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MPH or KTS?

MPH or KTS, Which do you prefer?

  • MPH

    Votes: 74 23.1%

  • KTS

    Votes: 247 76.9%
  • Total voters
    321
agirard7a

agirard7a

Well Known Member
Air speed indicator: knots or MPH?

Ok. Basic question. I am planning to purchase an air speed
indicator for my 9a. Should I get knots or MpH on the outer scale?
Thanks. Al
 
agirard7a said:
Ok. Basic question. I am planning to purchase an air speed
indicator for my 9a. Should I get knots or MpH on the outer scale?
Thanks. Al
Click to expand...

Nautical miles is the standard in US aviation although there seem to be many who will not accept this fact. Some even use just a number, without explaining that they are using a non-standard scale.
 
n5lp said:
Nautical miles is the standard in US aviation although there seem to be many who will not accept this fact. Some even use just a number, without explaining that they are using a non-standard scale.
Click to expand...

Larry is correct, Nautical is the US standard for current production planes. Older planes were all calibrated in MPH and for marketing reasons, most homebuilts advertise their speeds in MPH.

It comes down to personal choice and my choice was to use MPH on the outer scale and knots on the inner scale.
 
Maps are in nautical miles so ... speed in knots makes the math easier....
Otherwise you'll alyways being converting mph to knots.......
 
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ATC uses knots....

Maps are in nautical miles.

Lines of longitude are divided into nautical miles.

All military and airlines use knots.

Appraoch plates use nautical miles.

Egotistical aircraft marketing boobs use statute miles per hour because it sounds faster. If you want to be included in this elite group, by all means
use MPH! ;)
 
If you want a big number for speed you can use kilometer per hour (160 kts makes 300 km/h) but keep VSI in feet/mn because all other units will give you a smaller number.
I've always used KTS but in the plane in my club the airspeed inidcator has two scales, one for guys like me using knots, nautical miles... and another for those liking big numbers in km/h.
Regards
 
Another nosewheel/tailwheel discussion...

...and the Europeans haven't yet chimed in with their Kilometers per hour:)

FWIW....I grew up with MPH, so for me, it's MPH,

Best,
 
I would say KTS if you don't ever plan on flying with your RV buddies. MPH if you plan to do the every Saturday pancake breakfast. It just saves all the chatter on the radio..

"How far out are you?" - "78 miles" - "We'll I'm 92 so I'll see you there" - "Wait, is that nautical or statute miles?" - "What's your ground speed?" - "144" - "Knots?"

We've all heard it.
 
I did not vote.

I did not vote because I do not prefer one over the other. My RV has the outer scale in MPH and inner in Knots. I learned to fly in my fathers 1957 182A and Cessna's of that era had airspeed in MPH. That's all I new hence the reason the airspeed is in MPH in the RV. I use MPH for flying speed but am fluent in knots too. Anytime I reference speed or distance to ATC or other flying objects it's always in knots or nautical miles so there is no confusion. The world flys using nautical miles, we should too.

If you go with MPH make sure your fluent in Knots too. Remember when the tower asks you to report 5 out, it's in nautical miles, not statute.
 
Knots for sure

Knots. Aeronautical charts are nautical measure. Approach plates all use nautical units of measure. Speed assignments from ATC are in Knots. MPH are used when someone asks how fast your airplane is ;)
 
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speed!

I did not see km/hr in the survey. Using this unit of measurement would produce numbers we could brag about (i.e. 290 cruise).

:D
 
i voted mph because my asi outer scale is mph. i can compare that to 496 in mph for landing info and headwind info. my 430 and 250 are in knots. in actuality i would of voted both if it was available.
 
I have had several airplanes that had round dial airspeed indicators in both Knots and MPH. As an ex-military pilot I fly in knots (as do most professional pilots) and found the dual dials cluttered. So I pulled them and sent to a shop that redid the dial face in only knots. Much better looking ... to me.

One thing I have done is develop a spreadsheet for my checklist binder that cross-references TAS (or ground speed) in knots to fuel flow so it gives me statute miles per gallon. That is a good comparison to what autos get for MPG. I get warm and fuzzy feeling doing 170 knots and getting 24MPG+.
 
Speed mod

One of the easiest way to increase the speed of your plane is to change the ASI from kts to mph.:)

I think Vlad has the fastest plane as he is using kph.:rolleyes:

Kent
 
Knots to You!

