5 ms·

> Engineers design pickle forks to last the lifetime of the plane, more than 90,000 landings and takeoffs, a term known as "flight cycles" in the aviation indus

by alan5 7y ago

> Engineers design pickle forks to last the lifetime of the plane, more than 90,000 landings and takeoffs, a term known as "flight cycles" in the aviation industry, without developing cracks. That number made me do a double take. Seems planes never stay on the ground for very long.

godzillabrennus 7y ago
Time is money. Hopefully autonomous vehicles used on demand see many more hours on the road than our personal vehicles.
ReptileMan 7y ago
They literally stay only the turn around time in commercial aviation in busy operations. At least that is the goal. And of course maintenence and repair. And an airframe is used over decades. Add some serious safety factor and you are up there at 90000. But since the 737 max grounding, NGs have seen more usage. So bad news for Boeing. And heaven forbid another grounding - there will literally be not enough physical planes to fly in the skies.
- quickthrower2 7y ago
  > there will literally be not enough physical planes to fly in the skies. It'd be interesting - flight prices go up and people realise they didn't need to fly as much as they thought they did?
  - ReptileMan 7y ago
    This is one of the questions I want to see answered in stimulation not in real life. There is a lot of discretionary flying, but there are place whose connection to the world is plane. You will also have route cancelations. And there will be social costs along the economical as well. All in all unpleasant situation. It will be good to have someone that understands airplanes to comment on how severe the issue is and possible remedies. The media have incentive to drum up the issues with boeing and be a tad sensationalist. From what I understood it will require disassembly of quite a big chunk of the airplane. So it will be expensive and worse slow.
    - sverhagen 7y ago
      >There is a lot of discretionary flying, but there are place whose connection to the world is plane. Are you talking about far away towns in, say, Alaska? Those may not be the kind of planes for which we're discussion scarcity, but alas. Me and my colleagues were flown for training from Oregon to one of our offices in California, this week. So was the trainer. There's still a lot of room to optimize the need for air travel.
      - elif 7y ago
        The Galapagos comes to mind. The entire economy is premised upon commercial jets landing there hourly. Puerto Rico, Bahamas, etc. Even Continental but remote tourism-driven places like Costa Rica. I think the price response to a shortage of planes would be super-linear, given that those who fly regularly are not representative of the average economic means. Prices would more than double.
        lutorm 7y ago
        Hawaii...
        elif 7y ago
        To a degree but Hawaii has shipping ports and a more diverse economy.
tus88 7y ago
One flight a day for 90,000 flights is 246 years. You are right.
- phire 7y ago
  Sometimes they fly routes that are only 30min long. With a 30min turnaround, that could mean a flight every hour. If they kept one plane flying round trips all day, they might fit 16 flights into a day and theoretically burn through the 90,000 cycles in under 16 years.
  - acjohnson55 7y ago
    Are there examples of routes like this you know of where a 737 is used?
    - markdown 7y ago
      There are routes like this, but none with anywhere near the ridiculous schedules (16 flights per day) suggested.
      - JorgeGT 7y ago
        The Madrid-Barcelona "air shuttle" by Iberia has up to 26 flights a day in each direction https://www.iberia.com/es/news-updates/relaunched-the-air-shuttle/ https://www.iberia.com/es/news-updates/relaunched-the-air-sh... but they use more than one plane. Still, a lot of cycles! In the peak hours there can be a plane leaving each 15 min. You don't need to book a specific one, just a ticket for the shuttle service and then you just turn up at any time.
    - moandcompany 7y ago
      LAX-LAS, LAX-SJC, LAX-OAK for example. Not quite 30minute flights but approaching there at ~40min and ~50min. Southwest airlines for example exclusively flies a fleet of 737-type variants. Cadence for some of these flights can be over 10x daily, in each direction. The total fleet can see 4k+ flights per day.
axaxs 7y ago
Not an aerospace engineer, but this seems like a weird way to measure airplane life. A transpacific plane could have 1/10 the cycles but equal airtime, and one would think that the stresses of flight are worth considering. Wonder why it's not measured in hours, like say, tractors, or miles flown. Do we measure any other engined vehicle this way?
- Obi_Juan_Kenobi 7y ago
  A cycle involves pressurizing the cabin relative to the atmosphere approaching flight altitude, and then depressurizing during the descent. The pressure differential may not seem like much, 6-10 psi in most cases, but the cabins are quite large, so these forces become substantial. Advanced airframes like the composite 787 use that extra strength, in large part, to lower cabin altitude (i.e. keep higher pressure) because it has such a substantial effect on passenger comfort. Cycles is absolutely the best way to consider airliner lifespan because that is the most significant stress on the airframe.
  - axaxs 7y ago
    Thank you!
- agurk 7y ago
  There are a variety of ways that age of something can be measured with two common examples in everyday life being people and cars commonly measured in years and kms/miles respectively. The metric chosen is one that adds value for understanding the impact. Aeroplanes and their components do have a lot of different ways of having their ages measured, depending upon what one cares about. Engines are a good example of something where the hours spent running is usually the most salient. For fusalages, as we're talking about here, pressurisation cycles is actually very important in pressurised airframes. This is because it is the main source of material fatigue which is a major cause of issues - usually in the form of cracks. This was discovered the hard way with the de Havilland Comet[0]. Smaller non-pressurised planes are normally measured in total flight hours, but the effect of repeatedly pressuring and depressuring is so great that it's the biggest factor that will affect the life of the bigger airframes. [0] https://en.wikipedia.org/wiki/De_Havilland_Comet#Accidents_and_incidents https://en.wikipedia.org/wiki/De_Havilland_Comet#Accidents_a...
flexer2 7y ago
Planes are extremely expensive pieces of machinery and you don't make money if you're not flying passengers with them. I'd be more surprised if they weren't in the air as many hours as possible.

by alan5 7y ago

godzillabrennus 7y ago

Time is money. Hopefully autonomous vehicles used on demand see many more hours on the road than our personal vehicles.

