In aviation, what are the triangles of agreement?

Question

In aviation, what are the triangles of agreement?

Answer 1

Triangles of agreement

It has to do with Instrument flying, and how you know when your instruments are lying.

The answer is to cross-compare information sources. If your airspeed is increasing, a check of the attitude indicator, altimeter, and VSI may confirm that you are indeed in a descent. Is there a question about your bank angle? The attitude indicator, turn coordinator, heading indicator, and magnetic compass can help to resolve it — although many would say that the magnetic compass is all but useless in anything other than turbulence-free conditions.

Has the airspeed dropped off? Perhaps the tachometer will show a reduction in power — maybe because the throttle friction lock has inadvertently backed off, or maybe because you've picked up some carburetor ice.

The point is that there are multiple — usually three — additional sources of information about pitch, bank, and power, over and above the gauge you've been fixating on. Call them triangles. Cross-checking them will usually resolve your situational awareness with regard to attitude, airspeed, and power.

If any of the triangles contain elements that don't agree, then you have a problem. Let's say your attitude indicator shows you in a descending left turn, but your other pitch instruments (altimeter, VSI, airspeed indicator) give evidence that you're in level cruise. Let's also say that your heading indicator is showing a turn to the right at the same time, but your turn coordinator and magnetic compass are showing you wings level. You must rule out the attitude indicator and heading indicator. Their information has been outvoted by the rest. It's very possible that your vacuum or pressure pump has failed, leaving you without gyro power to those very critical instruments. In this case, a check of the vacuum or pressure gauge will show a too-low reading.

Hope this helps..

Answer 2

Huh?