AmericanF100
Topic Author
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Joined: Mon Aug 20, 2001 1:24 am

How Fast Do Planes Fly?

Tue Jan 08, 2002 11:53 am

I was playing FS2002 and I was questioning my speed. First, do planes follow mach or knots when flying??? If knots, how many knots when at cruising speed??? If mach, what mach when cruising???

Thanks, Matt~
 
McRingRing
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Joined: Mon Dec 10, 2001 2:59 am

RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 12:10 pm

You can find info on the cruising speeds here:

http://www.airliners.net/info/
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CPDC10-30
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RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 12:53 pm

At cruising altitudes, speed is set by Mach number, on takeoff, climb, landing and approach knots are used. A certain mach number for the same number of KIAS will increase with altitude. For example, 240 knots is a higher mach number at 31,000 ft than at 2,000 ft.

The 747 has the fastest normal cruise speed of commercial airliners (excluding the Concocrde of course) with a long-range speed of M. 0.85. Other aircraft typically fly slower such as the A340 (0.82) and the 767 (0.80).
 
IMissPiedmont
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RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 12:53 pm

Knots below 18000 ft, mach above.
The day you stop learning is the day you should die.
 
A330300
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RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 1:28 pm

Also- The barometric pressure is set to a standard 29.92 aboe FL180.
 
cv640
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RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 2:20 pm

On The CRJ we fly 200 KIAS from acceleration altitude to 3000 feet, 250 after that till 10000 and then 290 after that. We fly 290 unbtil we reach .74 Mach and then matain that.
 
POSITIVE RATE
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RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 2:36 pm

"knots below 18,000ft mach above"

Not necesarily I miss piedmont. It depends upon the changeover level of the particular aircraft on the day i.e the 727 changeover level is normally around the FL270 mark and the F-28 changeover level around the FL230 mark- it varies.
 
NZ767
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RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 3:18 pm

Ahh Positive rate, I think you're confused there.
We're talking Transition levels and they don't vary from aircraft to aircraft at all; sheesh, imagine the accident rate if that were the case.

They vary from country to country, eg 18000 feet in the US, 6000 feet in the UK, 11000 feet here in New Zealand and so on.

AmericanF100, to answer you question, generally "Knots" are used below transition level and "Mach" (a percentage of the speed of sound) is used above transition level.
Also, altitude readings above transition are known as "Flight Levels".

An aircraft climbing through transition level will have to reset it's barometric pressure to the standard setting of 1013.2 millibars (29.92 inches of Mercury).

Mike  Smile
 
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derekf
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RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 8:21 pm

As far as I'm aware Positive Rate is right. You do not change to flying Mach at the transition altitude. If that were the case in the UK aircraft would changeover to flying Mach at 5000ft. That is not the case. On the Avro RJ you generally climb at 250 or 280 kts until you reach 0.66M which is say 24000ft.

Derek F
Whatever.......
 
NZ767
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RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 8:28 pm

Oh, got your point there about changeover to Mach DerekF.
But I took his post to mean "different transition levels for different aircraft" which obviously would create chaos.

Mike  Smile
 
POSITIVE RATE
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RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 9:28 pm

No i didn't mean different transition levels for different aircraft but i meant different changeover levels for different aircraft which is as DerekF described above. Changeover level is the altitude at which the climb IAS is equal to the corresponding climb mach no. e.g the B 727 climbs at 310 KIAS/ 0.78M
 
Cathay Pacific
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RE: How Fast Do Planes Fly?

Tue Jan 08, 2002 9:38 pm

Does the ground speed shown on Airshow mean anything? Is it really the speed that the plane is going?

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NZ767
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RE: How Fast Do Planes Fly?

Wed Jan 09, 2002 5:26 am

Yeah I got ya now Positive rate.
Sorry!!  Smile
 
Guest

RE: How Fast Do Planes Fly?

Wed Jan 09, 2002 5:28 am

Planes fly at about 12,000 Knots an hour. It's true. Smile/happy/getting dizzy
 
jhooper
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RE: How Fast Do Planes Fly?

Wed Jan 09, 2002 7:12 am

"Planes fly at about 12,000 Knots an hour."

Just trying to do the math here. What you're saying is that a plane flies 12,000 nautical miles per hour per hour. That would suggest a unit of acceleration, which doesn't suggest anything about cruising speed, right?
Last year 1,944 New Yorkers saw something and said something.
 
Tom_EDDF
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RE: How Fast Do Planes Fly?

Wed Jan 09, 2002 8:48 am

Cathay Pacific,

I'm not sure where the Airshow Numbers come from, but the GS shown should be very close to the real speed of the aircraft above ground. This should include the wind factors (head/tail/crosswinds, also shown in airshow).

The speed indicated on the cockpit instruments (even in MS FS) is ususally the mach number and the indicated airspeed (IAS) in knots. IAS varies with the flying altitude, i.e. 250kts IAS at 2000ft could mean around 250kts ground speed. At FL410 (41000ft) and with tailwind, 250kts IAS could also mean 550kts GS, because of the wind and the thinner air.

The mach number also does not compensate the wind components, i.e. flying an Airbus A340 at m.82 could either mean cruising above the ground at 480 knots (with little winds) or going much faster, say 550knots (with around 80kts of tailwind or so).

The mach number therefore indicates the TAS, the True Air Speed, which is constant at any altitude. It is the actual airspeed of the aircraft through the air mass. As an aircraft climbs, the indicated airspeed (IAS) will decrease as the air becomes thinner and the impact pressure is reduced, while the TAS remains stable. For a given TAS, indicated airspeed will decrease with altitude.

Sounds complicated? It sure is. Maybe I'm wrong with all this, but I'm sure someone could clarify...

Cheers,
Tom.

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