Weight, Wind
 

Starting my posting career here with homework help, I guess that is as expected. Im currently doing the performance portion of my ATPL(A) and I've been trying to wrap my head around a few concepts, I'm a fairly low time pilot (1000TT Light AC with about 850 as an instructor) with training from the US converting my licenses in Norway.

As Ive seen, people are not too fond of outright "what is the answer to my question"-threads, so I'll try first, then see how far off I am. Unfortunately, the Oxford book is pretty short on information about this subject, not really giving me what I'm looking for. If there are other databases where I can soak up information like this, tips are appreciated.



An airplane is descending with a constant IAS and zero thrust. What happens to the descent gradient when the OAT increases?

Pretty lost at this one. Safe to say, if this was a climb the answer would be obvious, the low air density would result in worse climb performance. Is it safe to assume that the opposite is true for descent gradient? That the lower air density would result in less parasite drag and therefore allowing me to keep a lower descent gradient in an engine out situation?



An airplane is descending with a constant IAS and zero thrust. What happens to the descent gradient when the airplane reaches a lower altitude?

As my only answer to the last question was as mentioned, I would now assume that due to the air density increasing as we reach lower altitudes, parasite drag would again increase and force a higher descent gradient. From reading about configuration and its effects, it seems that more drag will increase the gradient. But I also want to clarify that this is not due to the pitch down moment often associated with extending flaps and gear.




An airplane is descending with a constant IAS. What happens to the descent path gradient when tailwind is increasing?

I think I got this one, but we'll bring it in anyway, since gradient is directly related to groundspeed, I would assume that a higher ground speed would increase my gradient. Am I underthinking this?



Hopefully this doesnt annoy anyone, as I have atleast tried to come up with a homemade solution to this, feel free to flame my incompetence! (Starting to wonder if I'll even survive the ATPL(A))

EDIT: Thread title is messed up, unfortunately I cant find a way to edit it

Hey odd ball... and the below is just my opinion. You might want to double check it with the textbooks, as i might make mistakes too, that you have already have the answers are in there.

1)An airplane is descending with a constant IAS and zero thrust. What happens to the descent gradient when the OAT increases?

Please revisit the lift equation.
Constant IAS - constant Q factor.
OAT increase - increase/decrease what variable of the lift equations

what needs to be compensated to maintain the same Q factor.

FYI you might want to revisit the chapter on drag, if you are maintaining the same IAS drag remains the same...

it should bring you to the conclusion that the gradient increases.

2) An airplane is descending with a constant IAS and zero thrust. What happens to the descent gradient when the airplane reaches a lower altitude?

in this case the steps to analysis this is the same as the first question, however you do not compare/consider OAT as a factor at a instantaneous point. you compare the conditions at different altitude.

it should bring you to the conclusion that the gradient decreases, as with a down drift.

3)An airplane is descending with a constant IAS. What happens to the descent path gradient when tailwind is increasing?

I believe you want to revisit part in the book defining gradient (air/ground). air gradient is independent of wind.

tailwind decreases the ground gradient and and actual flight path angle will reduce accordingly.

Oxygen requirements - I don't get it!
 

I think I'm being stupid.
Question concerns supply requirements for supplemental oxygen for passengers in a pressurised aeroplane.
The book says:
100% of passengers: entire flight time when cabin altitude exceeds 15,000 feet but in no case less than 10 minutes.
30% of passengers: entire flight time when cabin altitude exceeds 14,000 feet but does not exceed 15,000 feet
10% of passengers: entire flight time when the cabin altitude exceeds 10,000 feet but does not exceed 14,000 feet after the first 30 minutes at this altitude.
OK so after a pressurisation failure and cabin altitude becomes 14,500 feet who decides which 30% of passengers get the oxygen and which don't?
And how does the operator know in advance how much oxygen to supply if they can't know in advance what cabin altitude the failure will cause?
I think I'm missing something very simple here

I'll have a go at this:
An airplane is descending with a constant IAS and zero thrust. What happens to the descent gradient when the OAT increases?

No change in descent gradient.
Descent gradient (much like the climb gradient) is a function of excess drag vs weight (ie. (D-T)/W ). Since thrust is zero for our question, we can use D/W. Neither changes so the air gradient will remain the same.

Hotter (or colder) air does not imply less drag if we are flying at constant IAS. Assuming no compressiblity, const IAS implies constant EAS and constant q. Weight is constant, Lift is constant, density will increase(or decrease), but speed changes to adjust for it (TAS will therefore change), Cl remains constant (as in the angle of attack is constant).If Cl (and angle of attack remains the same) so wil Cd and Drag.

