Ground School Exam Questions & Question Banks
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thanks once again guys, very much appreciated. I can see now that if id used 1.8 instead of the 1.5 that is EVERYWHERE in my manuals (its even in Trevor Thom for gawds sake!) then id have got the answer. will be more wary in future.
take care and fly safe.
take care and fly safe.
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The SALR is not a fixed number. Its value depends on the amount of water vapour in the air. Where the air is very dry it gets near to the DALR value. We all used to use the approximate temperate zone sea level value of 1.5, but the JAA changed the exam value to 1.8.
I don't know why they changed, but as it is an approximation the choice is not critical as long as we all use the same value.
Dick W
I don't know why they changed, but as it is an approximation the choice is not critical as long as we all use the same value.
Dick W
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Send Clowns, I think your temperature correction is wrong. It's not allowed to correct the elevation of your obstacle.
You should only correct for 1000feet, which gives us 72feet and thus 3072feet.
I stand to be corrected.
You should only correct for 1000feet, which gives us 72feet and thus 3072feet.
I stand to be corrected.
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Correct
To be very accurate it's 3258ft
4x19x3.405=258. You need to have a true altitude of 3000ft so, your indicated on QNH needs to be 3258ft.
When cold, True is less than Indicated.
I don't stand to be corrected.
;-)
4x19x3.405=258. You need to have a true altitude of 3000ft so, your indicated on QNH needs to be 3258ft.
When cold, True is less than Indicated.
I don't stand to be corrected.
;-)
Last edited by pugzi; 28th Feb 2005 at 07:56.
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The Regional QNH gives a lowest forecast QNH for a specified area. It is, therefore, impossible to accurately calculate an altitude above a specific obstacle; the answer above will give at least 1000' clearance, but probably more (just in case none of the exam answers fit).
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Just flicking through and came across this interesting question.Would someone mind breaking it up to explain the how the answer was achieved,as there are three possible outcomes shown? Just interested the method of working it out 
Thanks!
Thanks!
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Not an easy task, but we try to please
I've been going on about pictures for ages when it comes to these questions, so I'm gonna make you draw a picture.
Draw a horizontal line and label it "QNH sea level 998hpa"
Draw another above it and label that, "height of obstacle". Label the distance between these two lines as 2000ft.
Draw another line above the "height of obstacle" line and label the distance from the "height of abstacle" line to this new line as 1000ft.
Your true distance must be 3000ft above the sea for you to clear the obstacle by 1000ft. This is obvious to see. The ditance from the bottom line, to the top line.
What we need to work out is the indicated distance (why they are different is gonna take an essay, or 2 secs with an instructor)
Use this formulae.
For every 1°C ISA deviation your altimeter will be in error from the true altitude by 4ft in every 1000ft of pressure altitude.
Lets work out pressure altitude (the height above 1013.2hpa) so that we can start to use this formulae.
Draw another line under the "QNH sea level 998" line and label this as "1013.2hpa". The distance between this line and the QNH line is 405ft (27ft x 15 hpa). So the pressure altitude of an aircraft that needs to clear the obstacle is 3405ft. Please don't look at the diagram again cos it'll start to mess with your head. We have all we need now from it.
OK, we have 19°C ISA deviation in the example and we have 3.405 thousands of feet pressure altitude. Now we can use that formulae.
So, 19°C deviation x 4ft gives an error per 1000ft of 76ft. But, we have 3.405 thousands of feet.
So, 76 x 3.405 gives a total error of 258ft.
When it's cold the true altitude (in our case 3000ft) is always less than the indicated altitude, so indicated altitude on QNH must be 3000ft plus 258ft.
Hope this helps.
I did try
Steve Francis
Draw a horizontal line and label it "QNH sea level 998hpa"
Draw another above it and label that, "height of obstacle". Label the distance between these two lines as 2000ft.
Draw another line above the "height of obstacle" line and label the distance from the "height of abstacle" line to this new line as 1000ft.
Your true distance must be 3000ft above the sea for you to clear the obstacle by 1000ft. This is obvious to see. The ditance from the bottom line, to the top line.
