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brauniger iq comp


macey2kk
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hi all,

helo me out here!!!

i have the above and am a bit confused ( easy done! )

A1 represents altitude abive sea level - A2 is zeroable to your take off point.

trouble is -- on A1 ( without being in any sort of settings menu ) i can just press the up or own button ( marker and mcready) to alter the altitude to whatever i want - therefore not showing true sea level??? is this normal??

or am i being thick?

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As you alter A1, the air pressure in mB alters as well. If the air pressure is set to the correct local value then the ASL altitude will be correct. Conversely, set the local height correctly, and by default, the air pressure value will be correct. Aircraft normally fly on the regional pressure setting, eg Barnsley or Chatham.

Remember that if your reference base (zero) is sea level, it is an altitude, if your reference base is local ground level, then it is a height. If you use the standard altimeter setting of 1013 mB and knock off the two least significant digits, then you have a flight level. I.e. an altitude of 4500 ft on an altimeter setting of 1013 mB is flight level 45.

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ahhh, the fog is beginning to lift! - thanks phil,

so....

using A2 - i climb the top of a 500ft hill, zero the display and then fly 500ft higher my display will obviously read 500ft - which is probably the one il be using most for take of and landings

using A1 - if i climb to the top of a 1000ft hill and alter the display to read zero will it then compensate and show me the true reading above sea level at the standard mb setting?

A2 is clear -- its the A1 setting that im getting confused on!

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Climb to the top of the 1000' hill , and then reset the A1 setting to 1000'. You should then have the current pressure setting in mB.

If you are talking to air traffic on the radio, you will be expected to be using the current regional pressure setting. This ensures that all aircraft have their altimeters set to the same value.

A problem arises with the Brauniger insofar as once you have started flying, I believe that the pressure setting function becomes locked. Therefore if the regional pressure setting altered whilst you were up, you would not be able to alter it. You can do a 'rule of thumb' calculation of a 1mB alteration in pressure will change your altitude reading by approx. 30 feet.

For example, you are flying at 1000 feet, on a pressure setting of 1000mB. Whilst flying, the regional pressure setting falls to 998 mB, you will actually be flying at approx. 1060 feet. In order to continue flying at 1000 feet on the current pressure setting (998 mB) whilst still displaying your previously set pressure setting (1000mB) you would have to descend to an indicated 940 feet.

Remember the saying 'High to low, look out below'. I.e. if you lower your pressure setting, while maintaining the same indicated altitude, then you will actually descend and therefore you should check below.

Hope some of this helps.

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Can we start from scratch here. Go to your flying field and enter the Regional Pressure/QNH into A1 and zero A2. Now when you take off A1 will tell you your height above sea level (ie your altitude) while A2 will tell you how high you are above your take off spot.

Example: You plan to fly from a field that happens to be 500' above sea level and then climb 1000' above that. Before take off you do as mentioned above. Now A1 will read 500' and A2 will read 0'. When you have taken off and climbed to 1000' then A1 will say 1500' (your altitude) and A2 will say 1000' (your height).

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