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PHD. MBA. MHS. Type rated on A350, A330, B777, B747-400, B747-200, B757, B767, B737, B727. International Airline Pilot / Author / Speaker. Dedicated to giving the gift of wings to anyone following their dreams. Supporting Aviation Safety through training, writing, and inspiration. Fighting for Aviation Safety and Airline Employee Advocacy. Safety Culture and SMS change agent.

Wednesday, March 27, 2013

A330 and Trim

Today... Positive Stability and Trim... 

... One of the major differences between the A330 and the Boeing. 

If the Boeing aircraft was trimmed for level flight, and the pilot pulled the nose up without trimming and then released the control yoke the nose would drop, and after some phugoid oscillations the plane would stabilize at a level flight attitude. This is positive dynamic stability. 

An Airbus will not pitch down because the flight control law is G-load demand. Pulling the stick back calls for more g-load. When the stick moves to neutral the plane will stay at the pitch attitude the pilot put it. The pilot tells the plane where to go, the "man behind the curtain" runs the g-load. 

If the pilot takes their hand off the stick, the stick moves to neutral, but the nose stays were it was placed. What if the Airbus were in Alternate Law? This would mean there would be no stall protection. Low speed stability "is" available in Alternate Law, but indicated airspeed must available (along with other functions listed below). So with the loss of airspeed indication, they had lost their low speed stability. 

What does all this mean? It's all about flying the plane and always keeping your scan... even in an automated plane. It means going back to your basic instrument training and believe your instruments. If your pitch attitude says you're at 10-12 degrees in an Airbus... believe it... You are pitched up, even if you can't feel it.

While we can stall both planes Boeing takes more of an effort than an Airbus in Alternate Law. But in normal law the Airbus won't stall.

What will the future bring? Will we only train pilots how to program computers, or how to fly? Flight deck management and computer manipulation are essential under normal operations, but do not forget the power of a pilot with the ability to fly.

In our logbooks we broke apart our night and day flying, instrument and VFR (visual) flying, etc., ... Perhaps we should have a breakdown of hours with autopilot on, and those hand flown. Flying the plane makes a difference in your ability, that will carry with you forever. 

If you are learning to fly today, more than likely the majority of your training will be in an automated plane. Take the autopilot off and fly as many hours as possible. It's worth it.

Answers to yesterdays questions: 
1Why did they get a stall warning if they weren't stalling?
  • The airspeed dropped to 65 knots. And the plane thought it had stalled. Below 60 the stall warning would cease because the plane would think it was no longer flying... on the ground.
  • The stall warning is based on angle of attack not speed. However in turbulence it does not take much to bump the AOA vane to the stall warning threshold. The stall warning has an obvious margin built into it, the plane does not necessarily think it's stalling when the warning sounds... It is a warning given before things get desperate. Also at cruise Mach the stall warning threshold is very narrow (as the stall angle of attack is much lower at .82M than it is at .3M.
  • However the angle of attack is only considered valid if the airspeed registers above 60 knots. If less, you must be on the ground, right? oops... maybe  not.

  • Therefore there are several versions of alternate law , primarily 1 and 2, the main difference being the roll command mode ALT 1: roll rate demand,  ALT 2: direct law, with each having g-load demand in pitch, but that pitch law may be with or without stabilities depending on what's broken. (Confused yet?)

2.   Why did the plane stay pointed up if Keith put the controls back to Neutral?
  • The plane does what the pilot commands, and will fly wherever it is pointed.
  • Neutral Dynamic Stability.

