futureatp
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3 Queries From A Recent WN Trip I Took.

Thu Apr 26, 2007 8:38 am

First I apologize if any of the questions I have already have been discussed at an previous date. I'm not the best at doing those kind of searches.

2nd, I enjoy reading everyone's responses on this site and forum. But this is really intended for those familiar with 737(and similar sized aircraft) operating data and those familiar with Southwest Airlines ops too.

I recently flew a southwest flight from PHX to MCI last sunday. Aircraft was a -700(the 2000thNG special edition as a matter of fact!). Return though OKC last night, both ac -300s. Anyway, from a curious passenger point of view I noticed a few things that made me curious.

1. If initial alt. clearance is past 10,000ft, what would be good general #'s for airspeed, rate of climb, and pitch angle on a -700 and how would it compare to the -300?
When we departed PHX, the 10,000ft cabin announcement came before we turned east after departing runway 25R. Climbout was steep though 10,000ft. On the OKC-PHK flight, it took a noticeable amount longer when the 10,000ft announcement was made. I didnt get a good feel for the climbout on the MCI-OKC leg due to thunderstorms.

2. What is the VLE-VLO speeds on the 737 family?
When approaching MCI last sunday night, we landed on runway 19R. While still southwest MCI, the gear was extended while the speed brakes were still deployed. No Flaps until turning base-final. The speed brakes had been deployed for a while, but at what I would call a shallow angle. I'm guessing the gear was extended that early to aid in the slowdown of the aircraft which is why i'm curious on the speed limitations on the gear.

3. Due to Southwest's open seating policy, is any kind of figure that has to be taken into account when loading the aircraft cargo holds for weight and balance?
On the PHX-MCI leg and OKC-PHX leg I had an entire row to myself while all most all of the seats in front of the over-wing emergency rows were full. When given the choice, ppl seem to take an middle seat on WN just to be near the front to save a few minuets when deplaning. Which is good for me because I like having 3 seats to myself!

Thanks in advance.
John
 
EMBQA
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RE: 3 Queries From A Recent WN Trip I Took.

Fri Apr 27, 2007 7:26 pm

Quoting FutureATP (Thread starter):
1. If initial alt. clearance is past 10,000ft, what would be good general #'s for airspeed, rate of climb, and pitch angle on a -700 and how would it compare to the -300?

How much fuel, what are the weather conditions, where is the wind from, what is the air temp, how much do we weigh, are there noise restrictions, are there traffic issues in the area...?? Too many variables to answer that question

Quoting FutureATP (Thread starter):
2. What is the VLE-VLO speeds on the 737 family?

See above.....

Quoting FutureATP (Thread starter):
3. Due to Southwest's open seating policy, is any kind of figure that has to be taken into account when loading the aircraft cargo holds for weight and balance?

Not really. Commercial aircraft are not susceptible to the w&b requirements of say a C152
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Tristarsteve
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RE: 3 Queries From A Recent WN Trip I Took.

Fri Apr 27, 2007 11:14 pm

Quoting EMBQA (Reply 1):
Not really. Commercial aircraft are not susceptible to the w&b requirements of say a C152

Some are. Tell that to a loadmaster on a MD80 or a F100. I have seen a few extra passengers move the balance so that all the bags that were planned in the fwd hold have to be moved to the rear hold.

We fly B767-300 with loads of freight, around 10tons in the fwd hold. The dispatcher must be careful to seat the pax further back by blocking out seats at the front of the cabin so the aircraft does not go nose heavy.
 
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Jetlagged
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RE: 3 Queries From A Recent WN Trip I Took.

Fri Apr 27, 2007 11:25 pm

The 737 gear can be extended up to 270 knots/Mach 0.82. Unaffected by aircraft weight, etc.

737 speedbrakes are notoriously ineffective. Mostly they just create buffet. Extending the gear is much more effective in slowing a 737 down if rapid deceleration is necessary.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
PGNCS
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RE: 3 Queries From A Recent WN Trip I Took.

Sat Apr 28, 2007 2:39 am

Quoting Jetlagged (Reply 3):
The 737 gear can be extended up to 270 knots/Mach 0.82. Unaffected by aircraft weight, etc.

737 speedbrakes are notoriously ineffective. Mostly they just create buffet. Extending the gear is much more effective in slowing a 737 down if rapid deceleration is necessary.

Very true. The 737 is notoriously difficult to get down in a pinch, and the speed brakes are sub-par; the gear is sometimes the best option available for drag. Flap speeds are relatively slow on the 737, so I'm not surprised you saw them after the gear was down.

