR: 11
Reply 7, posted (11 months 2 weeks 4 days 15 hours ago) and read 5773 times:

Quoting Viscount724 (Reply 6):
Longest runway at YHZ is 10,500 feet. Extension of runway 05/23 from 8,800 to 10,000 opened for use almost a year ago, November 15, 2012.

I'll be darned ! You learn something new everyday !

Thenoflyzone



us Air Traffic Controllers have a good record, we haven't left one up there yet !!
User currently offlineViscount724 From Switzerland, joined Oct 2006, 25459 posts, RR: 22
Reply 8, posted (11 months 2 weeks 4 days 13 hours ago) and read 5743 times:

Quoting Viscount724 (Reply 6):
Longest runway at YHZ is 10,500 feet. Extension of runway 05/23 from 8,800 to 10,000 opened for use almost a year ago, November 15, 2012.

Too late to edit. Should read ...from 8.800 to 10,500...


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17055 posts, RR: 67
Reply 9, posted (11 months 2 weeks 4 days 10 hours ago) and read 5671 times:

Quoting eaa3 (Thread starter):
Plus, since KEF is in the middle of the Atlantic ocean the aircraft will need to have abnormally large reserves for an alternative.
Quoting eaa3 (Reply 2):
Plus, they need to be able to fly to Glasgow, which is the alternative for KEF.

Rules like decision Point Procedure and Isolated Airport (AKA Island reserve) may apply. These cut the needed fuel significantly compared to standard "overland" rules.

If KEF is seen as an isolated airport, you wouldn't need an alternate. From memory you would need two hours of reserve fuel at cruise speeds, but not alternate fuel or final reserve.

Besides:

Quoting roseflyer (Reply 5):

There are 4-5 other airports in Iceland with 5,000+ft runways in Iceland, so I’m not sure Glasgow needs to be an alternate for Keflavik.
Quoting eaa3 (Reply 4):
I think they've miscalculated.

And I think that between Icelandair and Boeing they can probably find a few guys who know what they are doing.

[Edited 2013-10-17 23:14:02]


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineeaa3 From United States of America, joined Sep 2007, 1015 posts, RR: 0
Reply 10, posted (11 months 2 weeks 3 days 18 hours ago) and read 5468 times:

Quoting Starlionblue (Reply 9):
And I think that between Icelandair and Boeing they can probably find a few guys who know what they are doing.

Boeing has probably promised things regarding the B737-900 performance that didn't pan out as expected.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17055 posts, RR: 67
Reply 11, posted (11 months 2 weeks 3 days 13 hours ago) and read 5411 times:

Quoting eaa3 (Reply 10):
Quoting Starlionblue (Reply 9):
And I think that between Icelandair and Boeing they can probably find a few guys who know what they are doing.

Boeing has probably promised things regarding the B737-900 performance that didn't pan out as expected.

Granted, manufacturers have from time to time overpromised, but even in the MD-11 case we're talking a few percent fuel burn. What you're talking about are very gross miscalculations.

I would be astounded if Boeing had gotten it so wrong.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinesweair From Sweden, joined Nov 2011, 1824 posts, RR: 0
Reply 12, posted (11 months 2 weeks 3 days 9 hours ago) and read 5360 times:

The 739 will take a payload hit on the longer routes, this is the sad part of it being a 757R in Boeings mind. It also is very limited on hot and high take offs.. The 757 still rules the 3000nm+ routes despite being very old.

User currently offlinemham001 From United States of America, joined Feb 2005, 3660 posts, RR: 3
Reply 13, posted (11 months 2 weeks 2 days 18 hours ago) and read 5258 times:

Quoting eaa3 (Reply 10):
Boeing has probably promised things regarding the B737-900 performance that didn't pan out as expected.

Curious. What things do you think they probably promised?


