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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, August 1, 2012

A330 DriftDown... A Reason for Everything

Losing an engine at altitude over the ocean is an uncommon experience, but not improbable. And when it happens to you, will want to be prepared. Operationally you can memorize what to do. But the problem with rote memorization is the added stress of "This can't be happening!" combined with fatigue, and perhaps a few months of sitting reserve and not flying, and you miss one step... the remainder of the procedures head south.

B-6088 of Hainan Airlines flying over you guessed it – the Museum of Flight last 9 March

While I'm busily studying for recurrent, I decided to dissect the driftdown procedure in hope to provide an understanding for greater recall. The process first, then the reasons why.
  1. Set MCT and disconnect autothrust.
  2. Turn off the track 180 degrees, while slowing at altitude.
  3. Select Green dot.
  4. Determine your drift-down altitude. 
  5. At or approaching Green dot, pull for open descent. 
  6. Turn on your lights
  7. Select "Below" on TCAS. 
  8. Communicate.
  9. Re-establish auto-thrust and select desired speed. 

  • Your goal is to minimize the descent rate. Setting MCT will provide the lowest possible descent rate until you are clear of traffic. Why do you turn off A/T? Soon you'll be selecting open descent and you do not want the good engine to go to idle. So you're getting ready.
  • Turn off the airway 180 degrees. We have to get 15 miles off course to avoid traffic, and want to initially fly parallel to the course. Why 15 miles? Because for RNP10 (another plane could have a 10 mile error, plus a 2 mile offset) we could have traffic 1000 feet below, as far as 12 miles off our course.  The first 90 degree turn at .80 Mach will take about 8 miles. The second 90 degree turn will take another 8 miles. Two 90 degree turns equal 180 degrees and you will be very close to that 15 miles. Adjust as necessary.  
  • Select green dot speed. You've already been slowing that direction while maintaining altitude... time to set the bug. This is the speed you want to fly the initial driftdown. 
  • Driftdown Altitude: 
    • PERF Cruise altitude is the maximum altitude at green dot speed.
    • PROG page is REC MAX. The altitude you can fly EO LRC. 
    • Note: Engine out Managed speed is EO LRC in level flight, and green dot in climb and descent.
  • Open Descent. Since your thrust is in MCT, this will provide the lowest possible descent rate. (If you forgot and left the A/T on, the thrust would go to idle.) If you pull for open descent prior to green dot, the plane will start down a couple hundred feet per minute, which is fine.
  • Turn on your lights so everyone can see you coming. 
  • TCAS to "below" enables you to see traffic below you down to 9900 feet. 
  •  Communicate. Thanks to ADS and CPDLC... life is easy. ATC com Emergency page Set ADS:OFF to ADS:ON. Similar to squawking 7700... this sends a position report every couple minutes.  CPDLC you can send your intention of the altitude you're descending to as well as selecting PANPAN.
  • Re-establish auto-thrust and select desired speed. Once you are off track 15 miles, you want to get below the tracks quickly so you can continue to your alternate. Thus if there is no terrain issues then you can expedite your descent below FL290... to FL280 to fly direct to your destination. You do not want to fly across the tracks at altitude. If you leave the power in MCT, you'll continue with a gradual descent and this descent will take forever. So you can re-establish auto-thrust and select desired speed to get down and on your way quickly.
Even when you lose an engine you can enjoy the Journey!

XOX Karlene

Above is a photo that I had originally placed at the top of this post. One of my friends emailed me and asked me to replace this photo with the A330. But of course. 

My thought is this... could you imagine any of these planes coming down on top of you? We fly over  each other daily. When we have to go down... this could be an issue if we don't know what we're doing.


  1. Just e-mailed you a photo to replace the top one... gratis.

    Keep on keeping on writing & flying.

    1. Got it. Posted. And... a comment. Thank you Josef!!!

  2. when descending with an engine failure, can you use the speed brakes to expedite the descent?

