Aircrafts mach speed??

[kmacka]

I was listening to New York Center's ARTCC UHF frequencies earlier and heard the controllers asking for the aircrafts mach speed. Now does this mean that this aircraft was a military aircraft or do all aircraft report mach speed? I believe the aircraft was in the vicinity of 37,000 feet.

 

[Colin9690]

I was listening to New York Center's ARTCC UHF frequencies earlier and heard the controllers asking for the aircrafts mach speed. Now does this mean that this aircraft was a military aircraft or do all aircraft report mach speed? I believe the aircraft was in the vicinity of 37,000 feet.

No, it doesn't need to be military. Most commercial jets have not only an airspeed indicator (in knots), but they also have a Mach indicator. So no, it doesn't mean it's a military aircraft.

 

[kmacka]

Ok thanks for the reply.

Now another question on aircraft speed. What is the max speed a military aircraft can fly while in flight on just a normal trip, not meaning emergency or anything.

 

[Colin9690]

Ok thanks for the reply.

Now another question on aircraft speed. What is the max speed a military aircraft can fly while in flight on just a normal trip, not meaning emergency or anything.

I believe they need clearance to fly at a cetain speed at a cetain altitude, but I'm not sure exactly how fast they need a clearance for. For example, you can't have a fighter going 800 knots at 5000 feet, an altitude littered with 90 knot Cessnas and Pipers. Maybe someone else knows the exact answer to your question.

 

[nycrich]

"heard the controllers asking for the aircrafts mach speed'

There are different classes of airspace. Mach numbers are used for High Altitude/Enroute flights and Oceanic flights. Usually this means when the aircraft is at cruising. Airspeed readings can vary with temp/pressure locally. Mach number is in reference to speed of sound at a standard preset pressure. Controllers find it easier to use example, "mach .82" than using longer numbers which could be lead to confusion as to what units it could be since the US does not use metric units as the rest of the world for commercial aviation.
Controllers also have a listing of mach numbers at their scopes for each category of aircraft so they can be assigned speeds within their opearating limits for spacing,etc

 

[SAR923]

I think the rules vary if it's noted as a military operations area on nav maps or not. MOA's allow much greater freedom of movement than normal civilian airspace. OTOH, I am about 15 miles from Maxwell AFB and almost every night, we have C-130's obviously training for covert ops flying right over the house. We are directly in the flight path for Prattville Airport and there will usually be a flight of 3-4 C-130's, completely blacked out, flying awfully close to if not below 500 feet AGL. Prattville is uncontrolled and I've heard pilots come up on the unicom asking about traffic and never heard a response from the C-130's. I'm amazed some poor sap in a 172 hasn't plowed into one of these flights yet.

 

[Newark777]

Once commercial flights get above around FL180, they generally start using their Mach number instead of knots for their speed. Most airliners operate in the Mach 0.80-0.85 range while at cruise.

 

[SouthSoundScanner]

What is mach 0.80 in MPH ?

 

[Lexxx]

Mach 1 is the speed of sound, so mach .75 would be 3/4 the speed of sound. At sea level I believe the speed of sound is about 750 mph. It varies with temperature. The higher the altitude the lower the temperature of course.

Aircraft may fly as fast as an indicated air speed of 250 knots below 10,000 feet. Once they get within 10 miles of a controlled airport and below 3000 feet above ground that max speed lowers to 200k.

 

[jtsjc1]

Airliners will also show ground speed and TAS on the Primary Flight Display. Convert the GS from kts to mph. The speed of the a/c shadow across the ground.

 

[musicman476]

What is mach 0.80 in MPH ?

It's about 609 mph or about 529 knots.

-DT

 

[Newark777]

It's about 609 mph or about 529 knots.

-DT

Not necessarily. As others have said, an object's Mach number is its speed relative to the speed of sound in the surrounding medium, and the speed of sound varies with environmental factors. Very simply, your Mach number = (your speed/speed of sound of the medium you're traveling through).

 

[Yokoshibu]

environmental factors effecting mach include: Temperature, Pressure, and to a limited extent Relative Humidity.
most aircraft display KIAS and Mach, KIAS has to be converted to find TAS Ground speed is nothing more than TAS with winds factored into the equation.
So you can travel faster than the speed of sound when looking at the ground speed alone but TAS is sitting at mach .92


As far as speed limits go below 10,000ft in the united states you must maintain below 250 knots or your minimum controllable airspeed for the really fast jets..... like the sr-71.

there are low altitude high speed corridors for military training routes.... Do you remember 3-4 years ago an F-16 in Florida smooshed a C-172? that happened in a high speed corridor. I have seen videos of near misses in high speed corridors that have made me cringe - all of them have been from private pilots not talking or squawking. For the life of me I don't know why private pilots fly in well known military training routes thinking nothing will happen. After ATC clears an aircraft to enter an MTR they do not necessarily have to provide traffic avoidance / alerting services to the military traffic.

 

[start]

Often times ATC will ask aircrafts their mach numbers for traffic separation. For example, you’ll have three different aircrafts on the BSR2 arrival into San Francisco. When the planes come close to one another they request the pilots to either speed up or slow down. You also hear ATC requesting mach numbers when crossing the oceanic airspaces to keep separation.

All planes flying within the United States must maintain 250 knots below 10,000 feet. There is no “clearance speeds” for planes but they typically operate at .80 to .85 mach speeds.

 

[Declared_Hostile]

Ok thanks for the reply.

Now another question on aircraft speed. What is the max speed a military aircraft can fly while in flight on just a normal trip, not meaning emergency or anything.

They accidentally slip past the sound barrier occasionally below certain altitudes and cause a ruckus in my neck of the woods. I've heard F-16s, and F-15s both do it during ACM training in the MOAs near where I live.

Recently Boeing was flogging an aircraft around the airspace with oodles and gobs of go-fast and gave the countryside far and wide a thorough sonic thumping. Caused a mild panic in some quarters. I thought it was all sorts of cool myself. I heard one last winter that had the whole county running around looking for exploding meth labs or something.

Sometimes the base will acknowledge they had an “oops” and sometimes you never hear anything about it.

 

[Mark]

Sometimes here in Maryland will hear Test aircraft out of Pax River NAS with Base usually F-18's and when they do go supersonic they announce it on radio but almost always at high altitude 30k plus and over southern Ches Bay or offshore Atlantic Ocean in known restricted test areas.
You would never know unless they announced it.
I'm sure some offshore fishing boats have heard them though.

Mark