Quoting TristarSteve (Reply 2):
Not really. Commercial aircraft are not susceptible to the w&b requirements of say a C152

Some are. Tell that to a loadmaster on a MD80 or a F100. I have seen a few extra passengers move the balance so that all the bags that were planned in the fwd hold have to be moved to the rear hold.

We fly B767-300 with loads of freight, around 10tons in the fwd hold. The dispatcher must be careful to seat the pax further back by blocking out seats at the front of the cabin so the aircraft does not go nose heavy.

Also true. Most commercial aircraft are very forgiving for weight and balance, but good load planning is critical, especially in some models.
 
futureatp
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RE: 3 Queries From A Recent WN Trip I Took.

Sat Apr 28, 2007 4:09 am

Wow, 270kts for the gear. I had no idea it was that high. For some reason I had 220kts in my head. One could really feel the aircraft slow down after they were extended. I understand the concept of using the gear as brakes as I was trained to do the same in the Beech Bonanza (apples to oranges eh?!!). And it makes sense to me now why I thought we were still traveling at around 250kts (once again, passenger estimation!) and yet the speed brakes were deployed albeit at a shallow angle.

Anyway, on the climbout out of PHX, it seemed like we reached 10,000ft in less than 4 min. People are always bragging on the 757, but to me that was the most impressive climb out I have ever been on. I was just looking for basic numbers for performance. Nothing exact.

Thanks guys

John
 
LASoctoberB6
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RE: 3 Queries From A Recent WN Trip I Took.

Sat Apr 28, 2007 8:02 am

Quoting PGNCS (Reply 4):
Flap speeds are relatively slow on the 737

why did Boeing make those so slow deploying?
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PGNCS
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RE: 3 Queries From A Recent WN Trip I Took.

Sat Apr 28, 2007 8:50 am

Quoting LASOctoberB6 (Reply 6):
Flap speeds are relatively slow on the 737

why did Boeing make those so slow deploying?

Sorry if I wasn't clear. They aren't slow to extend, the aircraft has to be relatively slow (compared to some other aircraft) to extend them. The slower you are when you have flaps extended, the less stress the components are under. The less stress you put them under, the longer they last or the lighter and less substantial you can make them. I am not remotely speaking as to how Boeing came up with the maximum flap extension speeds for the 737, but every design is a compromise. The initial 737 wing design provides for good low-speed maneuvering when clean, so I would hazard to presume that they elected to exploit that with lighter flaps. Perhaps someone else with a better knowledge of the 737 wing design process could shed more light on it.
 
Slovacek747
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RE: 3 Queries From A Recent WN Trip I Took.

Sat Apr 28, 2007 10:30 am

We are leaving out a crucial point. The elevation at PHX is much higher than MCI... which means you would reach 10,000 quicker. Throw in the rest of the variable and its possible to hop right on up to FL 100.

Slovacek747
 
PGNCS
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RE: 3 Queries From A Recent WN Trip I Took.

Sat Apr 28, 2007 10:54 am

Quoting Slovacek747 (Reply 8):
We are leaving out a crucial point. The elevation at PHX is much higher than MCI... which means you would reach 10,000 quicker. Throw in the rest of the variable and its possible to hop right on up to FL 100.

Slovacek747

Well, KMCI is at 1026' and KPHX is at 1135'. 109 feet is not really that consequential unless you're using a stopwatch.
 
ytib
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RE: 3 Queries From A Recent WN Trip I Took.

Sat Apr 28, 2007 10:55 am

Quoting Slovacek747 (Reply 8):
We are leaving out a crucial point. The elevation at PHX is much higher than MCI... which means you would reach 10,000 quicker. Throw in the rest of the variable and its possible to hop right on up to FL 100.

KPHX - 1135ft
KMCI - 1026ft

However:
KTUS - 2643ft
 
LASoctoberB6
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RE: 3 Queries From A Recent WN Trip I Took.

Sat Apr 28, 2007 11:46 am

Quoting PGNCS (Reply 7):
Sorry if I wasn't clear. They aren't slow to extend, the aircraft has to be relatively slow (compared to some other aircraft) to extend them. The slower you are when you have flaps extended, the less stress the components are under. The less stress you put them under, the longer they last or the lighter and less substantial you can make them. I am not remotely speaking as to how Boeing came up with the maximum flap extension speeds for the 737, but every design is a compromise. The initial 737 wing design provides for good low-speed maneuvering when clean, so I would hazard to presume that they elected to exploit that with lighter flaps. Perhaps someone else with a better knowledge of the 737 wing design process could shed more light on it.

thanks much for clearing that up!
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rsbj
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RE: 3 Queries From A Recent WN Trip I Took.