What we need to work out is the indicated distance (why they are different is gonna take an essay, or 2 secs with an instructor)
Use this formulae.
For every 1°C ISA deviation your altimeter will be in error from the true altitude by 4ft in every 1000ft of pressure altitude.
Lets work out pressure altitude (the height above 1013.2hpa) so that we can start to use this formulae.
Draw another line under the "QNH sea level 998" line and label this as "1013.2hpa". The distance between this line and the QNH line is 405ft (27ft x 15 hpa). So the pressure altitude of an aircraft that needs to clear the obstacle is 3405ft. Please don't look at the diagram again cos it'll start to mess with your head. We have all we need now from it.
OK, we have 19°C ISA deviation in the example and we have 3.405 thousands of feet pressure altitude. Now we can use that formulae.
So, 19°C deviation x 4ft gives an error per 1000ft of 76ft. But, we have 3.405 thousands of feet.
So, 76 x 3.405 gives a total error of 258ft.
When it's cold the true altitude (in our case 3000ft) is always less than the indicated altitude, so indicated altitude on QNH must be 3000ft plus 258ft.
Hope this helps.
I did try
Steve Francis
Last edited by PGT; 1st Mar 2005 at 08:47.
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Errmmmm, PGT (and pugzi), you must only correct for the depth of indicated altitude, not for the pressure altitude, so that's 3,000 feet not 3,405. You are correcting for 405 feet of sea! The PA is only used for finding the temperature deviation.
ISA is closer to 8° than 9° at 3400 feet! ISA deviation is -18°. Sorry to be pedantic, but to avoid confusion. I suspect you got your two altitudes the wrong way round in the calculation, as that would account for both errors.
Subsidence
If this was using a real QNH measured at the top of the obstacle you would be right. As it is this question uses the horrible (and incorrect) term "Regional QNH". Regional pressure setting is not a QNH at all, nor based on them, hence the military do not allow their pilots to use the term "Regional QNH"! It is calculated from QFFs*, which are corrected for off-ISA temperature. It is also probably calculated from measurements well below the elevation of the obstruction, so even using a QNH you must account for temperature between where the QNH is measured and the aircraft, not the obstruction height and the aircraft.
Hope this clarifies!
Send Clowns
*Regional pressure setting is the lowest QFF forecast in the region over the following 2 hours, and is valid for 1 hour.
ISA is closer to 8° than 9° at 3400 feet! ISA deviation is -18°. Sorry to be pedantic, but to avoid confusion. I suspect you got your two altitudes the wrong way round in the calculation, as that would account for both errors.
Subsidence
If this was using a real QNH measured at the top of the obstacle you would be right. As it is this question uses the horrible (and incorrect) term "Regional QNH". Regional pressure setting is not a QNH at all, nor based on them, hence the military do not allow their pilots to use the term "Regional QNH"! It is calculated from QFFs*, which are corrected for off-ISA temperature. It is also probably calculated from measurements well below the elevation of the obstruction, so even using a QNH you must account for temperature between where the QNH is measured and the aircraft, not the obstruction height and the aircraft.
Hope this clarifies!
Send Clowns
*Regional pressure setting is the lowest QFF forecast in the region over the following 2 hours, and is valid for 1 hour.
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Kinda
"you must only correct for the depth of indicated altitude" i kinda agree, but we dont know the indicated altitude on QNH, thats what the question is asking for. The only indicated altitude we can know is PA. So we have to work with pressure altitude. Well thats my opinion.
Anyway, it s a bad question, but more importantly I think we lost the student though.
;-)
Anyway, it s a bad question, but more importantly I think we lost the student though.
;-)
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Sorry to be a bit blunt here, but why don't you approach your training providers with these questions?
I have done a search through your previous posts asking for help, and it appears you have been doing these studies for quite a while now!!!
Surely your school instructors are the most appropriate people to ask.
I have done a search through your previous posts asking for help, and it appears you have been doing these studies for quite a while now!!!
Surely your school instructors are the most appropriate people to ask.
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PGT
I suppose you have a point, in that we are trying to find indicated altitude from true and this calculation actually corrects indicated altitude to true, and agree it's a bad question and that he therefore may not be able to follow. However the only way more accurate than what I am suggesting is to use iteration, using the new calculation of indicated altitude to recalculate the correction.