User currently offlineB777LRF From Luxembourg, joined Nov 2008, 1368 posts, RR: 3
Reply 14, posted (11 months 2 weeks 2 days 5 hours ago) and read 5147 times:

Quoting thenoflyzone (Reply 1):
The B737-9 MAX will require a shorter runway, methinks, what with better engines, and ligher weights.

Not quite correct. The MAX will both be heavier, empty, and have significantly higher maximum design weights than the NG, e.g. MTOW 194.7 vs 187.7 for a MAX9 vs a 900ER. Lift and thrust will, however, remain more or less where they are today. Actually, looks like thrust may be going slightly down (28.0 for a Leap-1B vs 28.4 for a CFM56-7)

Since the -900ER is already a dog when it comes to even slightly challenging conditions, we should expect the -9MAX to be as bad, if not actually worse; the raised nose gear doesn't exactly do wonders for tail clearance on rotation, neither does increased weights without bumping up the thrust.

But all that should not make any material difference to Icelandair; they've also put in an order for 787s for routes the MAX can't cover, either for demand or performance reasons.



From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
User currently offlineroseflyer From United States of America, joined Feb 2004, 9661 posts, RR: 52
Reply 15, posted (11 months 2 weeks 1 day 22 hours ago) and read 5031 times:

Quoting B777LRF (Reply 14):
Since the -900ER is already a dog when it comes to even slightly challenging conditions, we should expect the -9MAX to be as bad, if not actually worse; the raised nose gear doesn't exactly do wonders for tail clearance on rotation, neither does increased weights without bumping up the thrust.

The 900 series certainly is not the right plane for short runways, but a taller nose gear does not influence takeoff performance. Takeoff is about angle of attack, not degrees of rotation, so the ground profile won't make a difference on takeoff. Where it will be a factor is on landing. A higher angle of attack when the nose is on the ground results in lower weight on wheels and less braking effectiveness, but that should be relatively minimal.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineB777LRF From Luxembourg, joined Nov 2008, 1368 posts, RR: 3
Reply 16, posted (11 months 2 weeks 1 day 18 hours ago) and read 4938 times:

Quoting roseflyer (Reply 15):
Takeoff is about angle of attack, not degrees of rotation, so the ground profile won't make a difference on takeoff.

Yes, and no. What the raised gear will mean, is that the pilots will have fewer degrees of rotation available to them. Which means you have to be very, very careful not to over-rotate into a tail-strike. To reduce the chance of that happening, the manual will call for V-speeds a couple of knots higher than they, in lack of a better expresson, 'ought to be', which will have a negative impact on runway performance.



From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
User currently offlineroseflyer From United States of America, joined Feb 2004, 9661 posts, RR: 52
Reply 17, posted (11 months 2 weeks 1 day 13 hours ago) and read 4843 times:

Quoting B777LRF (Reply 16):
Yes, and no. What the raised gear will mean, is that the pilots will have fewer degrees of rotation available to them. Which means you have to be very, very careful not to over-rotate into a tail-strike. To reduce the chance of that happening, the manual will call for V-speeds a couple of knots higher than they, in lack of a better expresson, 'ought to be', which will have a negative impact on runway performance.

I am not sure how the 737-9 will be any different than the 737-900ER. Tail clearance is tight, but I don't think there is any evidence that it is unreasonable. Yes it will take a lot of runway, but the 737-900 series should not have too much trouble operating most of icelandairs routes,

[Edited 2013-10-20 20:04:47]


If you have never designed an airplane part before, let the real designers do the work!
User currently offlinedoug_Or From United States of America, joined Mar 2000, 3414 posts, RR: 3
Reply 18, posted (11 months 2 weeks 1 day 12 hours ago) and read 4820 times:

Quoting B777LRF (Reply 16):
Yes, and no. What the raised gear will mean, is that the pilots will have fewer degrees of rotation available to them.

Did they change the angle of incidence?



