Ok, so then basically what I make out from what you're saying is that as the dynamic pressure remains constant if we keep a same airspeed as we climb, the anemometer senses the change in density (reduction) and so it is the anemometer that calculates the increased v and displays it in knots on the Airspeed indicator right?

I have one more question which is different to this:

An aeroplane moves from Point A with coordinates 60ºN/030ºW. It then moves the following distances:
1. 3600 Nm South
2. 3600 Nm East
3. 3600 Nm North
4. 3600 Nm West

What is its final position?

I keep getting 60ºN/090ºW but books says 60ºN/060ºW.
Can you please help me with this?

Thanks a lot.

Initial Position 60N 030W
3600 NM going south equals 60 deg (1 NM=60 deg on a meridian which is a great circle)
second position 000 030W
3600 NM going east equals 60 deg (1 NM= 60 deg on the equator which is a great circle)
third position 000 030E
3600 NM going north equals 60 deg (1 NM=60 deg on a meridian which is a great circle)
forth position 60N 030E
3600 NM going west equals this time 120 deg
(e=G cosL=3600 that means g=e/cosL=3600/cos60=7200'=120deg)
Final position is 60N 090W

I guess the answer on the book is not correct.

Thanks, I had a strong feeling the book was wrong because up to the second last question it had the same working outs like you.

"Ok, so then basically what I make out from what you're saying is that as the dynamic pressure remains constant if we keep a same airspeed as we climb, the anemometer senses the change in density (reduction) and so it is the anemometer that calculates the increased v and displays it in knots on the Airspeed indicator right?"

No.

The Airspeed Indicator has no means of measuring air density.

It simply measures the dynamic pressure and gives you an indicated airspeed that is determined by that pressure.

If the air density is equal to that at ISA msl, then the indicated airspeed will equal TAS (ignoring instrument errors and pressure sensing errors).

But if the density is less than ISA msl, then the indicated airspeed will be less than TAS.

If the density is higher than ISA msl then the indicated airspeed will be more than TAS.

But the Aispeed Indicator has no way of measuring density or TAS, and it does not actually indicate TAS.

Ok...but then let's suppose a situation. We apply a certain amount of power to the throttle and we're climbing at 250 knots. To those 250 knots there is a corresponding dynamic pressure. As we increase in altitude, pressure decreases which means that the dynamic pressure would also decrease which means our IAS would tend to decrease as we increase in altitude.

I think this idea what I have is wrong so can you please tell me where I'm going wrong as this is getting me confused now.

That bit could be correct. What is missing from your example is how you are flying, what is your target? It is normal to climb at a fixed IAS at lower levels, this would mean that, as air density decreases, your TAS would increase. If, however, you were somehow holding a fixed True Air Speed then, yes, the IAS would decrease as air density decreases. The problem is that it is quite hard to hold a fixed TAS, there is no TAS meter in the cockpit.

"To those 250 knots there is a corresponding dynamic pressure. As we increase in altitude, pressure decreases which means that the dynamic pressure would also decrease which means our IAS would tend to decrease as we increase in altitude."

As Alex has said, that could be true.

Let's imagine that we have a very unusual aeroplane that is fitted with an EASmeter, a CASmeter, a TASmeter and a MACHmeter.

With these instruments we could choose to fly at a constant value of any of these speeds.

Lets imagine we climb at constant EAS in the ISA below the tropopause.

When doing this we would see

Constant reading on the EASmeter.
Increasing reading on the CASmeter.
Increasing reading on the TASmeter.
Increasing reading on the MACHmeter.

Now if we repeat the climb, but at constant CAS we would see.

Decreasing reading on the EASmeter.
Constant reading on the CASmeter.
Increasing reading on the TASmeter.
Increasing reading on the MACHmeter.

If we now repeat the climb, but at constant TAS we would see.

Decreasing reading on the EASmeter.
Decreasing reading on the CASmeter.
Constant reading on the TASmeter.
Increasing reading on the MACHmeter.

This is the situation which you appear to have been describing in your most recent post.

And if we repeat the climb, but at constant MACH we would see.

Decreasing reading on the EASmeter.
Decreasing reading on the CASmeter.
Decreasing reading on the TASmeter.
Constant reading on the MACHmeter.

The relationships between EAS, CAS and TAS are determined by air density, which is determined primarily by static pressure.

The relationship between TAS and MACH is determined by air temperature.

