Filling out a flight plan?

Question

On the flight plan form, block 4 asks for the true airspeed in knots. How do you know what the true airspeed will be? Is there a general speed that is used for each type of plane, or is there a calcualation?

Answer 1

Most pilots enter an estimate or a typical figure of what airspeed can be expected from the airplane you are flying.  If you use the TAS tables in the Pilot's Operating Handbook, you will be covered.

Answer 2

Stated by "Comair":

Again everyone, including avio is wrong.

There is NO estimating in aviation.

There's a calculation. Here's a example. We will fly at 280 KIAS at FL330 - what will our KTAS likely be?

TAS increases by roughly 2% per 1000' of altitude gain.

280 x 1.66 = 465 KTAS

Or you can use a E6b flight computer

    * 20 hours ago

My Response:

Comair, you are far less than authentic. TAS does not vary according to winds (talking flight plan TAS here, not talking wind shear on approach or whatever) and, yes, pilots do estimate TAS. Even when forecast temps are used, it's still an estimate.  I have estimated TAS for varying aircraft at given speeds ranging from 390 to 460 knots (e.g., 390k, 420k, 440k, 450k, for 4 different aircraft I have flown) and have always been within acceptable parameters for flight planning purposes. And, by the way, all other things being constant, your TAS (or Mach number; flight plans with FAA are in knots) will increase as fuel is burned, for a given power setting. So, looking at one chart or performing one calculation is good for that weight, temp, power setting, etc. only.  In other words, a snapshot of sorts, particularly for long flights. The "estimated" or even "average" nature of the flight plan TAS is reflected by the allowable variation in TAS before ATC should be notified of the deviation from flight plan TAS. Whether you power back and keep the same TAS as fuel is burned has more to do with fuel burn and range issues. Also: TAS does not "increase by 2% per 1,000 feet".  You'll reach a point in a jet at which TAS will start to decrease with altitude, but fuel economy will increase.  The 2% figure you are mentioning relates to the difference between IAS (which decreases with altitude) and TAS (which increases with altitude, to a point, and then drops off, in favor of fuel economy.) But, if you were not comparing IAS to TAS, the statement that TAS increases by 2% per 1,000 feet would be incorrect. In fact, in some temperature environments, that 2% figure could be way off. Guess what:It's an ETSIMATE!! An AVERAGE!! The irony is notable: In criticizing others for correctly stating that estimates

and averages are used, you have proposed an estimate, an average (which can vary significantly from reality on any given day in a given actual temperature envornment)---your "2% per thousand feet".  You might want to speak to the Comair dispatchers: you'll find that they don't use the 2% rule. The use  info from the charts others have mentioned (incorporated into software) and from forecast (i.e., estimated) temps and for a specific or average weight, etc.

Answer 3

Check another question with very good answer with calculations

The question was about How can I calculate the ground speed in a specific height if I have only the mach number (and flight level)?

http://answers.yahoo.com/question/index;...

Answer 4

Gotta laugh at comairs answer! There's no estimating in aviation, yet you use the 2% per thousand ft RULE OF THUMB?!

Sorry but avio does have it right. You'll consult the cruise performance charts to determine what TAS will suit your purpose/mission. The charts will give you your performance in TAS. You just enter the chart or graph with the conditions that exist and and whatever TAS that you want, and you'll be able to find what power setting will give you what you need. Even then, those numbers are fairly conservative. You can do better, so it is ultimately an estimate. TAS isn't affected by the wind either.

So what TAS do you want to fly today?

Answer 5

Look carefully at the performance information on the aircraft flight manual or a pilot's operating handbook.

In it you will find the TAS for various altitudes and power settings.

Just use the number for whatever altitude/power setting combination you plan on using for the flight.

Answer 6

For commercial aircraft, this will be figured out by a computer that makes up flight plans and tailors it for optimum performance. The captain OK's it, and signs off on it, along with a dispatcher.

Regards,

Dan