PPRuNe Forums - Testing the A320

I had the opportunity to fly the A320 and A340 on course and found them both very good. Whilst discussion surrounding Airbus types is generally in comparison to Boeing, I found it to more complex. I offer the following thoughts.

1. Sidestick v control column. Issues of how does non-flying pilot (NFP) know what FP is doing. Transfer of control no longer entirely visual (can't mistake someone beside you grabbing the control wheel). Summation of both pilots inputs into FBW system is a problem (A320 a floating down Sydney runway with full up and full down commands from each side - FBW summed and got 0).

2. FBW law. C*u as they call it. It's supposed to be a blend of pitch rate and G command, however is mostly G command and you see it as a flight path hold. (Decelerate on finals, GP remains constant, nose attitude raises without input). Look for gust response, apparantly it will pick up a gust induced down wing without pilot command. Chance for PIO I think, though not able to confirm due smooth conditions.

3. Flight Envelope Protections. Hard v Soft limits. Fixed limits for Airbus, whilst Boeing has soft limits. Prefer the Airbus. Consider where the limits are. 60AoB, 20NU or ND(?). This is not a sustainable attitude for a large aircraft. Having flown the 777 sim, all you prove by going beyond Airbus hard limits is that U/A recoveries in large aircraft will overspeed/stress. Trap here is that if the Airbus does flip (A330 @ Toulouse) it reverts to mech mode in which it is now possible to stall (ie above alpha max).

4. Autothrottles. Not back driven. A bad thing, especially with quite engines. Amidst confusion in moding etc etc, easy to lose track of what the engines are doing.

5. Lateral Control Law. Deflection = Roll rate command. (max deflection = 15deg/sec ?). Consider EFATO, and balance forces. Left with residual roll moment that traditionally is balanced with control wheel deflection during SL flight, ie deflected wheel but no roll (rate). On Airbus no roll rate means no stick deflection, the computers sort it. So no feedback of impending Vmca departure (unless you watch the control deflections page). I found I PIO'd in roll during every EFATO trying to establish 5 deg AoB toward the live engines.

6. Threshold Speed Accuracy. IAS accuracy and flight path accuracy are almost at opposite ends of the LSS spectrum. Consider the F/A-18. Gear up G command for combat missions, gear down, strong LSS for accurate IAS onto deck. Airbus approach to land in flight path command. So look at accuracy of speed control (and wonder why they recommend using auto throttles on for all landings!). Have ago at manual throttles.

All said and done, I prefer the Airbus. The Boeing v Airbus debate is not factual. No-one blames Boeing flight control laws when an aircraft crashes short of the runway with AEO because it got slow, however this is a classic LSS response. Have fun.