4 ms·

Fair dues to QANTAS for milking this on social media but spare-engine ferrying was common from the dawn of the jet age. The 707, 747, DC-8, DC-10, TriStar and

Fair dues to QANTAS for milking this on social media but spare-engine ferrying was common from the dawn of the jet age. The 707, 747, DC-8, DC-10, TriStar and VC-10 all had an underwing hardpoint for the extra engine and carrying it was fairly routine; just apply the compensations laid-out in the flight manual. Four-engined TriStars looked funny... It is rare nowadays due to the ubiquity of twin-engined airliners which have neither the underwing space nor the take-off engine-failure margin to ferry a spare. Instead their spare engines are stripped and sent in freighters, usually by the engine manufacturer who provide power-by-the-hour contracts to the airlines.

detaro 11y ago
> nor the take-off engine-failure margin to ferry a spare. What does this mean?
- kintamanimatt 11y ago
  Simply, aircraft engines are designed to be able to produce a lot more than their "fair share" of the thrust needed for flight. In the case of a twin engine aircraft, if one engine fails the other has to be able to compensate so the flight can continue safely, especially at takeoff when the plane is at its heaviest. Twin engine aircraft can easily fly with one engine out but the additional drag imposed by the ferried engine can reduce the ability for the flight to continue under the power of one engine.
  - detaro 11y ago
    Ahh, wasn't thinking of the drag aspect. Thanks!
    - kintamanimatt 11y ago
      No problem! There are other factors too, like increase adverse yaw which would become more pronounced if the ferried engine were on the same side as the failed engine.
peckrob 11y ago
I seem to recall I once flew on an L-1011 TriStar as a kid that ferried an engine. It was out of Atlanta but I can't remember if we were going to Los Angeles or San Francisco. That was probably 25 years ago, so not sure which it was. As a sidenote, the L-1011 is still one of my favorite planes. It was one of the most technologically advanced airliners ever created when it was unveiled; lots of things about it were way ahead of its time. It's a shame that the competition with the Douglas and the DC-10 nearly bankrupted both Lockheed and Douglas. Airlines played both companies against each other and nearly killed both. Lockheed ended up exiting the commercial business while Douglas merged with McDonnell. There's a great long article on the the L-1011 published a few months ago: http://www.airlinereporter.com/2015/09/requiem-trijet-masterpiece-lockheed-l-1011-tristar/ http://www.airlinereporter.com/2015/09/requiem-trijet-master...
- niccaluim 11y ago
  The L-1011 is/was amazing. It was the first airplane to be certified for full autoland in zero visibility conditions.
- bootload 11y ago
  fantastic read @peckrob ~ https://news.ycombinator.com/item?id=10873607 https://news.ycombinator.com/item?id=10873607
dalke 11y ago
Indeed it was common. Quoting from the article: > Qantas has used the Boeing 747’s ability to ferry an extra engine in the past, most recently in 2011. Qantas used the method often with their Boeing 707s when engines were less reliable, but the procedure has become quite rare.

detaro 11y ago

> nor the take-off engine-failure margin to ferry a spare. What does this mean?

kintamanimatt 11y ago
Simply, aircraft engines are designed to be able to produce a lot more than their "fair share" of the thrust needed for flight. In the case of a twin engine aircraft, if one engine fails the other has to be able to compensate so the flight can continue safely, especially at takeoff when the plane is at its heaviest. Twin engine aircraft can easily fly with one engine out but the additional drag imposed by the ferried engine can reduce the ability for the flight to continue under the power of one engine.
- detaro 11y ago
  Ahh, wasn't thinking of the drag aspect. Thanks!
  - kintamanimatt 11y ago
    No problem! There are other factors too, like increase adverse yaw which would become more pronounced if the ferried engine were on the same side as the failed engine.

peckrob 11y ago

I seem to recall I once flew on an L-1011 TriStar as a kid that ferried an engine. It was out of Atlanta but I can't remember if we were going to Los Angeles or San Francisco. That was probably 25 years ago, so not sure which it was. As a sidenote, the L-1011 is still one of my favorite planes. It was one of the most technologically advanced airliners ever created when it was unveiled; lots of things about it were way ahead of its time. It's a shame that the competition with the Douglas and the DC-10 nearly bankrupted both Lockheed and Douglas. Airlines played both companies against each other and nearly killed both. Lockheed ended up exiting the commercial business while Douglas merged with McDonnell. There's a great long article on the the L-1011 published a few months ago: http://www.airlinereporter.com/2015/09/requiem-trijet-masterpiece-lockheed-l-1011-tristar/ http://www.airlinereporter.com/2015/09/requiem-trijet-master...

niccaluim 11y ago
The L-1011 is/was amazing. It was the first airplane to be certified for full autoland in zero visibility conditions.
bootload 11y ago
fantastic read @peckrob ~ https://news.ycombinator.com/item?id=10873607 https://news.ycombinator.com/item?id=10873607

dalke 11y ago

Indeed it was common. Quoting from the article: > Qantas has used the Boeing 747’s ability to ferry an extra engine in the past, most recently in 2011. Qantas used the method often with their Boeing 707s when engines were less reliable, but the procedure has become quite rare.