Why does my C172 POH use "mph"??

[Lawson_Stone]

Do you always choose the small things to argue about?

If so, you'll fit in fine here, just as soon as you stop try to not offend people.

I didn't think he was offensive. He was responding to a patronizing, condescending comment someone made about his "playing" X-Plane, a simulation program that is used on commercial simulators and in some versions is accepted as a training program. I was glad to see him stick up for himself on that point.

 

[guest user]

I didn't think he was offensive. He was responding to a patronizing, condescending comment someone made about his "playing" X-Plane, a simulation program that is used on commercial simulators and in some versions is accepted as a training program. I was glad to see him stick up for himself on that point.

I never said he was offensive. Matter of fact, I said:

... just as soon as you stop try to not offend people.

My point was that comments like the below are not needed here at PoA. The PoA regulars tend to be of the type of person on whom niceties are lost. People with 'sensitivities' tend to not last very long.

Respectfully ...

No offense to anyone ...

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As to the topic of X-Plane, would you be surprised to know that I also use the program? I know the value of it, yet you're not going to find me feeling the need to defend it against those who see it merely as a game. I know the value, they do not. Defending my choice to use it until they acknowledge my deep wisdom in choosing to use this as a training aid is not on my list of things to do. Why? Because 1) it will never happen and 2) the argument is as old as low wing vs high wing. I use X-Plane, if you don't, great. If you do, great. Done.

This gives me more time to play with my toy.

 

[Pilawt]

The member companies of General Aviation Manufacturers Assn. finally agreed to make the switch from mph to knots as primary speed unit in the early 1970s. Cessna implemented the switch with the 1976 model year; Piper and Beech followed in 1977.

American Champion still quotes performance in mph.

 

[sarangan]

I obtained a new (for real), original POH for the 172M that I've just started flying.
I'm so used to using knots, and every reference to speed is in mph.

Airspeed is so critical I don't want any confusion and doing conversions in my head while I'm flying and want to maintain consistency here. Shouldn't I go through this POH and mark everything up in knots? I thought knots was universal in marine and aviation...

The white, green and yellow arcs tell you nearly everything. The unit of measure is really not important except for certain instances like arrival procedures where you have to maintain a specific airspeed. The few other unmarked speeds like Va and Vle could be easily marked without specifying any units.

 

[Lindberg]

I didn't think he was offensive. He was responding to a patronizing, condescending comment someone made about his "playing" X-Plane, a simulation program that is used on commercial simulators and in some versions is accepted as a training program. I was glad to see him stick up for himself on that point.

Great, it's not a game. You don't "play" it. Ok, cool. Maybe it can even be a valuable teaching tool, maybe not. But based on what he's posted here, this particular student is learning bad habits from it and it's impeding his learning to fly actual airplanes.

 

[Lawson_Stone]

Great, it's not a game. You don't "play" it. Ok, cool. Maybe it can even be a valuable teaching tool, maybe not. But based on what he's posted here, this particular student is learning bad habits from it and it's impeding his learning to fly actual airplanes.

That's inferring a lot from just a few lines the OP wrote. Maybe be a little less doctrinaire and spend a bit more energy listening than just pounding out a judgment. Just my opinion, worth what you paid for it.

 

[Jim K]

The member companies of General Aviation Manufacturers Assn. finally agreed to make the switch from mph to knots as primary speed unit in the early 1970s. Cessna implemented the switch with the 1976 model year; Piper and Beech followed in 1977.

American Champion still quotes performance in mph.

So of course I wound up flying a 1976 piper and a 1975 cessna

 

[Lawson_Stone]

I never said he was offensive. Matter of fact, I said:


My point was that comments like the below are not needed here at PoA. The PoA regulars tend to be of the type of person on whom niceties are lost. People with 'sensitivities' tend to not last very long.





----------------------------

As to the topic of X-Plane, would you be surprised to know that I also use the program? I know the value of it, yet you're not going to find me feeling the need to defend it against those who see it merely as a game. I know the value, they do not. Defending my choice to use it until they acknowledge my deep wisdom in choosing to use this as a training aid is not on my list of things to do. Why? Because 1) it will never happen and 2) the argument is as old as low wing vs high wing. I use X-Plane, if you don't, great. If you do, great. Done.

