7 ms·

What do you mean by "(and terrible practice)"?

brunohaid 1y ago
„Runway behind you“ is drilled into your head as one of the useless things in aviation. You always want to make sure to use the most runway available to you, exactly for cases when something happens. Hypothetical in this case: you realize something’s wrong with the plane, but you’re already too fast and close to the end of the runway to reject the takeoff because you wouldn’t be able to stop in time anymore. Large airports with heavy traffic sometimes have operational constraints to send a plane out ahead of another from some intersection, but if the ADSB data is correct, taking off from half the available runway in a fully loaded 787 isn’t a good idea. You just give up a ton of margin for errors.
FridayoLeary 1y ago
it means using less then the full length of runaway available. I'm not a pilot but i'm guessing that it's not good because it adds an unnecessary potential complication to the take off.
Arch-TK 1y ago
An intersection takeoff is a takeoff where you do not use the full length of the runway. When you are a large aeroplane with a full load, reaching the necessary takeoff speeds required to rotate (pull up and begin lifting from the ground) can take longer than normal, at which point the climb speed will also be reduced if not properly compensated for (e.g. you miscalculate something and set the wrong elevator trim/takeoff thrust/something else). When you are taking off, you have a short portion of the runway which you can use to abort the takeoff depending on failures, but that portion can become even shorter depending on the length of the runway. Usually the first part of takeoff you would abort for almost any reason, and the second part you would only abort in a serious emergency, once you reach a certain point you simply cannot afford to abort because you will not stop in time to crash into whatever is at the end of the runway at which point you must take-off even if you are going to immediately request an emergency landing afterwards. So if you are heavily loaded, with a lot of people on board, and you do an intersection takeoff, you are taking a risk that if you made a mistake or something goes wrong you will not have the ability to safely recover. That's why it's a terrible practice in this case. All it does is save a little bit of time which would be spent taxiing to the actual start of the runway.
- bravesoul2 1y ago
  Why is it a thing? Everything else in aviation seems to have good amounts of checks, balances and buffers. It feels the same to me as skimping a couple percent on fuel or doing less frequent maintenance. Both also reduce turnaround time.
  - Arch-TK 1y ago
    Usually some form of mis-management which in this case may have put pressure on the pilot to accept a shorter take-off option due to some minutes of time saved. Sometimes pilots also might get their priorities wrong. There's a concept of "get-there-itis" which is also a common cause of crashes but it's currently unclear if it was a factor in this case. I imagine in a while we will all be able to read the investigation reports, since the aircraft crashed shortly after take-off the black box recorder should contain all the information we need to figure out most of what happened including possibly the reasoning for the decision to make an intersection takeoff.
    - alistairSH 1y ago
      A recent, famous case of "get-there-itis" would be the 2020 Calabasas helicopter crash (that killed Kobe Bryant and several friends/family members).
  - brunohaid 1y ago
    Good question. False sense of routine, experience? Definitely a pet peeve. Was flying as a passenger on a really small airline (8 seater plane, Green Air) out of San Jose in Costa Rica. We got cleared for takeoff ahead of a United 737, at most 500 feet into the humongous runway for that plane. Yet the pilots still put in the 2 minute effort to taxi back to the beginning of the runway, even though they could have easily taken off from where we entered it. Don’t know if it was their protocol or the pilots decision, but I will trust this airline for a very long time.
    - phkahler 1y ago
      If something large had just taken off ahead of you, it was probably not safe to go anyway. Wake turbulence can kill you. If you need to wait 2 minutes, why not back taxi? It'll feel like doing something vs nothing and you get the extra extra runway.

„Runway behind you“ is drilled into your head as one of the useless things in aviation. You always want to make sure to use the most runway available to you, exactly for cases when something happens. Hypothetical in this case: you realize something’s wrong with the plane, but you’re already too fast and close to the end of the runway to reject the takeoff because you wouldn’t be able to stop in time anymore. Large airports with heavy traffic sometimes have operational constraints to send a plane out ahead of another from some intersection, but if the ADSB data is correct, taking off from half the available runway in a fully loaded 787 isn’t a good idea. You just give up a ton of margin for errors.

FridayoLeary 1y ago

it means using less then the full length of runaway available. I'm not a pilot but i'm guessing that it's not good because it adds an unnecessary potential complication to the take off.

Arch-TK 1y ago

An intersection takeoff is a takeoff where you do not use the full length of the runway. When you are a large aeroplane with a full load, reaching the necessary takeoff speeds required to rotate (pull up and begin lifting from the ground) can take longer than normal, at which point the climb speed will also be reduced if not properly compensated for (e.g. you miscalculate something and set the wrong elevator trim/takeoff thrust/something else). When you are taking off, you have a short portion of the runway which you can use to abort the takeoff depending on failures, but that portion can become even shorter depending on the length of the runway. Usually the first part of takeoff you would abort for almost any reason, and the second part you would only abort in a serious emergency, once you reach a certain point you simply cannot afford to abort because you will not stop in time to crash into whatever is at the end of the runway at which point you must take-off even if you are going to immediately request an emergency landing afterwards. So if you are heavily loaded, with a lot of people on board, and you do an intersection takeoff, you are taking a risk that if you made a mistake or something goes wrong you will not have the ability to safely recover. That's why it's a terrible practice in this case. All it does is save a little bit of time which would be spent taxiing to the actual start of the runway.

bravesoul2 1y ago
Why is it a thing? Everything else in aviation seems to have good amounts of checks, balances and buffers. It feels the same to me as skimping a couple percent on fuel or doing less frequent maintenance. Both also reduce turnaround time.
- Arch-TK 1y ago
  Usually some form of mis-management which in this case may have put pressure on the pilot to accept a shorter take-off option due to some minutes of time saved. Sometimes pilots also might get their priorities wrong. There's a concept of "get-there-itis" which is also a common cause of crashes but it's currently unclear if it was a factor in this case. I imagine in a while we will all be able to read the investigation reports, since the aircraft crashed shortly after take-off the black box recorder should contain all the information we need to figure out most of what happened including possibly the reasoning for the decision to make an intersection takeoff.
  - alistairSH 1y ago
    A recent, famous case of "get-there-itis" would be the 2020 Calabasas helicopter crash (that killed Kobe Bryant and several friends/family members).
- brunohaid 1y ago
  Good question. False sense of routine, experience? Definitely a pet peeve. Was flying as a passenger on a really small airline (8 seater plane, Green Air) out of San Jose in Costa Rica. We got cleared for takeoff ahead of a United 737, at most 500 feet into the humongous runway for that plane. Yet the pilots still put in the 2 minute effort to taxi back to the beginning of the runway, even though they could have easily taken off from where we entered it. Don’t know if it was their protocol or the pilots decision, but I will trust this airline for a very long time.
  - phkahler 1y ago
    If something large had just taken off ahead of you, it was probably not safe to go anyway. Wake turbulence can kill you. If you need to wait 2 minutes, why not back taxi? It'll feel like doing something vs nothing and you get the extra extra runway.