I don't think pressure altitude is a good way of looking at this, because it has a weaker relationship with indicated altitude than true altitude does, QNH having a greater effect than temperature change. If the PA had been, for example 2,500 feet instead of 3,500 feet this would have been even further out than any of the answers yet suggested, and in the low sense.
How about 18 x 4 x 3.233 = 233 feet as the correction, giving 3,233 feet as the answer from the formula to the nearest foot!
DA
Well PGT and I are training providers, so should be as good as any, and in my humble opinion we are better than most
!
I suppose you have a point, in that we are trying to find indicated altitude from true and this calculation actually corrects indicated altitude to true, and agree it's a bad question and that he therefore may not be able to follow. However the only way more accurate than what I am suggesting is to use iteration, using the new calculation of indicated altitude to recalculate the correction.
I don't think pressure altitude is a good way of looking at this, because it has a weaker relationship with indicated altitude than true altitude does, QNH having a greater effect than temperature change. If the PA had been, for example 2,500 feet instead of 3,500 feet this would have been even further out than any of the answers yet suggested, and in the low sense.
How about 18 x 4 x 3.233 = 233 feet as the correction, giving 3,233 feet as the answer from the formula to the nearest foot!
DA
Well PGT and I are training providers, so should be as good as any, and in my humble opinion we are better than most
!
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Calculations of altimeter error due to temperature deviations from ISA, are, as has been made abundantly clear(?), full of approximations and assumptions. First off, the "rule of thumb" is itself an approximation. Secondly, the appropriate CAA document uses (pace Send Clowns) the words "latest forecast QNH (Regional Pressure Setting) for each hour". Of course, this is a QNH datumed at msl, so ought to be the same as the QFF, except that a QFF is calculated differently, on the assumption that the air mass is isothermal at station temperature all the way down, or up, to be pedantic, to msl, and may be different from an amsl QNH.
For the JAA exams we assume that if we are flying on the Regional Pressure Setting we calculate temperature corrections on the height amsl that we want to achieve. For a 3000ft obstacle, which may or may not be solid, with a 1000ft clearance, we calculate the error over 4000ft. Of course, as Send Clowns points out, that gives a new number for indicated height, so for perfect accuracy we might re-calculate on this figure, and so on ad infinitum. However, there is no point in doing this, for the assumption we made in the Rule of Thumb that ISA deviation was the same at all heights may have already introduced significantly larger errors.
And there is the perfectly valid point that if the first 3000ft is filled with rock, the actual conditions may be sigificantly different from the case of overflying a 3000ft TV mast.
So let us apply the KISS principle. Use the given Rule of Thumb with all its approximations and base your corrections on height amsl if the Regional Pressure Setting is in use, whatever the ground in between.
In real life, the procedure for calculating safety altitude introduces enough factoring to take care of the small errors.
Dick W
For the JAA exams we assume that if we are flying on the Regional Pressure Setting we calculate temperature corrections on the height amsl that we want to achieve. For a 3000ft obstacle, which may or may not be solid, with a 1000ft clearance, we calculate the error over 4000ft. Of course, as Send Clowns points out, that gives a new number for indicated height, so for perfect accuracy we might re-calculate on this figure, and so on ad infinitum. However, there is no point in doing this, for the assumption we made in the Rule of Thumb that ISA deviation was the same at all heights may have already introduced significantly larger errors.
And there is the perfectly valid point that if the first 3000ft is filled with rock, the actual conditions may be sigificantly different from the case of overflying a 3000ft TV mast.
So let us apply the KISS principle. Use the given Rule of Thumb with all its approximations and base your corrections on height amsl if the Regional Pressure Setting is in use, whatever the ground in between.
In real life, the procedure for calculating safety altitude introduces enough factoring to take care of the small errors.
Dick W
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Ah, I learn from the RAF and RN, and they tend to ignore what the CAA says when they think they know better!
Agree with all you say about approximations, Dick, and apologise for students for getting into too much detail. However I am (sadly) quite interested in the intellectual challenge of solving problems like this in discussion with the other instructors here. We have gone beyond what a student must understand!
