Silly question I know but anybody have a good reason for switching to kts?

I’ve always been a mph guy, I’m not flying a boat dammit, but it’s getting somewhat annoying since it seems like everyone else is using kts. I’m constantly having to convert units to compare numbers with other planes. Besides mph makes it seem like my plane cruises pretty fast...

Why not just get an airspeed indicator that has both on there ?

niente qui

whee wrote:Silly question I know but anybody have a good reason for switching to kts?

I’ve always been a mph guy, I’m not flying a boat dammit, but it’s getting somewhat annoying since it seems like everyone else is using kts. I’m constantly having to convert units to compare numbers with other planes. Besides mph makes it seem like my plane cruises pretty fast...

So what’s the problem? Just the conversions?

There are 3 types of people. Those that are good at arithmetic and those that aren’t.

dogpilot wrote:The reason we use knots has become somewhat obscure. Before the days of magenta lines on screens we actually had to use paper maps. Sometimes we did this in places that had no actual navaids. So 1 nautical mile was one arc second on the map. So we could dead rekon our position with some idea of where we might be. The nautical mile actually represented something we could relate to, not a wavelength of a hydrogen atom, or three barleycorns, which I never seem to have available when I need it.

So, while MPH might seem marginally useful, when all those satellites go dark from a solar storm or some pissy conflict when the powers decide to switch them off. Be thankful you have knots, you may need it someday...

Not to punch holes in your theory, but where exactly are people going to find a paper chart? I haven't seen a chart for sale in five years or more.

Hammer wrote:

dogpilot wrote:The reason we use knots has become somewhat obscure. Before the days of magenta lines on screens we actually had to use paper maps. Sometimes we did this in places that had no actual navaids. So 1 nautical mile was one arc second on the map. So we could dead rekon our position with some idea of where we might be. The nautical mile actually represented something we could relate to, not a wavelength of a hydrogen atom, or three barleycorns, which I never seem to have available when I need it.

So, while MPH might seem marginally useful, when all those satellites go dark from a solar storm or some pissy conflict when the powers decide to switch them off. Be thankful you have knots, you may need it someday...

Not to punch holes in your theory, but where exactly are people going to find a paper chart? I haven't seen a chart for sale in five years or more.

Amazon Prime has sectional charts, free delivery!


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I worry less about a satellite apocalypse than I do about batteries and electrical gremlins. I subscribe to Foreflight but still buy sectionals for big trips in case the iPad dies while I'm over unfamiliar terrain out of range of the ever-thinning number of VORTACs. I've had iPads shut down from heat and I've also had them down in the single digit percentages of battery with the display turned way down low after a 4 hour flight, even with a recharging brick.

I keep the charts with the E6B in the side pocket. I have two GPSs now, but I've also had enough electrical gremlins over time that I want paper with me when I'm traveling. When it comes to pilotage, knots are easier.


CAVU

I fly airplanes with airspeed indicators that are in MPH and others with airspeed indicators that show KTS.

I set up any GPS displays to correspond to whichever units the airspeed indicator is using.

Whee since you are experimental you could have chosen what you wanted at the time your operating specifications were issued. You chose mph so your limitations should be in mph and your airspeed indicator primary scale should be in mph. Same if you had chosen kts. For a certified aircraft it should be in what the manufacturer used for airspeed units at the time the type certificate was issued and that may have been determined by regulation, I am just too lazy to look it up. So for example on my 170b which has a max flap speed of 100 mph and a white arc with the upper limit at 100 mph I would need a placard with the new flap limit of 87 kts and a white arc upper limit of 87 kts. I don't believe on a certified aircraft there is any approved data to change from mph to kts, for experimental the builder probably has the option to change his operating specifications to use the other speed unit, and have those changes approved.

just my opinion, Tim

Troy Hamon wrote:I fly airplanes with airspeed indicators that are in MPH and others with airspeed indicators that show KTS.

I set up any GPS displays to correspond to whichever units the airspeed indicator is using.

What he said. On the idea of an ASI having both speeds, and my 185 does, the I think it only fair that my altimeter have fathoms too.

I be decided, since I understand mph, I’m having the 185’ s altimeter recalibrated and painted in mph, including having the white and green stripe repainted to match RSTOL numbers.

low rider wrote:Why not just get an airspeed indicator that has both on there ?

My EFIS will only show one or the other. But really the issue is constantly converting back and forth. It's not hard but is annoying.

dogpilot wrote:The reason we use knots has become somewhat obscure. Before the days of magenta lines on screens we actually had to use paper maps. Sometimes we did this in places that had no actual navaids. So 1 nautical mile was one arc second on the map. So we could dead rekon our position with some idea of where we might be. The nautical mile actually represented something we could relate to, not a wavelength of a hydrogen atom, or three barleycorns, which I never seem to have available when I need it.

So, while MPH might seem marginally useful, when all those satellites go dark from a solar storm or some pissy conflict when the powers decide to switch them off. Be thankful you have knots, you may need it someday...

Hmm, Interesting history. Now I need to google arc seconds.

Paddles wrote:So what’s the problem? Just the conversions?

