The pitch indication (artificial horizon).

[mbenkhort]

Hi everybody!

How much does pitch indication (given by the attitude indicator) help in navigation?
I am asking this question because I consider that the value of the expression of pitch : theta = AoA + flight path (angle gamma) , can be the same for different configurations of flight.

[mad_jock]

As nobody else has bitten I will try.

If you mean navigation getting from A to B then pitch doesn't really come into it.

But performance it does for a given stage of flight, pitch plus power equals performance. I know that for certain attitudes and power settings and zero rate of climb will give me a certain airspeed. So if we have a instrument failure I know I only have to set up the variables I know and the others will sort themselves out.

HAve I got the right end of the stick with your question?

[mbenkhort]

Thanks mad_jock,
heplfull your answer is. I understand that knowing pitch value is of a help only if used with other readings such as rate of climb/descent, speed etc.
If for instance , during a dark night, one has at his disposal only pitch and speed values, he cannot precisely insure that he is climbing, descending or in a level flight. A 5 degrees pitch reading can mean for instance eather a "2 degrees climb path at an AOA of 3 degrees" or a " 2 degrees descent path at an AOA of 7 degrees".

[mad_jock]

You can know that thought that with a certain pitch and power setting eg 15deg nose up and max power that the aircraft will be climbing at Vx.

Now you are correct though that if you were in a downdraft which was more than the climb rate at Vx you would be going down not up. But there ain't alot you can do about that if you are a VX anyway and max power.

The angle of attack of the wing in normal flight will be directly related to pitch. Unless we are talking about gradients for terrain seperation or approach it isn't normal to try and achieve a set gradient. You may want a certain climb rate to achieve a gradient which will depend on your ground speed. The setting an attitude and power equals performance will set up your aircraft to achive rates of climb, speeds etc as if you were in still wind.

If you start wanting to relate that to using the ground as your reference you will have to do some mental calculations to figure out what you actually need to get your required gradient. You can use timings or 1 in 60 rule to figure it out.

[bingofuel]

If you have a known power setting and a known pitch setting then your speed will be (within some tolerance) a fairly stable figure.

However, as you say, knowing pitch and speed doesn't tell you very much apart from the fact you are still moving forwards as the climb or descent part of the 'performance' will depend on the power setting.

That is why it is quite possible to fly an aeroplane with no airspeed indication if you know the rough power and attitude settings for various speeds and configurations.

Similarily you could set a pitch attitude and then adjust power to achieve a speed and either climb / descent or level flight if you had no power indications,

However as MJ rightly says, the basic phrase power + attitude = performance works for most circumstances