I am half-way through my ATPL (H) exams, so far so good. Are average marks for each subject available in the public domain? It would be interesting to see how I measure up - it is a competition after all.

Basic ATPL QFE. question
 

I am not struggling with this and understand the differences etc, but just trying to make sense of an answer without the workings given.

According to the Met Handbook.... '1hPa change per 27ft of pressure change down to sea level"

The question goes something along the lines of

"If the QNH at Coventry (200 meters above sea level) is 1025 hPa, wha is the approximate QFE?"

My working is:

200/27 = 7.4 - round down to 7.

1025 - 7 = 1018 - A minus as the QFE would be lower than the QNH.

My answer QFE = 1018.

The answer however is 1000 HpA .

Just wondered if the mathematical derivation of this is using the above rule of "1hpa pressure change per 27ft"..

Not sure how this works out at 1000 HPa.

Hello,

Have you considered the conversion between feet and metres?

Basic ATPL QFE. question
 

You should convert 200 meters to feet and then do the calculations.

Ok I am with you...

200 meters = 656 feet.

656/27 = 24.296 - Call it 24.

1025 - 24 = 1001 hPa QFE.

So approx 1000 hPa as stated in the handbook.

Cheers.

...........RTFQ

Not heard that before...

Google it!

You will a lot during study..

Read The :mad: Question.

Also, just as important is RTFA. I think you can now work that one out. :ok:

Here's how I did it:
1hPa = 27ft = 8m

200 : 8 = 25

1025hPa - 25 = 1000

V Speeds - Help
 

Hello everybody.

If anybody could try and help me with the answers for some "advanced" questions I have come across over the years it would be greatly appreciated

1. Given that:
VEF= Critical engine failure speed
VMCG= Ground minimum control speed
VMCA= Air minimum control speed
VMU= Minimum unstick speed
V1= Take-off decision speed
VR= Rotation speed
V2 min.= Minimum take-off safety speed
The correct formula is:

a) VMCG<=VEF < V1
b) 1.05 VMCA<= VEF<= V1
c) 1.05 VMCG< VEF<= VR
d) V2min<= VEF<= VMU

2. The induced drag of an aeroplane at constant gross weight and altitude is highest at

a) VSO (stalling speed in landing configuration)
b) VS1 (stalling speed in clean configuration)
c) VMO (maximum operating limit speed)
d) VA (design manoeuvring speed)

3. The stalling speed or the minimum steady flight speed at which the aeroplane is controllable in landing configuration is abbreviated as

a) VSO.
b) VS1.
c) VS.
d) VMC.

4. Which of the following speeds can be limited by the ’maximum tyre speed’?

a) Lift-off groundspeed.
b) Lift-off IAS.
c) Lift-off TAS.
d) Lift-off EAS.

5. During the flight preparation a pilot makes a mistake by selecting a V1 greater than that required. Which problem will occur when the engine fails at a speed immediately above the correct value of V1?

a) The stop distance required will exceed the stop distance available.
b) The one engine out take-off distance required may exceed the take-off distance available.
c) V2 may be too high so that climb performance decreases.
d) It may lead to over-rotation.

6. V1 has to be

a) equal to or higher than VMCG.
b) equal to or higher than VMCA.
c) higher than than VR.
d) equal to or higher than V2.

7. The take-off safety speed V2min for turbo-propeller powered aeroplanes with more than three engines may not be less than:


8. The speed V2 of a jet aeroplane must be greater than:

a) 1.2Vs.
b) 1.2VMCG.
c) 1.05VLOF.
d) 1.3V1.

9. As long as an aeroplane is in a positive climb

a) VX is always below VY.
b) VX is sometimes below and sometimes above VY depending on altitude.
c) VX is always above VY.
d) VY is always above VMO.


10. Higher gross mass at the same altitude decreases the gradient and the rate of climb whereas

a) VY and VX are increased.
b) VX is increased and VY is decreased.
c) VY and VX are not affected by a higher gross mass.
d) VY and VX are decreased.

11. Given a jet aircraft. Which order of increasing speeds in the performance diagram is correct?

a) Vs, Vx, Maximum range speed
b) Maximum endurance speed, Long range speed, Maximum range speed
c) Vs, Maximum range speed, Vx
d) Maximum endurance speed, Maximum range speed, Vx

12. Approaching in turbulent wind conditions requires a change in the landing reference speed (VREF):

a) Increasing VREF
b) Lowering VREF
c) Keeping same VREF because wind has no influence on IAS.
d) Increasing VREF and making a steeper glide path to avoid the use of spoilers.


