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kknudson 08-06-2009 10:33 PM

Question for the Pilots here
 
There is the Southwest commercial where they state that their 737s fly at an average speed of 590 mph.
Yet the brochure I just got from a SW flight shows the 737 speed as 544 mph.

So for fun I set them an email questioning that, fun not serious, and got the response that , every claim in this spot has been approved through all proper channels.

So 590 mph seems a bit fast.

Just curious.

KarTek 08-06-2009 10:44 PM

Boeing's specs for the 737 family quote mach .785 or .78 @ 35,000 depending on the model which converts to around 593+ MPH.

Edit:

The calculator I used didn't account for altitude so the 593 MPH would be at sea level.

Brian Carlton 08-06-2009 11:00 PM

Quote:

Originally Posted by kknudson (Post 2264304)
There is the Southwest commercial where they state that their 737s fly at an average speed of 590 mph.

EDITED:

The commercial is untruthful. There is no possibility of the 737 averaging 590 mph without a tailwind.

WVOtoGO 08-06-2009 11:03 PM

Cruise speed?
Max speed?
Airspeed?
Ground speed?
What speed, I need?

Most of the newer 737-700s have a max speed of 470ish kts. That’s about 540ish mph.
That’s the max speed the aircraft can fly (certified) through the air.
Their cruise speed is something like 450ish kts. That’s about 515-520ish mph.
That’s all standard day figures for the aircraft itself. No winds. Straight and level.

Now if they go up and catch a 100+ mph tail wind. Their cruising speed over the ground can easily break 590 mph. That number is not too fast.

The brochure is probably giving you the aircrafts max speed.
The commercial is probably giving you their average ground speed.
(At altitude)

Both are accurate numbers. Just a bit confusing when they don’t tell you exactly what speed they are talking about.

Brian Carlton 08-06-2009 11:13 PM

Quote:

Originally Posted by WVOtoGO (Post 2264335)
Most of the newer 737-700s have a max speed of 470ish kts. That’s about 540ish mph.

The specs call a cruising speed of .785 Mach. However they also call a cruising speed of only 514 mph. With the speed of sound at 768 mph...........I'm missing something here...........:confused:

EDIT: I figured it out.........the speed of sound at 35,000 feet is approx. 690 mph. .785 Mach gives a speed of 541 mph.

So, clearly SWA is untruthful. The aircraft cannot average 590 mph under any circumstances without a tailwind.

kknudson 08-06-2009 11:22 PM

Well thanks guys.

So I guess the definition is air speed or ground speed.

It was just a curiosity.

Thanks

WVOtoGO 08-06-2009 11:27 PM

Like missing that the .785 is calculated from CAS and TAS at a specific altitude.
And the 768 is in 68 deg. air.

WVOtoGO 08-06-2009 11:28 PM

Oops...
I see you got it.
Good job.
Never mind.
:D

WVOtoGO 08-06-2009 11:31 PM

Quote:

Originally Posted by kknudson (Post 2264351)
Well thanks guys.

So I guess the definition is air speed or ground speed.

It was just a curiosity.

Thanks

You're quite welcome.

BTW -
When you hook up with the aviation nuts on this forum...
NOTHING is handled as “just a curiosity.”
:D

Brian Carlton 08-06-2009 11:34 PM

Quote:

Originally Posted by WVOtoGO (Post 2264356)
Oops...
I see you got it.
Good job.
Never mind.
:D

Thanks..........yep, the figures were too disparate to ignore..........

WVOtoGO 08-06-2009 11:41 PM

Quote:

Originally Posted by Brian Carlton (Post 2264341)
The specs call a cruising speed of .785 Mach. However they also call a cruising speed of only 514 mph. With the speed of sound at 768 mph...........I'm missing something here...........:confused:

EDIT: I figured it out.........the speed of sound at 35,000 feet is approx. 690 mph. .785 Mach gives a speed of 541 mph.

So, clearly SWA is untruthful. The aircraft cannot average 590 mph under any circumstances without a tailwind.

Why would you say that?
Most of their flights could have one hell of a tail wind.
They will fight for the best winds, tail or head.
Their average speed at altitude could easily average 590.
(Especially for the certain flights they used to make the commercial data from.)