Nautical miles should be used for all calculations and communications when one is committing aviation. When sequencing air traffic, and issuing separation clearances, ATC needs to know range and speed in knots.
Additionally, when approaching or departing an uncontrolled airport, and trying to sequence ourselves with other traffic, it is important that we all be working on the same page.
I too fly planes with ASI that are in MPH only. However, when stating my range and speed to ATC and other aircraft, I will always give it in knots in an attempt for standardization. If nothing else, when responding to inquiries by ATC or other aircraft, clarify that your speed or distance is given in statute miles.
 
MPH

MPH for me, only because I like the bigger number: 173 mph instead of 150knots. . I can still see knots on the inside range of the airspeed indicator. It's quick and easy to adjust the Dynon & GPS to display knots if I wanted.
 
I use mostly knots, however way back I originally used MPH. Coming back from Hot Springs, SD yesterday I had MPH set up in my EFIS as I was playing with my MPG. I had a 220 MPH GS and 30.7 mpg for much of the way. It was tough to convert KPG to MPG in my head. Dynon needs to have a way to have MPG without having everything in Statute miles.
 
MPH for airspeed, Kts for groundspeed

I prefer to use nautical miles for distance and knots for groundspeed, but like to stick with statute MPH for airspeed measurement since most aircraft I've flown in the past 10 years are old spamcans and I'm just more accustomed to airspeed in MPH.
 
MPH

MPH on the airspeed indicator because that's what Van has for published speeds (Vs, Vne, etc).
Knots on the GPS once established in cruise.
 
Knots

When speaking in aviation circles, I would think most people would like to come off as more "professional" than less so. With that in mind you would only use "knots", because that is what all professional pilots use. The only time it would be appropriate to use MPH, would be when you are trying to impress "chicks"! The only pilots that get a pass on this rule are Ag-Pilots, 'cause in my next life that's what I wanna come back as!:D
 
Dealing with multiple units of measurement for the same quantity is to invite confusion and error.

In isolation, one unit of measurement is as good as another and the choice is arbitrary. But in the real world, there are standards established (whether formal or de facto) in order to facilitate interoperability, in this case between different pilots, controllers, charts, databases, etc. (navigation and communication). You don't get to tell Jeppesen to send you charts in statute miles, nor do you get to tell ATC, "I prefer to communicate speeds in mph"...

Nautical miles and knots are the standard units of measurement for distance and speed in aviation in the United States and world-wide.
 
New scale

Personally, I settled on knots because of convention, professionalism and ATC.

However, after reading this thread, I'm considering changing my way of thinking. I've developed a unit of RV-specific speed measurement that equals 100 knots. I call it a "Mock", since it's not real.

Therefore, when cruising around at, say, 160kts, one would then refer to it as "1.6 Mock".

If the larger mph numbers are good for picking up chicks, just imagine what bragging, "Yeah, I can hit 1.78 Mock anytime I want to," would do for you! Eat your heart out, Maverick.

:D
 
N8RV said:
Personally, I settled on knots because of convention, professionalism and ATC.

However, after reading this thread, I'm considering changing my way of thinking. I've developed a unit of RV-specific speed measurement that equals 100 knots. I call it a "Mock", since it's not real.

Therefore, when cruising around at, say, 160kts, one would then refer to it as "1.6 Mock".

If the larger mph numbers are good for picking up chicks, just imagine what bragging, "Yeah, I can hit 1.78 Mock anytime I want to," would do for you! Eat your heart out, Maverick.

:D
Click to expand...

NOW THAT IS FUNNY! You've been staring at that HUD waaayyy to long!
 
For those who want big numbers just to impress the ignorant, I'd suggest switching to furlongs per fortnight. That way you'd only have to run at 162 knots to boast over a half a million furlongs per fortnight.:D

Also, for those mathematically challenged among us, just install an airspeed indicator calibrated in mph, fly in the neighborhood of 7500 feet, and read true airspeed in knots right off the dial.;)

PS: The Mock scale is VERY clever! I have some friends who have Mock as a surname, and they fly their 170 at Mock 1 most of the time...
 
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you guys are making a Mockery of this very important issue.

most of my friends are not pilots, so get confused easily. I use MPH as in it'll go 200mph or 15 minutes to travel from Townsend to Bozeman....blank look on their face, and respond that's only 1 beer instead of a 6pk.:D
 
I'm going with a scale from 1 to 10... "1" being stall speed, "10" being the speed where the tail comes off... :D
 
Yes

Mock it is. An advantage of this scale is that it can sorta be read directly off a standard AS indicator.
 
uh oh...what if you are reading it off a MPH A/S instead of a Kt A/S then the MOCK number will be wrong?
 
