what kind of plane is this?

[Oddball]

A glass panel C-150!! 

[Baradium]

VLJ = very little jets

These guys are really annoying.  We want to instate a rule where you cannot fly higher than your airspeed.  FL300 and 190 kts is just wrong, makes a nice speed bump.

wow, I thought they's be faster!! what's the point of paying a million bucks and end up with turbines just to go the speed of a Mooney ?!?! 

too bad they're POS's ! I thought they looked cool.
maybe in the future they'll come up with something similar that actually works....

As Chris said, it's actually still much faster than a mooney... but it's actually more like .5 mach (and maybe a fair bit less than that)....  .72 mach at 300 is still well over 200 kias.   Actually, .6 mach is still well over 200 kias as well, I seem to recall.  Today .76 mach was around 290kias at FL280 for comparison.

We can't go that slow that high (starting to really see the effect of coffin corner there, no?)   but I'd say it's probably around 280-300 ktas.  The problem of course is that everyone else is doing well over 400ktas at that altitude.  We're usually filed at around 430-440 ktas and that is for .74 mach.  That is usually as slow as any airliners will go unless they're trying to save fuel (our best economy seems to usually be in the .62-.65 mach range).

That's where the problem comes in,  those things are not only slow at max speed, but they tend to be slower than the other traffic is even capable of going.

As far as what 190kts is in mach at that altitude range...  I should get up close to that altitude going to MN tomorrow,  if I remember I'll get the computer to tell me what it is.

[Frank N. O.]

Mach change according to altitude? I thought the only variable was the density of air and temperature which dictates how fast sound can travel and just as I started writing this I think I may have actually answered my own question. But can you ATC's use a mach-number when you're seeing the planes move in relation to the ground?

Frank

[Louis]

It does because pressure and density change with altitude, as does temperature.
I'm not an ATC but afaik, they use Mach numbers much like IAS lower for spacing purposes.

Current ATC procedures, and most avionics systems, are not set up to work with groundspeed as a "target" parameter. By this I mean a controller would not ask a pilot to maintain x knots GS. Same controller could however ask for x Mach or x IAS based on winds aloft to obtain a desired GS.

Louis

[The_Muppet]

But did they see the blue screen of death?

Sounds like the stories I read about the Aegis Cruisers running on Windows NT.  From this wikipedia entry...

...Atlantic Fleet officials acknowledged that the Yorktown experienced what they termed “an engineering local area network casualty.”...

At least they weren't running Vista on it. That woulda been messy.
 

"You have chosen to Launch a RIM-66M Missile.  Are you sure you want to fire this missile?  <Ok> <Cancel>"

... clicks Ok...

"The act of firing this missile may cause injury or death to the target, are you sure you want to fire this missile?  <Ok> <Cancel>"

And so on...

[Fabo]

Frankly, I like Russian style more

http://www.youtube.com/v/86uithwaJOk

[Rooster Cruiser]

IIRC, I believe that movie is titled, "Adventures in International Fishing".  My wife brought the DVD home from the Rodina a few years ago.  Hehe.  Very funny movie!   

[Fabo]

Very good series, indeed. I took the name from wikipedia, so you may be right.

[undatc]

It does because pressure and density change with altitude, as does temperature.
I'm not an ATC but afaik, they use Mach numbers much like IAS lower for spacing purposes.

Current ATC procedures, and most avionics systems, are not set up to work with groundspeed as a "target" parameter. By this I mean a controller would not ask a pilot to maintain x knots GS. Same controller could however ask for x Mach or x IAS based on winds aloft to obtain a desired GS.

Louis

The HOST/DARC system which runs the National Airspace System utilizes several different things when pertaining to an aircraft speed.  Initially the HOST software will take the filed airspeed and base its calculations on descent/climb/cruise speed based off that.  If the airspeed is off by a lot, the flight plan in the computer system will process either faster or slower than it should.  When the flight plan no longer correlates with the data being furnished by the radar system, a time update is issued and the flight plan re-adapts.  Sometimes when the system is kicking out a lot of time updates we well ask the aircraft to verify his airspeed, and we will modify his flight plan so it process' better.

In addition to that, on the radar scope the ground speed of an aircraft is always displayed.  There is no other option to have IAS displayed.  We can ask the pilot to tell us what his IAS is, however when aircraft climb higher, all IAS tend to get close to 250kts (this has to due with the air molecules entering the pitot static system of an aircraft).  As an aircraft usually climbs out of FL 240, ATC likes to transition to mach numbers as it better reflects how fast the aircraft is actually moving.  As a general rule of thumb, every .01 in mach number equals about 5kts.  This will change as well with altitude, mach .77 at FL240 is probably closer to 300kts, where as .77 at FL400 is closer to 250kts.  This can become an issue when sequencing aircraft in the arrival phase of flight with assigned airspeeds.

Hopefully that helps a bit.  Its late and i'm tired.

[Baradium]

You guys use mach that low?  We don't transition to using mach until we get to around 28 and it seems that ATC usually gives us either IAS or mach at F280 and IAS below that.

BTW, at FL280 190kias is .49 mach.  At 310 190kias is .52 mach.


A big reason ground speed isn't used is because ground speed doesn't have much to do with what the aircraft is capable of achieving. 100kt winds either direction make a big difference on whether we can actually maintain a speed.

Our filed speeds above 270 translate to .74 mach (below that either 310 and then 300 KIAS depending on the altitude).  I happen to have my flight kit with me becuase I'm not going back to domicile for the start of my next trip and have an old flight plan handy... at FL260 we were filed at 446 KTAS.  That should be 310kias, and it should be almost .74 mach (they are getting pretty close at that altitude, it's probably around .72).

I think .70 mach usually gets to 250 indicated around FL330 or so.


What Chris also left out about arrivals is the big change in TAS that you get as you descend.  We lose a lot of our ground speed, even when exiting headwinds, as we get lower... this means that you start to get  much closer to the guy in front of you as he descends because suddenly you are going much faster.

[Jupiter]

It does because pressure and density change with altitude, as does temperature.

Just to continue on this, the mach number is actually only dependant on temperature, because a=SQRT(gamma*R*T) with a being the speed of sound, and both gamma and R are constants, so the only variable is the temperature. Pressure and air density also do change, but these are correlated with temperature (p=rho*R*T), making temperature the only needed variable to determine the speed of sound.
Hope I didn't get too technical here...

Now off to my flight & orbital mechanics exam...