3 ms·

Knots is used for ground speed as well I thought?

by mulmen 5y ago

adamm255 5y ago
I’ve never heard Knots used on land. Sea and Air yes!
- V-eHGsd_ 5y ago
  the ground speed of an aircraft is reported in kts.
- anamexis 5y ago
  Knots are indeed used when taxiing at airports.
- mulmen 5y ago
  Ground speed is speed over the ground. This includes when the aircraft is in the air. Airspeed is the speed of the plane through the air. These are not the same thing. Both are reported in knots.
jcrawfordor 5y ago
Really depends on the context. Usually things that were designed for pilots to use will display ground speed in knots since it's likely the pilot will be comparing against calculations done in knots. Things that were designed for the general public usually show mph since most people don't have a good sense of how fast a knot is. Taxi speeds are always written in knots, so I suppose you could say it is "official" (in terms of aircraft handbooks, airfield directories, etc) to use knots for ground speed. Of course the situation of an aircraft's ground speed while on the ground is sort of an edge case. On the topic of odd units, the operating handbooks for jet aircraft often use mach number for limits, which has some of the same properties as KIAS as far as being density dependent but is a little more precisely defined.
- mulmen 5y ago
  > So that when kph/mph is heard a pilot knows they're referencing ground speed, whereas knots is air speed. Who is using MPH/KPH in the course of flying a plane? Why would this ambiguity resolve to “that must be ground speed”? Why would there be ambiguity in a speed readout at all? Surely context and procedure should disambiguate this rather than units?
  - jcrawfordor 5y ago
    I'm not actually sure where that quote came from, but yes, there's not likely to be much confusion. Ground speed is usually displayed by some kind of computer, could be a glass panel or just an aviation GPS unit, and is usually marked "GS" or "Kts Ground." And it's sort of considered, philosophically, to be more a navigation thing than an actual flight instrument, since you only really pay attention to it in flight if you're doing navigation calculations.
    - mulmen 5y ago
      That quote came from the post I replied to originally. Beyond that I’m unsure of the source.

Knots is used for ground speed as well I thought?

by mulmen 5y ago

Knots is used for ground speed as well I thought?

adamm255 5y ago

I’ve never heard Knots used on land. Sea and Air yes!

V-eHGsd_ 5y ago
the ground speed of an aircraft is reported in kts.
anamexis 5y ago
Knots are indeed used when taxiing at airports.
mulmen 5y ago
Ground speed is speed over the ground. This includes when the aircraft is in the air. Airspeed is the speed of the plane through the air. These are not the same thing. Both are reported in knots.

jcrawfordor 5y ago

Really depends on the context. Usually things that were designed for pilots to use will display ground speed in knots since it's likely the pilot will be comparing against calculations done in knots. Things that were designed for the general public usually show mph since most people don't have a good sense of how fast a knot is. Taxi speeds are always written in knots, so I suppose you could say it is "official" (in terms of aircraft handbooks, airfield directories, etc) to use knots for ground speed. Of course the situation of an aircraft's ground speed while on the ground is sort of an edge case. On the topic of odd units, the operating handbooks for jet aircraft often use mach number for limits, which has some of the same properties as KIAS as far as being density dependent but is a little more precisely defined.

mulmen 5y ago
> So that when kph/mph is heard a pilot knows they're referencing ground speed, whereas knots is air speed. Who is using MPH/KPH in the course of flying a plane? Why would this ambiguity resolve to “that must be ground speed”? Why would there be ambiguity in a speed readout at all? Surely context and procedure should disambiguate this rather than units?
- jcrawfordor 5y ago
  I'm not actually sure where that quote came from, but yes, there's not likely to be much confusion. Ground speed is usually displayed by some kind of computer, could be a glass panel or just an aviation GPS unit, and is usually marked "GS" or "Kts Ground." And it's sort of considered, philosophically, to be more a navigation thing than an actual flight instrument, since you only really pay attention to it in flight if you're doing navigation calculations.
  - mulmen 5y ago
    That quote came from the post I replied to originally. Beyond that I’m unsure of the source.