I understand what you both have said, sorry to bother you a lot, but my question was related to the anemometer in an aeroplane that measures the IAS. As you said previously, Keith. Williams., the anemometer is a differential pressure gauge which measures the difference between the total pressure and static pressure to get the dinamic pressure in order to calculate the IAS. Now what I want to clarify is that if we, for instance, takeoff and we'd set 250 knots airspeed straight away and not touch the throttle, the anemometer would eventually detect lower and lower pressure as we increase in altitude and this lower pressure would mean that this anemometer would show a lower IAS at a higher altitude, right?

If you mean a constant TAS of 250 kts then the IAS will decrease as you climb.

If we go back to the dynamic pressure equation we can see why.

Dynamic pressure = 1/2 Rho Vsquared

Rho is the air density and V is the TAS.

So in a constant 250 Kt TAS climb dynamic pressure = 1/2 Rho 250squared.

As altitude increases, the static pressure decreases. This causes the air to expand, so its density, Rho decreases.

If we hold TAS constant while we climb, then the 250squared stays constant while the Rho decreases. So the dynamic pressure must decrease.

The ASI simply measures dynamic pressure, so its indication will decrease.

So if we climb at a constant 250 kts TAS the indicated airspeed will decrease.

Ok, that answers my question. Thanks Keith. Williams. and Alex Whittingham.

There is another reason, though. If you set thrust and attitude for 250KT IAS at sea level and maintained attitude in the climb while not touching the thrust levers the IAS would fall not only because of the IAS/TAS relationship but mainly because thrust falls with increasing altitude. To hold a constant TAS you would actually have to lower the nose from the original attitude.

Well for a start I do get help from my instructors at my school and when I have any doubts I do ask them but when I go back and read the actual books, which go into quite a depth, I have more questions and I find that here on Pprune I get quick answers rather than waiting for the next day or maybe week until the instructor turns up when I have a class for that subject (I don't have 1 instructor for all subjects).

pilotmike, is there a problem to me asking questions here on Pprune regarding ATPL Theory? All the people that have helped me here do it on their own will, and I appreciate that of them, not thinking of giving "free tuitions" like you said.

Ok, I see your point towards my school's "reputation" but if I have a question, I don't think about the possibility of it being "stupid" or "relatively simple" and like I said I don't wait until the next day or week to ask a teacher and consider posting it on Pprune.
About the posts I make, I am not seeking a high post count (like it affects anything!) and I'm repeating myself in saying that people help me on their own will and I'm sure the "goodwill" won't get used up in 1 week as I'm not taking the piss of anything.

One of my instructors is fond of saying 'the only stupid question is the one you don't ask'. Its not a good thing, particularly in class, to be intimidated into not asking questions.

There are other forums which might be more appropriate, though. PPRuNe has a 'questions' forum for the simple stuff and 'tech log' for the difficult and debatable. Most of the larger groundschools also have Q&A forums although the instructors there do sometimes get a bit shirty when asked to sort out misunderstandings primarily caused by bad tuition at other schools. Maybe the 'questions' forum would be a good place next time?

Ah well, thanks for pointing out this "questions" forum, didn't know there was one (thought this was the place to put it as it was "Professional Pilot Training (includes ground studies)"). I'll put my questions there next time.

Don't get me wrong, we're always pleased to help, Keith in particular. If you search for posts by Keith.Williams you'll find he's a fountain of knowledge.

Yeah, well I appreciate that from both of you. I suppose you guys answer in the "questions" forum too right?

After having had just over two months of ATPL Theory I'm starting to wonder what is the best way for studying for the exams. How have most of you people got around it? I'm not sure if making notes is the best way because when I look at my book of Airplane Systems (1000 pages) I just don't see whether I would get the time to read all the notes I would have to make. The same goes for some other books like Meteorology. Alternatively how would memorizing the questions database be?

Can you people put in some feedback on how you guys got around the exams and what is the best/recommended way for studying for these exams?

Thanks.

I'm selling my Bristol.gs Books, DVD, ... (reason: Change to integrated training)
Bristol approved the sale to another student and will provide the brushup course.

Price can be discussed.

Please pm if interested.

jepessen atpl test prep cd
 

hi there
i have the 15 jepessen atpl manuals and i understand i should have received with them a test prep cd with 2700 revision style questions
does anyone have a copy of this they are willing to part with
kind regards:p