A bit misleading, perhaps. But not clearly untruthful. ;)


Also - Don’t ever mix the aircrafts certified standard operating specs with its actual flight data. They seldom, if ever, jive.

Brian Carlton 08-06-2009 11:47 PM

Quote:

Originally Posted by WVOtoGO (Post 2264364)
Why would you say that?
Most of their flights could have one hell of a tail wind.
They will fight for the best winds, tail or head.
Their average speed at altitude could easily average 590.


I'm not believing that they can makeup 50 mph.........on average...........for the entire fleet...........with tailwinds.

They fly all routes in both directions several times in a given day. This tends to minimize any benefits from the wind.

The statement is untruthful.

WVOtoGO 08-06-2009 11:58 PM

You are correct in your thinking.
However...We're talking advertising here.

So once again I’ll post:
(Especially for the certain flights they used to make the commercial data from.)

They didn't have to tell you that the 590 is average for their LA to NY flights only.

If I told you that I flew faster than the speed of sound on a trip the other day, would that be a lie? Think about it. ;)

No reason the ad can't have a little note in very small print that says something to the effect of: Based on east bound routes longer than 750 miles. :D

Brian Carlton 08-07-2009 12:02 AM

Quote:

Originally Posted by WVOtoGO (Post 2264376)
You are correct in your thinking.
However...We're talking advertising here.

So once again I’ll post:
(Especially for the certain flights they used to make the commercial data from.)

They didn't have to tell you that the 590 is average for their LA to NY flights only.

If I told you that I flew faster than the speed of sound on a trip the other day, would that be a lie? Think about it. ;)

No reason the ad can't have a little note in very small print that says something to the effect of: Based on east bound routes longer than 750 miles. :D

Of course..........if you qualify the statement...........anything can become the truth.

I take it at face value...........fleet average.

On that basis, it's untruthful.

I took a DC-10 from LA to NY. Total time wheels up to wheels down was 4:10. 2451 miles at an average speed of 589 mph. I still can't believe it and I was on it.:eek:

WVOtoGO 08-07-2009 12:18 AM

I hear ya.
But we’re talking advertising here.

You can question it. And they can come right back with: "That’s the fleet average for east bound flights with cruise power set descents from cruise altitude to the first 5K feet lost mark."

And then all you can say is: "Huh?:confused:"

:D

LaughingGravy 08-07-2009 11:38 AM

The plane could go at 600, you'd still be at the mercy of delays at the airports in both takeoff and landing as well as gate issues.

On the ground...Me next to a Z06. He planks it. I accelerate normally and pull up to him at the next light.

Brian Carlton 08-07-2009 11:45 AM

Quote:

Originally Posted by LaughingGravy (Post 2264634)

On the ground...Me next to a Z06. He planks it. I accelerate normally and pull up to him at the next light.

He's faster than you............the time at the stoplights doesn't count in the overall trip time. I've come to this conclusion after many years of observation of thousands of drivers. It must be true.

Mistress 08-07-2009 12:41 PM

Quote:

Originally Posted by WVOtoGO (Post 2264335)
Cruise speed?
Max speed?
Airspeed?
Ground speed?
What speed, I need?

Most of the newer 737-700s have a max speed of 470ish kts. That’s about 540ish mph.
That’s the max speed the aircraft can fly (certified) through the air.
Their cruise speed is something like 450ish kts. That’s about 515-520ish mph.
That’s all standard day figures for the aircraft itself. No winds. Straight and level.

Now if they go up and catch a 100+ mph tail wind. Their cruising speed over the ground can easily break 590 mph. That number is not too fast.

The brochure is probably giving you the aircrafts max speed.
The commercial is probably giving you their average ground speed.
(At altitude)

Both are accurate numbers. Just a bit confusing when they don’t tell you exactly what speed they are talking about.

If you can fly faster and jump higher in your PF Flyers Your bound to sell more tickets....

BamaMB 08-07-2009 08:16 PM

The way Southwest pilots fly, I think they are talking about an average speed of 590 MPH crossing the fence on approach to landing. :D

http://thm-a03.yimg.com/image/131faa11e9c82918


http://thm-a01.yimg.com/image/0ba76ae64c82cb24

Skippy 08-08-2009 05:58 AM

Um, well I managed to average 53 mph ground speed in a 240D going from Coronado to Carson City.


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