Supersonic in a 777

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Feb 8, 2007 | 5:27 pm

#31

indufan

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Quote:

Originally Posted by carpboy

Some allow GPS units, DL or CO, I can't remember exactly, plainly listed in the inflight mag.

Quote:

Originally Posted by M2swim

pull out your handheld Garmin, illegally turn it on while in the plane, and record the 800+ GS on it. That would really impress your friends!

I use my GPS routinely on Delta flights. It is neither included or excluded in the magazine. No FA has ever even mentioned it and I have had it is clear plain view a lot. My top speed: 730 mph. I have it in my pocket tonight if I ever get around to flying.

Feb 8, 2007 | 11:10 pm

#32

OttoMH

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On the way back from JFK to LHR in December on a BA747 we were riding the Jetstream at 690-700mph ground-speed. Only 70mph short

Feb 8, 2007 | 11:48 pm

#33

nnn

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Never mind.

Last edited by nnn; Feb 10, 2007 at 2:11 am Reason: I stand corrected.

Feb 9, 2007 | 9:27 am

#34

LarryJ

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Quote:

Originally Posted by carpboy

And they don't call them FL's, just 'F', as in F80.

Who does?

In aviation, it certainly is FL180, FL330, etc. In 26 years as a pilot I've never seen an altitude written as F80.

Feb 9, 2007 | 9:32 am

#35

LarryJ

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Quote:

Originally Posted by nnn

Actually, FL33 can theoretically exist in the U.S. It would just require a very, very, very high altimeter setting on the ground.

I don't understand you point. FL33 would never be an assignable altitude in US airspace. It indicates 3,300' above the standard pressure datum of 29.92" but the US transition level is always FL180 so no FL below FL180 will ever be assigned.

Sometimes the lower flight levels can become unusable due to low pressure. For example, if the local altimeter setting drops below 29.92 then FL180 becomes unusable as you'd no longer have 1000' separate between FL180 and 17,000' (or 500' separation between FL180 and 17,500' the highest VFR altitude). At 28.92 FL190 would become unusable, etc.

Feb 9, 2007 | 5:22 pm

#36

nnn

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Never mind...

Last edited by nnn; Feb 10, 2007 at 2:12 am Reason: I stand corrected.

Feb 9, 2007 | 10:29 pm

#37

LarryJ

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Quote:

Originally Posted by nnn

Thus, FL170, FL160, etc., are assignable altitudes in the United States.

They are not. FL180 is the lowest flight level that can be assigned in the US. If FL180 is below 18,000' MSL due to low pressure then FL180 is not assignable.

Feb 10, 2007 | 2:13 am

#38

nnn

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Quote:

Originally Posted by LarryJ

They are not. FL180 is the lowest flight level that can be assigned in the US. If FL180 is below 18,000' MSL due to low pressure then FL180 is not assignable.

Thanks, you're right. I should have done my research before speaking.

Feb 10, 2007 | 2:22 am

#39

chornedsnorkack

Join Date: Dec 2006

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Quote:

Originally Posted by LarryJ

They are not. FL180 is the lowest flight level that can be assigned in the US. If FL180 is below 18,000' MSL due to low pressure then FL180 is not assignable.

And what happens if, due to high pressure, FL180 is above 18 000 feet?

Feb 11, 2007 | 3:07 pm

#40

mbreuer

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Quote:

Originally Posted by chornedsnorkack

And what happens if, due to high pressure, FL180 is above 18 000 feet?

That's OK - you still have proper separation from aircraft below 18000MSL.

Feb 11, 2007 | 9:09 pm

#41

LarryJ

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Quote:

Originally Posted by chornedsnorkack

And what happens if, due to high pressure, FL180 is above 18 000 feet?

Then the distance between an airplane assigned 17,000' and one passing directly overhead at FL180 is more than 1000'.

Feb 11, 2007 | 10:22 pm

#42

Fermat

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doesn't such a strong tailwind increase the risk of mach buffet?

Feb 12, 2007 | 12:43 pm

#43

LarryJ

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Quote:

Originally Posted by Fermat

doesn't such a strong tailwind increase the risk of mach buffet?

Tailwinds are irrelevant to mach speed and mach buffet.

Mach buffet occurs when the air flowing over the top of the wing approaches mach 1.0. Airflow over the wing is unaffected by wind (unless there is wind shear).

Apr 7, 2019 | 7:31 pm

#44

StormchaserNYC

Join Date: Apr 2019

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Actually back on June 1st, 2010. I was on my way back from Japan on JAL flight 007 on their 777-300 ER and the jet had a top speed of 820 MPH. I was shocked when I saw that speed on the seat mounted TV I expected the Captain to make an announcement, however he never did, and I could tell we were in the jet stream due to layered clouds well below the plane at the extremely fast rate of speed for that brief moment of time. Most of the time of the flight was the speed was <700 MPH.