incorrect AoA gauge optimum indicator position

[callmepartario]

The picture on the right is from the A-4E NATOPS manual. In the aircraft the optimum indicator is at 16.0 units. In the NATOPS, the optimum indicator is at 17.5 units (located at the 3:00 position on the dial).

[sdreagan]

I flew several versions of the A-4. Starting out with the TA-4J in the training command (Beeville) then later the A-4E/F and the Super Fox (A-4F with P408 engine). My total time in the A-4 is not high, maybe 500 hours. The reason I bring this up is that this really fine Module has an error in the AOA gage. Optimum landing speed in the A-4E is at 17.5 units, The gage in the cockpit has the OPTIMUM indictor (vertical rectangle with tick at 0900) at 16.0 units. The needle does point to 17.5 units when the indexer shows the yellow donut (OPTIMUM indication). But the needle and 17.5 units location on the dial are at the 2:30 position on the gage. The correct presentation should have the gages' OPTIMUM indicator and the needle at 17.5 units both at the 3:00 o'clock position. That way when level in the carrier pattern at 600 feet on downwind at Optimum AOA the needle is pointing directly at 3:00 which is also pointing directly at the VSI needle which is pointing directly back at the 09:00 position. So, they are pointing directly at each other. It's designed that way to make the scan easier. Especially for the turn off the abeam position towards the grove and the ball. Everything is very precise, and the scan is easier to read when presented that way... As you turn into the grove and pick up the ball you want your altitude to be just right... It only gets that way because you have controlled your altitude precisely and you've done that because you've controlled your VSI and AOA precisely as well.

[sdreagan]

I'm adding a video to help describe the issue. https://1drv.ms/v/s!AlwQEzXCJXxZheNsb2AQ1OW-6VWpQw?e=y4lsWq