There are 3 types of people. Those that are good at arithmetic and those that aren’t.

Haha! The conversions are easy but annoying. Akin to a couple engineers talking but one in SI units and the other in metric.

bat443 wrote:Whee since you are experimental you could have chosen what you wanted at the time your operating specifications were issued. You chose mph so your limitations should be in mph and your airspeed indicator primary scale should be in mph. Same if you had chosen kts. For a certified aircraft it should be in what the manufacturer used for airspeed units at the time the type certificate was issued and that may have been determined by regulation, I am just too lazy to look it up. So for example on my 170b which has a max flap speed of 100 mph and a white arc with the upper limit at 100 mph I would need a placard with the new flap limit of 87 kts and a white arc upper limit of 87 kts. I don't believe on a certified aircraft there is any approved data to change from mph to kts, for experimental the builder probably has the option to change his operating specifications to use the other speed unit, and have those changes approved.

just my opinion, Tim

I'll have to check my Operating Limitations; the DAR never asked what units we were going to use so I'm not sure how he would have known what units to write them in.

Along with the minutes/seconds on a chart, winds aloft and on the ground are reported in knots.This is not a reason to go to knots, but might be a reason to calculate using knots. While teaching students XC flight planning, I generally have them convert their true airspeed to knots since everything else is in knots (plotters, wind data, etc).

I fly enough various types/ages of airplanes that I find it's very easy to think/speak in both, whats on the ASI or groundspeed readout doesn't change much for me.

A few things got me thinking about this. First was a fairly precise discussion about landing technique in my airplane. Some guys talking in knots with others in mph. It made for a convoluted discussion because you can't just SWAG the conversion when your talking about 30kts or whatever speed puts you on the cusp of a stall.

Seconds things is I've been flying with a few different guys and their planes are in knots. So when we plan to meet up but fail to convey units it takes a bit to find each other.

I've been flight planning using skyvector which is in knots. And like has been said, weather reports are in knots. Seems silly to do all the flight planning in knots but fly in mph when changing units is only a few button pushes away.

Thanks for the thoughts guys.

Hammer wrote:Not to punch holes in your theory, but where exactly are people going to find a paper chart? I haven't seen a chart for sale in five years or more.

I use paper sectionals. What else are you supposed to use? duh.

Hammer wrote:

dogpilot wrote:The reason we use knots has become somewhat obscure. Before the days of magenta lines on screens we actually had to use paper maps. Sometimes we did this in places that had no actual navaids. So 1 nautical mile was one arc second on the map. So we could dead rekon our position with some idea of where we might be. The nautical mile actually represented something we could relate to, not a wavelength of a hydrogen atom, or three barleycorns, which I never seem to have available when I need it.

So, while MPH might seem marginally useful, when all those satellites go dark from a solar storm or some pissy conflict when the powers decide to switch them off. Be thankful you have knots, you may need it someday...

Not to punch holes in your theory, but where exactly are people going to find a paper chart? I haven't seen a chart for sale in five years or more.

Amazon Prime has sectional charts, free delivery!


Sent from my iPhone using Tapatalk

Halestorm wrote:

Hammer wrote:

dogpilot wrote:The reason we use knots has become somewhat obscure. Before the days of magenta lines on screens we actually had to use paper maps. Sometimes we did this in places that had no actual navaids. So 1 nautical mile was one arc second on the map. So we could dead rekon our position with some idea of where we might be. The nautical mile actually represented something we could relate to, not a wavelength of a hydrogen atom, or three barleycorns, which I never seem to have available when I need it.

So, while MPH might seem marginally useful, when all those satellites go dark from a solar storm or some pissy conflict when the powers decide to switch them off. Be thankful you have knots, you may need it someday...

Not to punch holes in your theory, but where exactly are people going to find a paper chart? I haven't seen a chart for sale in five years or more.

Amazon Prime has sectional charts, free delivery!


Sent from my iPhone using Tapatalk

Not to punch holes in the theory of the guy punching holes in the other theory but; if the reason for ordering paper charts from Amazon is satellites going dark...how is Amazon’s drone going to find my house?

I placed a laminated paper tape “nomogram” converting mph to kts so as to avoid all that pesky thinking:

Umm, your ASI is in mph and your tape converts it to mph as if the ASI was in knots.

For flight planning and cruising I use knots. All of the information on the GPS/NAV/Ipad is set up that way so no conversion is needed. Also indicated airspeed at altitude is not really relevant for navigation. I use MPH for my V speeds because I fly a pre 1974 airplane. It's just easier to remember the speeds on the outside of the instrument dial. When flying post 1974 airplanes I just learn the V speeds in knots. On the thread drift topic of paper vs electronic charts - I feel there is enough redundancy with having an Iphone, Ipad, and 2 GPS units in the plane all with maps. I never liked folding a sectional in my lap. I do keep a full charged 20mAMP battery in my airplane to insure that I never run out of juice. I live in a cooler climate and my Ipad mini has never overheated.


Josh

There are 3 types of people. Those that are good at arithmetic and those that aren’t.[/quote]

I just spit a drink all over my laptop...