This gives me more time to play with my toy.

I misconstrued. Not the first time, and I fear, not the last. Thanks for patiently explaining.

 

[Lindberg]

That's inferring a lot from just a few lines the OP wrote. Maybe be a little less doctrinaire and spend a bit more energy listening than just pounding out a judgment. Just my opinion, worth what you paid for it.

Being too doctrinaire is exactly the OPs problem. He needs to forget the ASI and feel the airplane. You can't do that on a computer, and he's trying to fly the airplane like his computer.

 

[Lawson_Stone]

Being too doctrinaire is exactly the OPs problem. He needs to forget the ASI and feel the airplane. You can't do that on a computer, and he's trying to fly the airplane like his computer.

Maybe. But you're reading a lot more into the original post than I am. I saw it just as a loose comparison, not a rigid attempt to make one like the other. But you might be right. I just think you're being too harsh on him, that's all. But hey, sitting behind a keyboard when there are no consequences, we can all be more harsh than we should be I suppose.

 

[dmspilot]

I obtained a new (for real), original POH for the 172M that I've just started flying.
I'm so used to using knots, and every reference to speed is in mph.

Airspeed is so critical I don't want any confusion and doing conversions in my head while I'm flying and want to maintain consistency here. Shouldn't I go through this POH and mark everything up in knots? I thought knots was universal in marine and aviation...

You don't do conversions in your head. Nor do you change your POH. You use the specified speed in the specified unit. If the book says Vy is 80mph that's what you use. It's not difficult.

 

[asicer]

I can attest that if one memorizes knots and then fails to notice the airspeed indicator is MPH that the landing distance is reduced considerably.

 

[rhkennerly]

Airspeed indicator shows both knots and mph, just like the one I fly in the X-Plane sim.

actually, you err in thinking that your game mirrors the real world in any meaningful way. The OP reference aircraft, the Cessna 172 M variant, was produced early to mid-70s and does not have both knots & mph markings on the AS indicator, only mph. It also probably has an ADF & DME, if we’ll-equipped.

 

[luvflyin]

I can attest that if one memorizes knots and then fails to notice the airspeed indicator is MPH that the landing distance is reduced considerably.

Well gee, seeing as how it's confession time. BTDT. Just once. I was thinking for a second the stall horn needs to be calibrated.

 

[Pilawt]

The OP reference aircraft, the Cessna 172 M variant, was produced early to mid-70s and does not have both knots & mph markings on the AS indicator, only mph.

The OEM C-172M airspeed indicator (1973-75) did not have a full knots scale, but there was a small window around the needle through which the knots value could be seen on the inner scale.



For the 1976 model year onward, knots was on the main scale, and mph was visible through the window.

 

[guest user]

That would certainly be annoying to try to keep track of, especially as they flipped the markings, but no doubt easy to forget to double check MPH/KNOTS

At least Piper gave you the full secondary (knots in this case) scale.

 

[Pilawt]

That would certainly be annoying to try to keep track of, especially as they flipped the markings, but no doubt easy to forget to double check MPH/KNOTS

True, but if you were using the OEM C-172 gauges, at any given speed the needle would point the same direction on the face of the instrument, and relative to the colored arcs, regardless what units of measure were used.

 

[guest user]

I agree that if you ignored the numbers and did the "the needle should point about <there>" it would all work out.

 

[rhkennerly]

Well gee, seeing as how it's confession time. BTDT. Just once. I was thinking for a second the stall horn needs to be calibrated.

That’s okay. The other day I wondered, just briefly, if I should let the 200 lbs out of the compressor before I picked it up.

 

[asicer]

Well gee, seeing as how it's confession time. BTDT. Just once. I was thinking for a second the stall horn needs to be calibrated.

I was wondering how it was that at a 2500ft runway I could make the first turn off without using the brakes.

 

[Dan Thomas]

actually, you err in thinking that your game mirrors the real world in any meaningful way. The OP reference aircraft, the Cessna 172 M variant, was produced early to mid-70s and does not have both knots & mph markings on the AS indicator, only mph.

The 1976 172M had a knotmeter. We've already been there.