I say dual scale, Kts & Mph. It's better to have both because when flying with others, or moving from one plane to another. My 182 has dual scale, and it seems fine. I got a dual scale ASI for my RV-8.
ASI's with dual scale don't usually have the True Airspeed analog calculator, which is a nice option. Still, any portable GPS gives better Ground Speed, and your E6B can be used occationally to get True Airspeed.
Remeber all that old "Finger On Map" "Timed Legs", True Airspeed, Headwinds/Crosswind correction tables, Pressure altitude, Heck, a cross country flight was a math exersize!! :eek:
Now we just look at the GPS data. :rolleyes:
 
Left side of my airplane is knots. Ann's GPS (right side) is MPH. She goes faster than I do, but she has further to go.
We usually get there about the same time.
 
Then

elippse said:
Use whatever your car uses!
Click to expand...

You may as well sell your airplane and drive everywhere.

MPH really have noplace in aviation. It's akin to asking somebody what there airspeed is and they tell you groundspeed.
 
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Mel said:
Left side of my airplane is knots. Ann's GPS (right side) is MPH. She goes faster than I do, but she has further to go.
We usually get there about the same time.
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Our airplane is equipped with the same setup. We also get there about the same time. Must have something to do with both being RV6's.... :)

L.Adamson --- Rv6A
 
Knots

"MPH really have no place in aviation."
Good Call.
Please be professional. Use Knots
 
RV8iator said:
You may as well sell your airplane and drive everywhere.

MPH really have noplace in aviation. It's akin to asking somebody what there airspeed is and they tell you groundspeed.
Click to expand...

good grief... call it ft/sec, nanometers/millisecond or whatever you want and it will have ZERO relevance on how the airplane flies or how well it can be flown. As long as the plane has a nifty pink card from the FAA it will always have an equal place in aviation despite the assertion otherwise. OUT
 
mph vs kts

Does that mean we have to rip out the ASI's in all older airplanes (mph) and have them repainted or replaced? I don't mean to be harsh, but some of you guys sound like you'd make good bureaucrats! Maybe we could help FAA draft up a regulation requiring us all to have ASI's marked only in knots - no mph for us! Then write in stiff penalties (say $1000) for non-compliance. Of course we'd have to redo all old manuals and V speeds to get consistency. A lot of work. And we would have to hire a lot of new FAA personnel to monitor and enforce our new rule. Just kidding. Personally I like the dual scale ASI with TAS. These were in our Commanche, our Lance and one's going in the -8. I think they're very handy. Must admit though that I'm not a professional pilot.
 
Bill Dicus said:
Does that mean we have to rip out the ASI's in all older airplanes (mph) and have them repainted or replaced? I don't mean to be harsh, but some of you guys sound like you'd make good bureaucrats! Maybe we could help FAA draft up a regulation requiring us all to have ASI's marked only in knots - no mph for us! Then write in stiff penalties (say $1000) for non-compliance. Of course we'd have to redo all old manuals and V speeds to get consistency. A lot of work. And we would have to hire a lot of new FAA personnel to monitor and enforce our new rule. Just kidding. Personally I like the dual scale ASI with TAS. These were in our Commanche, our Lance and one's going in the -8. I think they're very handy. Must admit though that I'm not a professional pilot.
Click to expand...

Bill,
I do not believe that anyone would endorse what you hypothesize in your posting. From my perspective, I would just like everyone to be on the same page for position and WX reports. The standard measurement is nautical for WX, ATC, etc., so it is just matter of safety and clarity.
Quite frankly, I don't believe that anyone cares what you use for your personal pleasure. If the bigger numbers give you a warm fuzzy...have at it. But I for one (and ATC too, I am sure) would appreciate it if everyone used the standard nautical scale for all reporting.
"Thats all I have to say about that"...F. Gump
 
kts, mph and km/hr

Imagine us poor Canucks. When somebody asks how fast airplanes go, and you say knots, they'll look at you funny.
I am constantly converting knots into km/hr during conversations with non-pilots. As a general rule, 100kts = 115mph = 180km/hr. Good enough for conversation.

Now my RV-8 is going to be in knots for three reasons.
1. It's what I am used to.
2. 1' of latitude is 1 nautical mile.
3. Every aeronautical map uses nautical miles excusively.
 
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