Principles of Flight

[Keith.Williams.]

I think that you are mixing up two very different situations.

Situation 1 Increasing IAS at constant altitude.

As we go faster the dynamic pressure increases with the square of TAS so the angle of attack and CL both decrease to maintain constant lift for level flight.

Because the CL and angle of attack are decreasing, the sudden increase in angle of caused by an upward gust will represent a greater proportional incease in CL, lift and load factor. So if we go fast enough a gust that was no problem at low speed (when the angle of attack and CL were high) will tear the aircraft apart.

So acceleration at constant altitude increases gust response, so we must not go too fast in gusty conditions.


Situation 2 Increasing altitude at constant IAS.

As we go higher at constant IAS the dynamic pressure, angle of attack and CL are constant, but our TAS increases. So any given upward gust velocity produces a smaller increase in angle of attack CL and load factor.

So climbing at constant IAS decreases gust load factor.