Iloveboeing
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Can The 777 Cruise At Mach 0.85?

Tue Feb 26, 2008 1:10 am

I was wondering if the 777 can cruise at Mach 0.85, like the 747 and 787? Boeing lists the typical cruise at Mach 0.84 on their website, but, in the past, I've heard them claim that the 787 will cruise at Mach 0.85, similar to the cruising speed of the 747 and 777, so I was wondering if normal cruise for the 777 could be Mach 0.85. Thanks!
 
Mir
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RE: Can The 777 Cruise At Mach 0.85?

Tue Feb 26, 2008 2:55 am

It could certainly cruise at .85, but you'd be losing a lot more in efficiency than you'd be gaining in speed.

Quoting Iloveboeing (Thread starter):
in the past, I've heard them claim that the 787 will cruise at Mach 0.85, similar to the cruising speed of the 747 and 777

The 777's normal cruise is .84. The difference between .84 and .85 is only about 10kts on average, so it is fair to say that the 787 has a similar cruising speed to the 777 (though it is a bit faster).

-Mir
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zeke
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RE: Can The 777 Cruise At Mach 0.85?

Tue Feb 26, 2008 7:05 am



Quoting Iloveboeing (Thread starter):
Boeing lists the typical cruise at Mach 0.84 on their website, but, in the past, I've heard them claim that the 787 will cruise at Mach 0.85, similar to the cruising speed of the 747 and 777, so I was wondering if normal cruise for the 777 could be Mach 0.85. Thanks!

The 777 can cruise at the same speed as the 744, but it would be using more fuel than normal if they both departed the same point along the same route.

In our airline we do not use a constant mach number for cruise, it varies with the cost index selected in the FMC, altitude, and weight. The 744 for example will cruise anywhere from 0.83 to 0.85 FL330-FL360.
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mandala499
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RE: Can The 777 Cruise At Mach 0.85?

Tue Feb 26, 2008 8:12 pm



Quoting Iloveboeing (Thread starter):
so I was wondering if normal cruise for the 777 could be Mach 0.85.

I got a friend who is dyslexic whenever he sees the CI input on the FMC... 150 instead of 051... He also goes 0.85 often...  Smile The funny thing is, he burns less fuel... *bangs head on table* The last part of my comment can be taken as a wind up...
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Zkpilot
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RE: Can The 777 Cruise At Mach 0.85?

Thu Feb 28, 2008 1:51 pm



Quoting Zeke (Reply 2):
n our airline we do not use a constant mach number for cruise, it varies with the cost index selected in the FMC, altitude, and weight. The 744 for example will cruise anywhere from 0.83 to 0.85 FL330-FL360.

Most airlines operate in this manner... more cost effective.
Just been on a flight with a decent tailwind... 1100km/h g/s (584kt and about 0.92mach approx g/s lol) in a 763. Normal 3 hour trip was done in 2 hours Big grin
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CX Flyboy
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RE: Can The 777 Cruise At Mach 0.85?

Sat Mar 01, 2008 2:53 pm

I've done Mach 0.88 before, diverting in a medical emergency.
 
RJdxer
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RE: Can The 777 Cruise At Mach 0.85?

Mon Mar 03, 2008 12:28 am



Quoting Zkpilot (Reply 4):
Most airlines operate in this manner... more cost effective.

But a factor is also time. If cruising at .85 will make up enough minutes without dramatically upping the burn, you would be expected to get the flight there on time. There are several ways to accomplish this besides crz at .85
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KELPkid
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RE: Can The 777 Cruise At Mach 0.85?

Mon Mar 03, 2008 5:20 am



Quoting CX flyboy (Reply 5):
I've done Mach 0.88 before, diverting in a medical emergency.

Is that close to the Mmo speed?
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tito
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RE: Can The 777 Cruise At Mach 0.85?

Fri Mar 07, 2008 8:05 am



Quoting Zeke (Reply 2):
In our airline we do not use a constant mach number for cruise, it varies with the cost index selected in the FMC, altitude, and weight. The 744 for example will cruise anywhere from 0.83 to 0.85 FL330-FL360

...and don't forget wind too. FMC will increase cruise mach number with a headwind.
 
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zeke
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RE: Can The 777 Cruise At Mach 0.85?

Fri Mar 07, 2008 10:14 am



Quoting Tito (Reply 8):
..and don't forget wind too. FMC will increase cruise mach number with a headwind.

And decrease with a tailwind.....
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
kimberlyRJ
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RE: Can The 777 Cruise At Mach 0.85?

Fri Mar 07, 2008 11:06 am

Hello

I work on both the Boeing 747 & Boeing 777 and the B744 always flies faster then the B772 as far as I have seen. Sometimes when returning from North American to the UK when we have a nice tail wind we sometimes get to M.85 but it’s not as often as the B744.

Regards

Kimberly
 
CX Flyboy
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RE: Can The 777 Cruise At Mach 0.85?

Sun Mar 09, 2008 10:36 am



Quoting KELPkid (Reply 7):
Is that close to the Mmo speed?

Mach 0.89 is the MMO, so yes it was close. Ok in smooth air but you wouldn't want to cruise at that in turbulence.

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