13. What margin above the stall speed is provided by the landing reference speed VREF?

a) 1,30 VSO
b) 1,05 VSO
c) 1,10 VSO
d) VMCA x 1,2


14. Which of the following answers is true?

a) V1 is lower or equal to VR
b) V1 is higher VLOF
c) V1 is higher VR
d) V1 is lower VMCG


15. Which statement is correct?

a) VR must not be less than 1.05 VMCA and not less than V1.
b) VR must not be less than VMCA and not less than 1.05 V1.
c) VR must not be less than 1.1 VMCA and not less than V1.
d) VR must not be less than 1.05 VMCA and not less than 1.1 V1

16. Which of the following represents the minimum for V1?

a) VMCG
b) VLOF
c) VMU
d) VR


17. Which of the following represents the maximum value for V1 assuming max tyre speed and max brake energy speed are not limiting?

a) VR
b) VMCA
c) V2
d) VREF


18. The correct formula is: (Remark: "<=" means "equal to or lower")

a) VMCG<=VEF < V1
b) 1.05 VMC<= VEF<= V1
c) 1.05 VMCG< VEF<= VR
d) V2min<= VEF<= VMU


19. Regarding take-off, the take-off decision speed V1:

a) is the airspeed on the ground at which the pilot is assumed to have made a decision to continue or discontinue the take-off.
b) is always equal to VEF (Engine Failure speed).
c) is an airspeed at which the aeroplane is airborne but below 35 ft and the pilot is assumed to have made a decision to continue or discontinue the take-off .
d) is the airspeed of the aeroplane upon reaching 35 feet above the take-off surface.


20. Which of the following sequences of speed for a jet aeroplane is correct? (from low to high speeds)

a) Vs, maximum angle climb speed, maximum range speed.
b) Vs, maximum range speed, maximum angle climb speed
c) Maximum endurance speed, maximum range speed, maximum angle of climb speed.
d) Maximum endurance speed, long range speed, maximum range speed.


21. In accordance to CS 25 which of the following listed speeds are used for determination of V2min:

a) VSR, VMCA
b) VMCG, V2
c) VLOF, VMCA
d) V1, VR.

22. In certain conditions V2 can be limited by VCMA

a) Low take-off mass, large flap extension, low field elevation.
b) Low take-off mass, small flap extension, low field elevation.
c) High take-off mass, large flap extension, low field elevation.
d) High take-off mass, small flap extension, high field elevation.


23. The relationship of the reference landing speed (VREF) to the reference stalling speed in the landing configuration (VSRO) is that VREF may not be below:

a) 1.23VSRO
b) VSRO
c) 1.1 VSRO
d) 1.32 VSRO


24. V2 has to be equal to or higher than

a) 1.1 VMCA
b) 1.15 VMCG
c) 1.1 VSO
d) 1.15 VR.


25. The value of V1 has to be equal to or higher than:

a) VMCG
b) VMC
c) VR
d) V2



26. In accordance with JAR 25 the take-off safety speed V2min for turbo-propeller powered aeroplanes with more than three engines may not be less than:

a) 1.08 VSR
b) 1.2 VSR
c) 1.13 VSR
d) VSR

May I ask whether you are doing a formal ATPL course, Jay? it would take quite a bit to explain the answers to all 25 questions but this is pretty standard stuff, it should be in your course material.

Stall question from the Belgium exam
 

Hope this is the right section to post this.

This is a question from the Belgium exam

A possible cause for the auto recovery of an airplane after a stall is
a. The angle of incidence (AOI) of the wing is larger than the AOI of the stabilizer
b. The wing surface is bigger than the wing surface of the stabilizer.
c. The AOI of the wing is smaller than the AOI of the stabilizer.
d. The angle of attack (AOA) of the stabilizer is bigger than the AOA of the wing.

1. is the right answer but why? Is the question anyhow correct and can you generalise this question for every plane?

Hi Peter,

If the AOI of the main wing is greater than the AOI of the stabiliser, the wing will reach it's critical angle of attack and stall first as the stabiliser's angle of attack will be lower due to a lower AOI presented to the airflow.

As the wing stalls first, the aircraft will usually pitch nose down as the stabiliser is still producing lift for the reason given above. As the aircraft pitches down, the wing angle of attack is reduced and it unstalls.

That's my take anyway! :)

ATPL Exam workbooks
 

With reference to CAA ATPL exams - CAP's were withdrawn earlier in the year and replaced with workbooks for the exam. Does anyone have any info on the content of the workbooks provided?

i.e. Mass & Balance, does it include conversion factors, I take it the definitions of masses has been removed, What about the level of info for SEP. MEP and MRJT?

Which CAA ATPL exam are you referring to?

