Foreflight True Airspeed Value?

itsjames2011

itsjames2011

Pre-takeoff checklist
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James
Hey everyone,

When setting up the ForeFlight advisor, it asks you to the plug in all of the information for your airplane. One of the values it asks for is the true airspeed and I'm wondering what number to use there as the idea of there being one true airspeed makes absolutely no sense to me.

I fly a 1967 Cessna 172H with a Continental O-300.

James
 
I'm thinking this would be the airspeed you would report on an IFR flight plan filing.

The aircraft info you put into FF is used to populate the pertinent fields when you do "file and brief". But it also uses the data to compute time en route and estimated fuel usage.
 
AggieMike88 said:
I'm thinking this would be the airspeed you would report on an IFR flight plan filing.

The aircraft info you put into FF is used to populate the pertinent fields when you do "file and brief". But it also uses the data to compute time en route and estimated fuel usage.
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I simply wanted it in there so that I will get a semi decent idea of the actual cruise flight time. It's really too bad that ForeFlight can't calculate climb out and descent.

I don't have an insturment ticket so I have no idea what airspeed would be put on the flight plan. Perhaps you could point me toward finding that info??
 
There are some good templates on fltplan.com
 
Well, what is the airplane's true air speed when you fly it? Maybe 100 knots or 95 or 105? Something like that. Depends on the airplane and how you fly it.
 
Just put in whatever TAS you normally cruise at.
 
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TAS = IAS + 2% per 1000' altitude. Is a good rough calculation estimate.
 
itsjames2011 said:
I simply wanted it in there so that I will get a semi decent idea of the actual cruise flight time. It's really too bad that ForeFlight can't calculate climb out and descent.

I don't have an insturment ticket so I have no idea what airspeed would be put on the flight plan. Perhaps you could point me toward finding that info??
Click to expand...

Look in the POH, take an average cruise altitude and cruise power setting. Even without cruise/descent calcs, FF is usually within a few minutes of the actual time on the vast majority of my flights.
 
There must be some reason, but I've never been able to figure out why flight planners use TAS for their flight planning and route/altitude optimization features. Wouldn't it make more sense to use CAS? Shouldn't the TAS increaes with altitude be a factor?
 
How does it make sense to use CAS for flight planning purposes?

Doing 160 KCAS at 1000' you cover *roughly* 160 nautical miles in 1 hour of your flight.
Doing 160 KCAS at 19000' you cover *roughly* 220 nautical miles in 1 hour of your flight.

For flight planing purposes, every phase of flight basically relies on the amount of ground you cover in a certain time, it makes no sense using Calibrated Air Speed for this, since without using altitude to convert it to True Air Speed, it's essentially meaningless (for flight planing purposes, that is).
 
You can find TAS in the POH. Not sure why this is even a discussion.
 
I use 135 just because I know that is in practice what I get. 10% is the tolerance anyhow (though I've never seen ATC really care in this day and age of near perpetual radar contact).

The recent annoyace is that I upgraded FF on my iPhone recently and suddenly it stopped filing flight plans. In my aircraft profile I had my plane type as navi/G. Apparently it gags on it being lower case NOW (didn't used to and the FAA doesn't give a hoot). I had to switch it to NAVI.
 
Use the airspeed from the POH ,also use a little higher fuel burn to compensate for climb out . I put the higher fuel number in so I don't run out of fuel.
 
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