Agree with all you say about approximations, Dick, and apologise for students for getting into too much detail. However I am (sadly) quite interested in the intellectual challenge of solving problems like this in discussion with the other instructors here. We have gone beyond what a student must understand!
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Ground School Exam Questions & Question Banks
Hi people, this may seem like a stupid question to post but could somebody just take a look at it and tell me what you think is the correct answer:
The primary flying controls are:
a. the roll and pitch controls
b. the flaps, ailerons, and elevators
c. the ailerons and rudder
d. those which provide control about the primary axes
It comes from POF.
Thanks in advance
The primary flying controls are:
a. the roll and pitch controls
b. the flaps, ailerons, and elevators
c. the ailerons and rudder
d. those which provide control about the primary axes
It comes from POF.
Thanks in advance
Guest
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Hmmm. I would have throught primary must mean under direct control of the pilot (i.e. not A/P) and directly affects the attitude of the a/c. D is interesting because of the word "about". I would have throught that the throttle is a primary control along the longitudinal axis, as that is not mentioned then it is strictly incorrect. I wouldn't consider flaps a primary control because they are intended to change the flight characteristic for very specific reasons. Faced with Roll and Pitch or Ailerons and Rudder I would say that Rudder is least important so I would answer A or D. Being somewhat concerned that I am reading too much into D I may settle on D after flipping a coin.
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By definition the primary flying controls are those which control rotations about the primary (longitudinal, lateral and vertical) axes.
Options a and c are true but incomplete. Option b is untrue because it includes the flaps. Only option d is correct.
Options a and c are true but incomplete. Option b is untrue because it includes the flaps. Only option d is correct.
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Okay....very interesting. First of all thanks a million for all the quick responses.
Well this question came up in a recent assessment and I chose D, but I was told by my school that it was wrong, they informed me that answer C was the "most" correct answer. The reason? They said that answer D could include trim tabs, balance tabs, servo tabs, etc.
Now I dont know whether this is a question they made up or is an actual feedback question, what I do know is that if this was a feedback question and the JAA said that answer C was correct I would be very
Well this question came up in a recent assessment and I chose D, but I was told by my school that it was wrong, they informed me that answer C was the "most" correct answer. The reason? They said that answer D could include trim tabs, balance tabs, servo tabs, etc.
Now I dont know whether this is a question they made up or is an actual feedback question, what I do know is that if this was a feedback question and the JAA said that answer C was correct I would be very
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It makes sense now you mention it Fergal. The beep beeeeeep beep. How beep beeeeeeeep beep beeep beeeeeep?
I just asked my mate who has never flown a plane or even knew what an ATPL exam is. He immediately logically broke the problem down and nailed the correct answer
I just asked my mate who has never flown a plane or even knew what an ATPL exam is. He immediately logically broke the problem down and nailed the correct answer
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If the question had asked what ailerons and rudder are then the answer would have been primary flying controls. But saying that the ailerons and rudder are primary flying controls is not the same as saying that primary flying controls are the ailerons and rudder.
The question asked what primary flying controls are. They are by definition, those flying controls which control rotations of an aircraft about its three axes.
This does not mean that everything which is able to control motions about the three axes must be a primary flying control. In most aircraft with underslung engines, any changes in thrust produce pitching motions. But this does not make the throttle a primary flying control.
Trim tabs, balance tabs, and servo tabs are all forms of aerodynamic balance. Their function is to control or modify the control hinge moments. These tabs are not intended to control the rotation of the aircraft about its three axes. They are intended to assist the pilot to move the primary flying controls to do so.
The question asked what primary flying controls are. They are by definition, those flying controls which control rotations of an aircraft about its three axes.
This does not mean that everything which is able to control motions about the three axes must be a primary flying control. In most aircraft with underslung engines, any changes in thrust produce pitching motions. But this does not make the throttle a primary flying control.
Trim tabs, balance tabs, and servo tabs are all forms of aerodynamic balance. Their function is to control or modify the control hinge moments. These tabs are not intended to control the rotation of the aircraft about its three axes. They are intended to assist the pilot to move the primary flying controls to do so.