Mass and Balance CAA ATPL Exams

If you have access to Aviation Exam, they have a supplement document you can download, with all the pics used in the workbooks by the UK CAA.


I revised for a week using that site, walked out with 92 percent.

For CAAS(Singapore)

The work book would be similar to the cap but extremely brief. For my exams there were no load and trim sheets.

You need to be familiar with some aspect of flight planning tables e.g. the climb performance, time and fuel consumed tables (not the graph).

Other than that, if you are familiar with the formulas you should be fine.

Hi guys

Sat ATPL Mass and Balance this week, amongst others. Results are due tomorrow.

The workbook provided for M&B contains graphs and charts that some of the questions will ask you to determine an answer from.

E.g. 'Refer to figure 011 in the workbook. What are the forward and aft CG limits of an aircraft with a landing weight of 58,000KG.'

They do not contain conversions or useful information. However, on one question which asked you to calculate maximum allowed fuel load based on given BEM, variable and traffic loads, they provided the table of standard passenger weights.

Bear in mind this may not be the case for other questions asking you to calculate specific allowed mass.

FAA ATP CTP and written.
 

Just passed the FAA ATP writtens first go (84%) after a week of both Sporties Pilot Shop books and the Sheppard Air online ATP Multi course.

The exam was a joke as I did not get one complex flight planning question, just easy graphical and W&B ones. The only calculation I got wrong was coverting an RVR of 5,000 ft to US miles. My calculator only did feet to NM, not US jobs!

If you have to suffer the FAA ATP writtens (The CAE CTP course was easy, although they are rather expensive), make sure you gen up on all the factors and definitions relating to CRM, as some of the questions seem to have 2 correct answers. It might well be turning into a real tough exam for the none native English drivers.

I'd only seen about half of the questions before, so it appears the FAA are trying to stop folks passing who just remember the answers.

Hi Portvale,

Yes, this would stump me. It is true (although rather obvious) that there can only be one sunrise and sunset each day, which is what the preamble to the question says.

The times of sunrise and sunset are given for a range of latitudes in Local Mean Time (LMT) for a particular day. Thus they are correct for all longitudes as LMT, but will need to have the time converted to UTC and possibly Standard Time depending on requirements.

Answer (b) is possibly true if 'these data are accurate only for places on the Greenwich meridian' actually means 'these data are accurate when (incorrectly) read as UTC times only for places on the Greenwich meridian' which is a bit of a stretch involving either a very badly written answer or a serious lack of understanding of LMT and UTC by the examiner.

As the times are LMT they are enough to be used for all longitudes with appropriate corrections applied, and the inference is that they are used to calculate light conditions, (c) is correct.

The sunrise and sunset times are only correct at mean sea level, and adjustment for altitude can be made, (d) is correct.

My money is on answer (a), but for the shabbiness of answer (b) whoever wrote this question should be flogged. Where is it from, please?

On reflection, the LMT times of sunrise and sunset will change from day to day, and therefore with the rotation of the earth. The LMT of sunrise at a particular latitude and 179deg59'W might be read from the almanac as 0600 LMT on the 5th March, for instance (made up numbers), whereas the LMT of sunrise from the tables for the next day at the same latitude and 179deg59E (only a few miles away) might show as 0605. Clearly they cannot both be correct, and in fact neither is, because the tables show LMT of sunrise and sunset at greenwich on the assumption that the difference for up to 12 hours equivalent of longitude is not wildly significant. That might be a better reason why (b) is true and avoids me slandering the examiner.

If you look in the full version of the Air Almanac in the explanations it says :-

in note 2 - that further correction graphs and tables are to be used to correct for the height of the observer. Option D true

in note 4 - sunrise, sunset & twilight are for the Greenwich meridian and it goes on to state there is no significant error in converting to LMT (other than using longitude arc to time). Options B & C true.

So on that A is correct, however I agree not a good question.

Can someone help me with this question
 

Can someone help me with this question

A pilot wishes to turn left on to a northerly heading with 10 degree bank at a latitude of 50 degree north. using a direct reading compass, in order to achieve this he must stop the turn to an approx heading of

a) 030 degree
b) 355 degree
c) 330 degree
d) 015 degree


A pilot wishes to turn right on to a northerly heading with 20 degree bank at a latitude of 40 degree north. using a direct reading compass, in order to achieve this he must stop the turn to an approx heading of

a) 030 degree
b) 350 degree
c) 330 degree
d) 010 degree

thanks in advance

I need to resit all my ATPL exams as they expired. I have decided to redo them and have rejoined my old school in order to do the progress tests again and be put forward for the exams.