When in doubt, one B pump off
User currently onlineplanewasted From Sweden, joined Jan 2008, 528 posts, RR: 0
Reply 19, posted (11 months 2 weeks 1 day 3 hours ago) and read 4735 times:

Quoting roseflyer (Reply 15):
Takeoff is about angle of attack, not degrees of rotation

Won't the drag on the take off roll be higher because of this? That will give slower acceleration and therefore longer runway length requirement. Or maybe it's negligible?


User currently offlineferpe From France, joined Nov 2010, 2804 posts, RR: 59
Reply 20, posted (11 months 2 weeks 22 hours ago) and read 4679 times:

If the thrust of the engines are given by Boeing they should be BET (Boeing Equivalent Thrust) which is defined as the thrust at M 0.25 (which is 163kts at SL on an ISA day) times 1.255. This means a higher bypass engine will have more thrust as the start of the roll and equal at 163kts (which is past V2 for the MAX) for an equal BET.

The MAX has higher weights and therefore more mass to accelerate. Once rotated the dominant drag is induced drag, there the Y winglets help but can not compensate fully for the higher MTOW. I get the following drag values -900ER parasitic 3klbf, induced 14klbf and -9MAX 3klbf parasitic and 15klbf induced. I have deliberately skipped the fractions as the real numbers from my model are close to these numbers and my assumptions around start slats and flaps drag is not of the quality of the rest of the model.



Non French in France
User currently offlineferpe From France, joined Nov 2010, 2804 posts, RR: 59
Reply 21, posted (11 months 2 weeks 18 hours ago) and read 4586 times:

Quoting B777LRF (Reply 16):
What the raised gear will mean, is that the pilots will have fewer degrees of rotation available to them.

It means the pilots will have to rotate less to get the wheels of the ground. Pilots are flying the aircraft based on it's reactions, if a new model requires you to rotate less from a certain nose position to get to your usual references vs. the horizon / the rotate angle on the PFD you learn that immediately. That does not change because your nosegear is longer.


Quoting planewasted (Reply 19):
Won't the drag on the take off roll be higher because of this? That will give slower acceleration and therefore longer runway length requirement. Or maybe it's negligible?

Take a look at the latest 737 MAX airport compatibility brochure:

http://www.boeing.com/boeing/commercial/airports/plan_manuals.page

The airplane seems to sit perfectly level on the ground. If one looks at the difference in height of the entrance door of the -900ER and the MAX we are talking about 0.2m which on 16m length from the MLG means less then a degree angle diff. Should be negligible



Non French in France
User currently offlineB777LRF From Luxembourg, joined Nov 2008, 1368 posts, RR: 3
Reply 22, posted (11 months 2 weeks 17 hours ago) and read 4555 times:

Ferpe,

As always, you submit valuable information of high technical standards, thank you very much for that.

I trust you are also a pilot, or at least knowledgable enough to appreciate some of the challenges pilots face, and thus able to appreciate the issue of having a reduce arc through which you can rotate the aircraft, without suffering a tail-strike. The -900NG is already very susceptible to this condition, and reducing the available arc by even one degree will, I am fairly certain, lead to the manufacturer dictating slightly higher Vr speeds for any given weight on the -9MAX compared to the -900NG. I'm not saying pilots won't get used to it, nor that they will hammer the tail into the ground on a regular basis, but part of the reason for that will be the increased Vr speeds.



From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
User currently offlineferpe From France, joined Nov 2010, 2804 posts, RR: 59
Reply 23, posted (11 months 2 weeks 8 hours ago) and read 4495 times:

Quoting B777LRF (Reply 22):
I trust you are also a pilot,

Yes, military and civilian.

Quoting B777LRF (Reply 22):
I trust you are also a pilot, or at least knowledgable enough to appreciate some of the challenges pilots face, and thus able to appreciate the issue of having a reduce arc through which you can rotate the aircraft, without suffering a tail-strike. The -900NG is already very susceptible to this condition, and reducing the available arc by even one degree will, I am fairly certain, lead to the manufacturer dictating slightly higher Vr speeds for any given weight on the -9MAX compared to the -900NG.

