JAA PPL Question
 

Hello all,

I'm studying for my JAA PPL and one question that I couldn't understand. Any help is mostly appreciated.

a pilot setting off on a cross-country route in a cruise climb over a part of the country where the transition altitude is 3000 feet, has just been given a regional pressure setting of 970mb (hpa), from a local ATSU. His magnetic track is 260. What will be the transition level and what will be lowest avialable Flight Level that the pilot can use, in accordance with the quardrantal rule? (Note assume that pressure falls with increasing height by 1 mb every 30 feet)

a. FL 45 FL 60
b. FL 40 FL 55
c. FL 30 FL 30
d. FL 45 FL 55

Transition level is the lowest flight level with 1013 mb set on the pressure altimeter.

In the question, the pressure on the day is 970 mb which is 43 mb lower than standard 1013. The question asks you to assume a pressure difference of 1 mb per 30 feet, hence:

43 x 30 = 1290 feet. This is by the way the transition layer.

3000 feet transition altitude + transition layer of 1290 feet = 4290 feet.

The lowest flight level which can be used on the day is therefore FL45.

The second part of the questions asks you for the correct flight level according to quadrantal rule.

You will be flying a heading of 260 which will therefore be a postive flight level. The first positive flight level will be FL60.

Your answer is A: FL45 Transition Altitude and FL60 Flight Level.


Hope that helps.

As with many of those questions, much of the information they give you is superfluous. Going SW using the quadrantal rule it must be an even FL There's only one in the options given. In an exam its worth checking the answers first, saves time for other questions! Having said that, good explanation above ^

Not wanting to nitpick at G CEXO's answer, because its perfectly correct, I think he meant flying an "Even" flight level when he said "positive" flight level.

Hopefully ALL flights levels are "positive"...

Magnetic track=
0 - 89 : Odd thousands of feet (FL30, FL50)
90 - 179 : Odd thousands + 500 ft (FL35, FL55)
180 - 269 : Even thousands of feet (FL40, FL 60)
270 - 359 : Even thousands + 500 ft (FL45, FL65)

With the plan to raise the TA to 18,000ft it will all soon be history.

Whilst the correct answer is arrived at, I would dispute a couple of the statements in G-CEXO's explanation.

The Transition Level is more usually defined as the first 500ft level above the Transition Altitude; it is not a usable cruising level as it will not provide adequate separation from an aircraft cruising at the Transition Altitude. Consequently, whilst the Transition Level in this example is, indeed, FL45, the lowest available cruising level is FL50. This would be significant if the aircraft's track was north westerly as the minimum quadrantal level would be FL65 and not FL45.

The Transition Layer is the vertical distance between the Transition Altitude and the Transition Level which, in the example given, is 210ft



-----------Transition Level------------------ 4500ft 1013mb - FL45
Transition Layer (4500-4290=210ft)
----------Transition Altitude----------------- 3000ft 970mb (4290ft 1013mb)

^
3000ft
v

----------------MSL------------------------- 0ft 970mb (1290ft 1013mb)
^
1290ft
v
------------------------------------------- -1290ft 970mb (0ft 1013mb)

Yes, I actually meant even FL.

It's been a while since learning all this crap. Yes you're right, the Transition layer is actually 210 feet.

So what's going to happen if you want to fly IFR in a light a/c? That is, what altitude rule will we use?

Yes, almost 50 years in my case.