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How Fast Do Planes Fly?  
User currently offlineAmericanF100 From United States of America, joined Aug 2001, 244 posts, RR: 0
Posted (12 years 11 months 3 weeks 5 days 21 hours ago) and read 20886 times:

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~

15 replies: All unread, jump to last
 
User currently offlineMcringring From , joined Dec 1969, posts, RR:
Reply 1, posted (12 years 11 months 3 weeks 5 days 21 hours ago) and read 20823 times:

You can find info on the cruising speeds here:

http://www.airliners.net/info/


User currently offlineCPDC10-30 From United Kingdom, joined Feb 2000, 4811 posts, RR: 23
Reply 2, posted (12 years 11 months 3 weeks 5 days 20 hours ago) and read 20803 times:

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).


User currently offlineIMissPiedmont From United States of America, joined May 2001, 6346 posts, RR: 33
Reply 3, posted (12 years 11 months 3 weeks 5 days 20 hours ago) and read 20798 times:

Knots below 18000 ft, mach above.


Damn, this website is getting worse daily.
User currently offlineA330300 From United States of America, joined Nov 2005, 172 posts, RR: 0
Reply 4, posted (12 years 11 months 3 weeks 5 days 20 hours ago) and read 20779 times:

Also- The barometric pressure is set to a standard 29.92 aboe FL180.

User currently offlineCV640 From United States of America, joined Aug 2000, 952 posts, RR: 5
Reply 5, posted (12 years 11 months 3 weeks 5 days 19 hours ago) and read 20759 times:

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.

User currently offlinePositive rate From Australia, joined Sep 2001, 2143 posts, RR: 1
Reply 6, posted (12 years 11 months 3 weeks 5 days 18 hours ago) and read 20751 times:

"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.


User currently offlineNZ767 From New Zealand, joined Nov 2001, 1620 posts, RR: 1
Reply 7, posted (12 years 11 months 3 weeks 5 days 18 hours ago) and read 20744 times:

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


User currently offlineDerekF From United Kingdom, joined Feb 2001, 914 posts, RR: 0
Reply 8, posted (12 years 11 months 3 weeks 5 days 13 hours ago) and read 20714 times:

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.......
User currently offlineNZ767 From New Zealand, joined Nov 2001, 1620 posts, RR: 1
Reply 9, posted (12 years 11 months 3 weeks 5 days 13 hours ago) and read 20706 times:

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


User currently offlinePositive rate From Australia, joined Sep 2001, 2143 posts, RR: 1
Reply 10, posted (12 years 11 months 3 weeks 5 days 12 hours ago) and read 20699 times:

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

User currently offlineCathay Pacific From Australia, joined May 2000, 1864 posts, RR: 1
Reply 11, posted (12 years 11 months 3 weeks 5 days 11 hours ago) and read 20694 times:

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

 Smile/happy/getting dizzy Smile/happy/getting dizzy Smile/happy/getting dizzy Cathay Pacific...The Heart of Asia  Smile/happy/getting dizzy Smile/happy/getting dizzy Smile/happy/getting dizzy



cathay pacific, now you're really flying
User currently offlineNZ767 From New Zealand, joined Nov 2001, 1620 posts, RR: 1
Reply 12, posted (12 years 11 months 3 weeks 5 days 4 hours ago) and read 20654 times:

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


User currently offlineCanadi>nBoy From , joined Dec 1969, posts, RR:
Reply 13, posted (12 years 11 months 3 weeks 5 days 4 hours ago) and read 20650 times:

Planes fly at about 12,000 Knots an hour. It's true. Smile/happy/getting dizzy

User currently offlineJhooper From United States of America, joined Dec 2001, 6206 posts, RR: 12
Reply 14, posted (12 years 11 months 3 weeks 5 days 2 hours ago) and read 20641 times:

"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.
User currently offlineTom_eddf From Germany, joined Apr 2000, 452 posts, RR: 0
Reply 15, posted (12 years 11 months 3 weeks 5 days ago) and read 20628 times:

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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