ReptileMan 7y ago

They literally stay only the turn around time in commercial aviation in busy operations. At least that is the goal. And of course maintenence and repair. And an airframe is used over decades. Add some serious safety factor and you are up there at 90000. But since the 737 max grounding, NGs have seen more usage. So bad news for Boeing. And heaven forbid another grounding - there will literally be not enough physical planes to fly in the skies.

quickthrower2 7y ago
> there will literally be not enough physical planes to fly in the skies. It'd be interesting - flight prices go up and people realise they didn't need to fly as much as they thought they did?
- ReptileMan 7y ago
  This is one of the questions I want to see answered in stimulation not in real life. There is a lot of discretionary flying, but there are place whose connection to the world is plane. You will also have route cancelations. And there will be social costs along the economical as well. All in all unpleasant situation. It will be good to have someone that understands airplanes to comment on how severe the issue is and possible remedies. The media have incentive to drum up the issues with boeing and be a tad sensationalist. From what I understood it will require disassembly of quite a big chunk of the airplane. So it will be expensive and worse slow.
  - sverhagen 7y ago
    >There is a lot of discretionary flying, but there are place whose connection to the world is plane. Are you talking about far away towns in, say, Alaska? Those may not be the kind of planes for which we're discussion scarcity, but alas. Me and my colleagues were flown for training from Oregon to one of our offices in California, this week. So was the trainer. There's still a lot of room to optimize the need for air travel.
    - elif 7y ago
      The Galapagos comes to mind. The entire economy is premised upon commercial jets landing there hourly. Puerto Rico, Bahamas, etc. Even Continental but remote tourism-driven places like Costa Rica. I think the price response to a shortage of planes would be super-linear, given that those who fly regularly are not representative of the average economic means. Prices would more than double.
      - lutorm 7y ago
        Hawaii...
        elif 7y ago
        To a degree but Hawaii has shipping ports and a more diverse economy.

tus88 7y ago

One flight a day for 90,000 flights is 246 years. You are right.

phire 7y ago
Sometimes they fly routes that are only 30min long. With a 30min turnaround, that could mean a flight every hour. If they kept one plane flying round trips all day, they might fit 16 flights into a day and theoretically burn through the 90,000 cycles in under 16 years.
- acjohnson55 7y ago
  Are there examples of routes like this you know of where a 737 is used?
  - markdown 7y ago
    There are routes like this, but none with anywhere near the ridiculous schedules (16 flights per day) suggested.
    - JorgeGT 7y ago
      The Madrid-Barcelona "air shuttle" by Iberia has up to 26 flights a day in each direction https://www.iberia.com/es/news-updates/relaunched-the-air-shuttle/ https://www.iberia.com/es/news-updates/relaunched-the-air-sh... but they use more than one plane. Still, a lot of cycles! In the peak hours there can be a plane leaving each 15 min. You don't need to book a specific one, just a ticket for the shuttle service and then you just turn up at any time.
  - moandcompany 7y ago
    LAX-LAS, LAX-SJC, LAX-OAK for example. Not quite 30minute flights but approaching there at ~40min and ~50min. Southwest airlines for example exclusively flies a fleet of 737-type variants. Cadence for some of these flights can be over 10x daily, in each direction. The total fleet can see 4k+ flights per day.

axaxs 7y ago

Not an aerospace engineer, but this seems like a weird way to measure airplane life. A transpacific plane could have 1/10 the cycles but equal airtime, and one would think that the stresses of flight are worth considering. Wonder why it's not measured in hours, like say, tractors, or miles flown. Do we measure any other engined vehicle this way?

Obi_Juan_Kenobi 7y ago
A cycle involves pressurizing the cabin relative to the atmosphere approaching flight altitude, and then depressurizing during the descent. The pressure differential may not seem like much, 6-10 psi in most cases, but the cabins are quite large, so these forces become substantial. Advanced airframes like the composite 787 use that extra strength, in large part, to lower cabin altitude (i.e. keep higher pressure) because it has such a substantial effect on passenger comfort. Cycles is absolutely the best way to consider airliner lifespan because that is the most significant stress on the airframe.
- axaxs 7y ago
  Thank you!
agurk 7y ago
There are a variety of ways that age of something can be measured with two common examples in everyday life being people and cars commonly measured in years and kms/miles respectively. The metric chosen is one that adds value for understanding the impact. Aeroplanes and their components do have a lot of different ways of having their ages measured, depending upon what one cares about. Engines are a good example of something where the hours spent running is usually the most salient. For fusalages, as we're talking about here, pressurisation cycles is actually very important in pressurised airframes. This is because it is the main source of material fatigue which is a major cause of issues - usually in the form of cracks. This was discovered the hard way with the de Havilland Comet[0]. Smaller non-pressurised planes are normally measured in total flight hours, but the effect of repeatedly pressuring and depressuring is so great that it's the biggest factor that will affect the life of the bigger airframes. [0] https://en.wikipedia.org/wiki/De_Havilland_Comet#Accidents_and_incidents https://en.wikipedia.org/wiki/De_Havilland_Comet#Accidents_a...

flexer2 7y ago

Planes are extremely expensive pieces of machinery and you don't make money if you're not flying passengers with them. I'd be more surprised if they weren't in the air as many hours as possible.