Sat Apr 28, 2007 5:25 pm

1. After passing 10,000' I have found the 700 climbs at 3800-4000 fpm and at 285-290 KIAS (tailwind Eastbound lowers climb speed, might be 310 Westbound) at weights typical of your short leg with say 100 pax. A -300 would be in the range of 2500-3000 fpm and add 10 KIAS to the above speeds. Though the NG's and Classics have similar power-to-weight ratios, the 700's fan is more modern and doesn't suffer from "fan decay" as bad. If you give me how many pax you had on board, I can look up the rate-of-climb in my manual and it will be very close barring it wasn't extremely hot that day.

2. You can extend the gear at 270 KIAS, and once down, you can excellerate to 320. To retract the gear, the max speed is 235 KIAS. The speedbrakes on the 737's are not too effective, they work, but they add more noise and bumps than I consider worth it. If I do use speedbrakes, I use them as your pilots did, and that is to say just a little. When they approach full up, the turbulent air hits the tail making all that fuss. At Southwest we are very carefull not to slow down by using flap drag. Just the opposite, to preserve the planes we are going to use for 25 years we deploy the flaps to the next lower setting at the current flap settings minimum speed.

3. I asked this very question, and it is figured out by years and years of data on where people sit when the airplane has various pax loads. The 737's CG envelope for takeoff is very generous, so that helps a lot too. Also, the cargo is weighed and loaded precisely, so that portion of the payload is a known entity.

Turned out to be a long-winded post, apoligies.

Rick
I fly really fast and take a lot of chances.
 
N353SK
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RE: 3 Queries From A Recent WN Trip I Took.

Sat Apr 28, 2007 11:30 pm

Quoting EMBQA (Reply 1):
Not really. Commercial aircraft are not susceptible to the w&b requirements of say a C152

You've apparently never done COG calculations on an RJ or small Prop I would assume...
 
Slovacek747
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RE: 3 Queries From A Recent WN Trip I Took.

Sun Apr 29, 2007 7:02 am

I apologize for my comment. I woulda assumed PHX was a lot higher than MCI. Thanks for the correction.

Slovacek747
 
S12PPL
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RE: 3 Queries From A Recent WN Trip I Took.

Tue May 15, 2007 5:50 am

Quoting N353SK (Reply 13):
You've apparently never done COG calculations on an RJ or small Prop I would assume...

And neither have you...

It's statements like these:

Quoting EMBQA (Reply 1):
Not really. Commercial aircraft are not susceptible to the w&b requirements of say a C152

That show how very little you know about what you speak of on this site.
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KELPkid
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RE: 3 Queries From A Recent WN Trip I Took.

Tue May 15, 2007 8:04 am

Quoting FutureATP (Reply 5):
Wow, 270kts for the gear. I had no idea it was that high. For some reason I had 220kts in my head. One could really feel the aircraft slow down after they were extended.

I don't know about the 737, but in many types, you won't be the maintenance folks' favorite person if it's found out that you regularly extend the gear at the VLE  Wink
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2H4
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RE: 3 Queries From A Recent WN Trip I Took.

Tue May 15, 2007 8:17 am




Quoting EMBQA (Reply 1):
Not really. Commercial aircraft are not susceptible to the w&b requirements of say a C152

Obviously weight is a factor in the 152, but thinking back to my experience flying them, I wonder....is it even possible to get the thing out of balance?

I think you'd have to be a real knucklehead, and haul around blocks of granite in the back...  Wink


2H4


Intentionally Left Blank
 
charlienorth
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RE: 3 Queries From A Recent WN Trip I Took.

Tue May 15, 2007 8:31 am

Quoting 2H4 (Reply 17):
Obviously weight is a factor in the 152, but thinking back to my experience flying them, I wonder....is it even possible to get the thing out of balance?

I think you'd have to be a real knucklehead, and haul around blocks of granite in the back...

When I went for my PPL years ago,Iused to wonder about this on every take-off,neither my instructor or myself were "little guys"

On the other hand a C177 Cardinal I understand is a realy finicky w&b princess,I know a guy who parted out a couple insurance wrecks,and they all got that way from attempting a take-off without proper loading.
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