6 ms·

FWIW, it isn't 15 minutes of inconvenience. It's far, far more due to the traffic propagation. A 15 minute pause can result in hours of delays due to a traffic

by jjcm 5y ago

FWIW, it isn't 15 minutes of inconvenience. It's far, far more due to the traffic propagation. A 15 minute pause can result in hours of delays due to a traffic wave[0], which affects airliner takeoff scheduling as well. FAA definitely knew this and took it into account, which makes me even more curious as to the validity of the threat and what made them issue a ground order. [0] https://en.wikipedia.org/wiki/Traffic_wave https://en.wikipedia.org/wiki/Traffic_wave

skrtskrt 5y ago
Flight schedules always have slack built into them, I'm betting 15-20 minutes is probably the upper limit of what would not cause a large waterfall of issues.
- reaperducer 5y ago
  This is absolutely true. I can't count the number of times I've been on a flight where the captain said something like, "Well, we left a little late, but we'll make it up on the way there, and expect to arrive on time." I've had international flights leave an hour late and still arrive on time.
  - SEJeff 5y ago
    By default, flights are optimized for cost. Pilots can fly faster and burn more fuel to arrive at a destination (depending on reserve and bingo fuel of course) sooner. The goal is to use the minimum amount of fuel to get somewhere however and incur the most profit per passenger as a result. When you look at it, life really is an engineering problem.
    - reaperducer 5y ago
      By default, flights are optimized for cost. Decades ago, before all of the routes and scheduling got to be more of a mesh than an ideal hub-and-spoke, this was an absolute. But now, being late can cost far more money than what would be spent in fuel. Now, very often the airlines would rather burn some fuel and keep a plane on time than delay or cancel a dozen connecting flights at the destination.
      - SEJeff 5y ago
        I was noting the fact that they are able to change the speed of a plane to optimize for the specific key performance indicator they deem the most necessary at the time. I used to work in IT for delta a touch over a decade ago as a systems engineer.
      - fomine3 5y ago
        Optimize for fuel cost means that planes usually don't fly at maximum speed. It also provides margin to avoid being late by speed up.
        SEJeff 5y ago
        Precisely!
- RC_ITR 5y ago
  Yeah, a strong wind could literally cause an average delay of 15 minutes for all flights in a given area. It's not a big deal. Anyone who knows US aviation knows that its foundation is "safety over time," precisely because it's such a multivariate problem and trying to be overly fixed to a schedule gets people killed.
Retric 5y ago
This was limited to airliner taking off from a few west coast airports. That said it does take a little while for slack to get things back to normal, but no individual should have been inconvenienced by more than 15 minutes.
- tyingq 5y ago
  The words "national ground stop" are quoted a few times in the article. If that terminology got back to various airline dispatchers, it may have been more broad than a few airports.
  - