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"We are the protagonists of our stories called life, and there is no limit to how high we can fly."

Type rated on A330, B747-400, B747, 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.

Thursday, August 30, 2012

Flying the Plane fully Managed

We've been busy taking care of the little ones here in Cyprus... and not sure if the wildlife is more wild with a two and a half year old being all boy running around the house, or the 9 month old crawler...

But, I do know that whether the goats are cresting the mountain top, or the critters are playing in the house at night, life is an adventure.

Bone photography is in full progress... Not your normal kitchen table.

And who said flying the A330 was a challenge? But if you are flying it we're on Day 3 of a six week segment on the phases of flight.

Flying Fully Managed
It’s important to remember that managed speed is available whenever the AP or FD is on, regardless of the engaged mode … and even without AP or FD if you’re in the approach phase. This means that automatic selection of speeds is not only available in managed descent (VNAV) but also in OP DES. This is in contrast to the Boeing requirement of selected speed when in FL CH (i.e., not in VNAV).

Approaching 10,000 feet in the descent on the A330

Managed speed will automatically reduce to 250 for descent below 10,000’. No pilot action is required. This value is set in the speed limit field on a vertical revision page.

The Boeing model uses the “on approach” phase for the final approach. The Airbus approach phase applies to terminal operations below 250 knots, so it’s a slightly different focus.

To slow further, without manual selection, activate the approach. The approach can automatically activate itself, but it is not common in today’s ATC environment.

Automatic approach activation occurs if the airplane flies over the DECEL point in managed nav (the DECEL point is depicted as a D with a circle around it).

There are some minor exceptions to this but that is the basic idea. If the conditions are met for automatic activation, the DECEL point will appear in magenta, otherwise (for example, when in heading select) it will be white.

In a situation where you are flying a fully managed arrival (managed nav and managed descent engaged) and fly over the magenta DECEL point, the magenta speed bug will automatically move from 250 to VAPP. Your actual speed will be dependent upon aircraft configuration. The DECEL point is calculated to provide enough room for a continuous deceleration to approach speed on final.

The approach phase can also be manually activated at any time during the climb, cruise, descent, and go-around phases with the ACTIVATE APPROACH prompt on the current PERF page.

Question number three on your quiz Tuesday, the answer was the target speed would be VAPP. But the airplane will only initially slow to Green Dot after the approach is activated.

The target speed, the magenta bug, will be at VAPP. and usually off the bottom of the speed scale at the time of activation, therefore will appear as a number below the airspeed indicator. The number disappears when the speed bug is visible again. Therefore, the target speed is indeed VAPP, and the airplane “wants” to slow down to that speed. But the autothrust has speed limits. 

On the low side the speed limit is the maneuvering speed for the current flap selection. With the flaps up, the autothrust maintains a minimum speed of Green Dot even though the target speed is VAPP. With flaps selected at 1, the minimum speed will be S speed, and so on.

With managed speed engaged, you could tell if the approach phase was active by looking at the target speed on the PFD. If the magenta bug is at VAPP, then the approach phase is active. If the cruise or descent phase was still active the target speed would be 250 (assuming you’re below 10,000 ft).

With the target speed at VAPP, the airplane is trying to slow down when given the opportunity, and flies at the most economical speed for the current flap setting until it can slow further.

How does Airbus calculate Vapp? Take a guess... and next week I'll share that answer.


  1. My guess is that VAPP would be calculated by using the distance from the current location of the aircraft being to the arrival point/airport? I hope I am within ballpark range :) excellent post and thank you for sharing your abundance of knowledge!

    1. Actually Vapp is not a speed calculated by a distance. Think about this. If you were 15 miles from the end of the runway and your approach speed is say, 140 knots. Now you are 1 mile... would your approach speed change because of distance? Could you fly slower because you are 1 mile verses 15?

      As the case may be, I think I'm glad the airplane figures the magic number out, and not me. :)

    2. Good point. I will rethink my answer. I don't know why my mind keeps thinking distance. I can't believe I am saying this but I wish I had my simulator back so I can try working this out. This time using a better FMS than what I was using. My only other guess at this point would be altitude Rate of descent + approach path/STAR heading.

    3. Hi Jeremy, Okay... think about this. How much does a Cessna weigh verses an A330? I don't remember exactly, but I'm thinking a 172 final is 60-65 knots? What would happen if a 300,000 lb plane tried to fly at those speeds? There in lays the clue.

    4. Ahh... now is another "why didn't I think about that / how could've I not thought of that" moment. At 300K, that plane would stall into an oblivion going on a 172 final? So my guess now is that weight and size of the plane is calculated in the FMS for VAPP to prevent the plane from doing this. Looking forward to the answer next week.

    5. Now we're thinking. Those engineers are brilliant folks.

  2. I'm not afraid of spiders, but in this case, I'll make an exception. Yikes!

    1. Yes, be afraid. Be very afraid. And the Ants... they are big and come out at night. Feet off the floors and make friends with them. It's the only way.

  3. Wow, you really are having an adventure! And working hard at the same time, as always. ;) The little ones are growing so fast!

    1. They are growing so fast for sure. This is definitely an adventure.


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