3.   Why is it easier to stall an Airbus while in Alternate Law, than a Boeing? 
  • In alternate law the plane still trims, the pilot can't feel the control force of pitching up and stall protections are not available.
  • Loss of indicated airspeed, weight data, flap/slat position data or multiple ADR failures (or ADR disagree) can cause the loss of low and high speed stabilities. 
  •  If those are working, then there will be some back stick force required to stall the airplane, but it won't come close to the weight-lifting exercise required in a Boeing.  
4.   Why is it easier to stall a Boeing than a Airbus in Normal Law?   
  • The A330 won't allow the pilot to stall in normal law
5.   Why did Darby say put the plane on the 3 degree line? 
  • That is a good gouge for level flight. 
6.   What was that ding, and how can they make it stop? 
  • When the autothrust disengaged, it went into Thrust Lock. Until the thrust was moved out of the climb detent, the ding would occur every 5 seconds.  
  • Or click the instinctive disconnect switch and the thrust will also go to where the thrust levers are - most likely: CLB.
7.   Why didn't Keith have to worry about the autothrust being off? 
  • In Thrust lock, the plane would maintain the last power setting before it disengaged. If they remained in level flight, then the power would give them essentially the speed they had prior to the malfunction.
8.   Is Darby a Captain or First Officer? 
  • Poor Darby, she was bumped back to a first officer after the merger. Keith was the captain.  
Have you read Flight For Control? If so... have you left a comment on Amazon? I would really appreciate all the positive feedback. For those who haven't read it... check it out before the sequel releases! 
Coming soon!   

Enjoy the Journey!
XO Karlene

Thank you Bill for all your help! It's great to have someone brilliant who knows. "The man behind the curtain." 

NOTE: Bill Palmer: A330 Check Airman who wrote the systems manuals for the A330. He has a book coming soon that you won't want to miss. Until then, follow him on Facebook: And Twitter @WFPalmer  Whenever I have a technical question... he's my go to guy, and yours too.    


  1. Thanks Karlene, I have never flown a sim or real Airbus. I've talked with lots of folks who've flown, been qualified, and even tested Airbus' though I don't think I've ever read a direct comparison with a Boeing product. I have some Boeing time through various sources.

    There is much to editorialize on the benefits of the design philosophies. I don't think it really matters much in the end as long as you're aware enough to know what's going on. In the end, as I always say to guys I teach, just fly the plane instead of trying to over-think it--stick forward, houses bigger, stick back houses smaller, stick waaaaay back houses lots bigger.


    1. That's a good lesson to teach them for sure. Don't pull back too far. The plane is interesting and I really like it. Different, but good. I also wonder if it's possible to design out all possibilities of error.

      Hard to know. But, we have to keep our heads in it for sure.

  2. AhhhhhhI am so need to have this book along withthe other one because I believe the knowledge I get from it can be used to prepared me for my interview session in cadet pilot next time,

    Waaaah.... how many month you took to finish this?

    1. Thank you so much Mima! Yes... you'll learn so much for your interview! And you'll have super good luck too!

  3. Katlene you are such an interesting person! I am so inspired by reading this blog. If you ever have a layover in DTW, look me up, and we will take you for a ride in our News Helicopter we operate in Detroit. I would love yo meet you... Take care.

    1. Thank you so much Ken. And now I'm disappointed I'm not commuting to DTW. I would love to go for a ride in your News Helicopter. It's a date. I'm coming your way. Maybe not today... or tomorrow... but I'll be there. :) Thank you!

    2. Just key me know, and we will make it happen!

      Thanks, Ken

  4. Karlene, I know I was off radar for a while but wish to respond. Even though you always provide a wealth of information I am just going to reply with this: I truly love the control column/stick fly by wire systems but I must say that it truly reminds me of the iPhone. We imput the information however the response is not always what we wish the outcome to be. So maybe iPhones and Macs are like the Airbus. And My Prediction is that Darby is an FO in book two.

    1. Jeremy, you have the same problem with your iPhone! Sometimes mine takes a life of its own. Yep... poor Darby. She's lost her seniority in the merger. Such is life. Thank you so much for your comment!

  5. what is the stall speed for Airbus A330-300?

    1. In the most basic sense, the stall speed for any plane changes with weight of aircraft, configuration, altitude and temperature. So there is never "one speed."


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