I don't see the logic in this, the V speeds are based on the aerodynamic performance of the airframe, not the pitch margin to tail-strike. The margin between the tail of the aircraft and ground at lift-off will be essentially the same. The tailstrike risk is a function of your rotation speed (the risk of an overswing before the wings lift of the aircraft), you will have to do the rotation a bit less abrupt and more exact to be sure to stop at your predetermined picth angle.

In one ot the fighters I flew we had to aerodynamically brake the aircraft after landing at max pitch with the tail at about 0.2-0.4 m above the runway. Now that is not so diffucult but then you should also pump brake at the same time in order to get the thing stopped before you had no more runway (no continuous braking, it would have killed the brakes and you would have landed in the emergency catch fence at end of runway, no hard pumping and balancing the tail clearance with the stick), after that it was nose down and continued pump braking. It was difficult but one learned how to do it using eyemarks and practice. It is the same for the 737-9 pilots, they learn it. There are more difficult things in flying then doing a sensible rotate.



Non French in France
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17055 posts, RR: 67
Reply 24, posted (11 months 2 weeks 6 hours ago) and read 4478 times:

Quoting ferpe (Reply 23):
In one ot the fighters I flew we had to aerodynamically brake the aircraft after landing at max pitch with the tail at about 0.2-0.4 m above the runway. Now that is not so diffucult but then you should also pump brake at the same time in order to get the thing stopped before you had no more runway (no continuous braking, it would have killed the brakes and you would have landed in the emergency catch fence at end of runway, no hard pumping and balancing the tail clearance with the stick), after that it was nose down and continued pump braking. It was difficult but one learned how to do it using eyemarks and practice. It is the same for the 737-9 pilots, they learn it. There are more difficult things in flying then doing a sensible rotate.

        

It continually surprises me on a.net how many people are extremely worried about tailstrikes and similar things. Yes, they happen, but not very often. As you say, pilots train for the quirks of their airplane until they become background noise. The certification requirements do specify that "unusual skill" should not be required (ok not military...). This is true from the very first light aircraft flown. At a certain point landing the Q400 without hitting the bumbum on the ground isn't a worry anymore, just another constraint.



"There are no stupid questions, but there are a lot of inquisitive idiots."
25 barney captain : Interesting discussion. All I can add is that at similar weights, the -800 has much higher speeds for both take-off and landing as compared to the -70
26 ferpe : That I buy, it makes sense. But the -900ER and the -9 is geometrically the same except one is sitting 0.6° more nose up because the nose landing gea
27 prebennorholm : Nothing to worry about. From the Icelandair site: Icelandair’s current fleet of Boeing 757-200 aircraft configured to hold 183 passengers will remai
28 eaa3 : I'm pretty sure that doesn't make sense. The reason is that Icelandair's hub and spoke system is based upon a 24 hour cycle in which an aircraft will
29 prebennorholm : Icelandair scheduling is a lot more complicated than that, and it is very seasonal. In summer one plane makes not two, but three roundtrips a day to
30 Natflyer : Advertised range from OEMs says very little for actual operations. B737 MAX 9 can take 2 AUX tanks, but they are useless in airline operations, as po
31 onebadlt123 : The 739 does not have any performance issues related to BOS specifically. We run them on BOS-SFO/LAX regularly without structural issues. In the wint
32 Max Q : Very interesting. Reality is the 757 really is unique and nothing built or in development can replace it.
33 Post contains images Starlionblue : It's a weird market quirk actually. This aircraft has very desirable characteristics, as evidenced by its strong sales and continued use, but seeming
34 Max Q : I wish Sblue but there's just no suitable engine anywhere close to it's thrust class. But Boeing could have addressed the issue The 757 occupies such
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