    1. You technically could. I suppose. But you wouldn't. Unless you had a runway under you and you had an uncontrollable fire on board. Then that would be an option to get down really fast. But in this scenario, we want the most efficiency.

      Imagine the drag of the other engine hanging out there not producing thrust, and then adding more drag with the spoilers.

  3. Wow, enjoying the journey while losing an engine, now THAT is positive thinking! ;)

    1. Well, if you live to tell about it. Life is good. :) Thanks for stopping by Heather.

  4. I lost one once, but since I only had one to start with, my procedures were a bit more hurried :)

    (for anyone who is curious, I did get it going again)

    1. Oh... so nice to get the engine back when you only have one. Yay!!!

  5. Karlene, thanks for a very informative post. I could write another novel but will hit on one of your crucial points: COMMUNICATION. IT'S one thing to have an emergency for your flight but to create one of others is disastrous. Not only communication to the radio traffic centers but also amongst crew on the deck and in the cabin. Also the ADS: ON feature is great as it sends multiple position reports to help eliminate any possibility of coming in contact with surrounding traffic as there is a margin of area or error on the airways due to winds traffic and other factors. Oceanic crossings are an awesome thought to me but loosing an engine especially ETOPS is quite scary. Non aviation people ask me about it all the time ie loosing an engine over water. Thanks to you I can show them this to let them know that pilots know what they are doing!

    1. Thank you Jeremy. Yes... communication is a key. And when both pilots are on the same page... standard operating procedures, some of that communication is complete with the "known." And for the extra little communication boxes... oh, so nice to let ATC know what you're doing and where you are without having to try to talk on HF. Simplifies everything! Thanks for your comment!!!

  6. Your tutorials based on your own study guides that you develop always sound excellent to me. I'm sure flyers who read this blog appreciate them MUCH!

    1. Thank you Linda. I don't invent this stuff. Just use the experts and then put it in a format my brain can remember. Thanks for your comment!

  7. Hmmmm, One little item I didn't see and to some in Sim-City it looms large....confirm & verify WHO is flying the aircraft and who is doing the diagnosis, math, configuration and brain-work. It is that whole 'Flight for Control' thing (chuckle).

    More often than not pilots LOVE to be the hero and jump right in to solve problems (think EAL 401 L1011 in the Everglades) and the whole flight deck-team get out of the loop flying the aircraft (hmmmm NWA188?). Not being versed in airbus procedures but I do think there is some sort of electronic equal to the old Beech 'throw-over yoke' days.

    Just a heads up K for your time in the box.


    1. Definitely... a must! Who is flying. I heard a person speak at a conference at OSH who said, "With two first officers flying together, there is ambiguity who is flying the plane." I say, "Not true." One person flies, the other handles the radios. The rest of the stuff, lights, TCAS, etc.= a team effort. If we both know we need to do it, it will get done.

      Thank you so much for the great comment! And proven that we do need to know who is flying the plane.

  8. I'd have to say "True" regarding the two FO's IF there was not a positive statement re-affirming the roles of the PF/PNF. Remove all doubt and press-on with the recovery.

    Every FO is a heartbeat (and a few thousand seniority numbers) away from being a "Captain'.

    Tim (TDY MT)

    1. Oh... so true. And some think they are. And others, should be. And for some we say, "It's time to get your own plane."

      Probably the most frustrating thing from a FO's perspective is flying with a captain who shouldn't be. Then we need to pull all our CRM tools out of that bag.

  9. Hi Karlene! I fly the a320 and we have the same procedure for the driftdown...turning autothrust off after setting MCT. But doesn’t MCT take the autothrust off anyway? IOW, when you go MCT the autothrust Operation on the right side of the PFD goes from White(Active) to Blue(Arm). So why would the engine roll back at green dot. It’s the same thing on takeoff. Your Autothrust doesn’t engage until you pull the levers back to Climb detente.


    1. Hi Louie, Thank you for the comment! Now that I haven't flown the Airbus for 22 months, I'm going to think long an hard about this. Thanks for your thoughts. Now... come to the B777 and help me figure this system out. :)


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