I need to pay extra for the books but I still have my old ones. From reading on here it seems things may have changed in the theory since I did mine 5 years ago. Would my old training manuals still be relevant or have the subjects changed a lot in the last 5 years. Is there things I no longer need to study and has anything been added?

Regards

Nothing's really been added or taken away , just shifted - i.e. inertial nav is now in instruments (can't think why). You would probably find that a question database is more up to date.

phil

Hi aladdin, this question relates to turning errors on direct reading compasses. These occur not because the aircraft is turning but because it is banking, and on certain headings the compass card is allowed, because of the bank, to line up or to attempt to line up with the lines of magnetic flux which are not level with the earth's surface but dive into it at an angle of dip in excess of 60 deg at 50N. The swirl of the liquid in the compass can add to or reduce this effect. There is a good explanation here , page 7.24 on, titled 'dip errors'. I use the acronym UNOS for the northern hemisphere, meaning Undershoot on turns to North and Overshoot on turns through South

The amount to undershoot or overshoot the target heading on turns clearly depends on bank angle, dip (ie magnetic latitude) and target heading. There are various rules of thumb to allow you to estimate this. The FAA Instrument Flying handbook here contains a rather spurious explanation for turning error on page 5.12 together with some rules of thumb for this undershoot or overshoot. On page 7.22 there are some entirely different rules of thumb. In my limited experience these are both of questionable accuracy, and the example in the second case only seems to work because they choose a latitude of about 30N.

When the JAA exams started the UK CAA were asked which rules of thumb we should follow for the exams and they said 'always undershoot or overshoot by 20 to 30 degrees, irrespective of bank angle, and in the exam turns will be on to north or south'. Consequently we apply this rule for the exam, and therefore the answers to your questions should be (a) and (c).

two thirds of cruise alt for average TAS
 

Hi ,

This is really bugging me. Please help. Why do we use 2/3 of the cruising altitude for calculating average TAS during climbing (and why we use 1/2 for descent). Why this value? Where is it derived from?
Thanks in advance.

Mirkoni.

Hi Mirkoni,

First, keep in mind TAS and wind vary with altitude. In order to calculate TOC and TOD position, you need average values of TAS and wind.

During climb, your slope decreases with altitude. So you spend a half time below the two thirds of your targeted altitude and the other half above those two thirds. As a result, the average values to be taken into account regarding wind and speed calculation are the wind and the TAS at the two thirds of your climb layer.

During descent, your slope remains constant. As a result, wind and TAS can be considered as average values at the altitude corresponding to the middle of your descent layer.

Question acn/pcn
 

Hello,
Can aircraft land on runway if ACN is greater than PCN ? If yes what is the maximum difference between this values ?
Thanks

Hi! I have one question! Is there any difference between the different Oxford ATPL books issues? Especially concerning the air law... So can I prepare successfully with the older issuses ( like the 2008 edition?). Thank you in advance

Question about lift in steady climb
 

A question from PPL question bank(might be also helpful for ATPL):

The right answer is yes, the lift is less than the weight.

Why, as far as I know all the forces(resultant forces) are equal in steady climb?

http://www.theairlinepilots.com/foru...ight/climb.jpg

Apologies for using a diagram from somewhere else. In the climb the lift acts at right angles to the chord line but the weight acts directly down. The weight can be resolved into two elements, the force that opposes lift, W cos gamma, and the 'drag' element of weight W sin gamma. You can see that W cos gamma (which should show in the diagram as a vector the same length as the lift, but doesn't quite) is less than the weight, so lift is less than weight. Take an extreme case, an F15 going vertical, lift is zero, all the climb comes from the thrust.

Although this answers your question the next bit is to observe that the forces along the axis of the aircraft are Thrust in one direction and Drag and W sin gamma in the other so we can say that for a non-accelerating climb,

T = D + W sin gamma

resolving this,

sin gamma = (T - D)/weight

Which means that the maximum value of sin gamma, in other words the best climb angle, occurs where there is the greatest excess thrust over drag, VMD for a jet, and where the weight is least.

This subject is too large for a single post here.

If you do a google search for "Landing when ACN exceeds PCN", it should lead you to a link to a CAA document entitled

Criteria for operations where ACN > PCN.

This should answer your question in full.

Flight Planning - ChartE(HI)4
 

I'd need some help/opinions with the following question:

Refer to Route Manual chart E(HI)4 CAA
What is the best route from CLACTON CLN 114.55 (51°51'N 001°09'E) to MIDHURST MID (51°03.2'N 000°37.4'W)?

- UB29 LAM UR1 (given as correct answer. I can't see/find a direct connect between UB29 and Clacton)
- TRIPO UR1 LAM UR1
- UR12 (this would be my choice)
- UR123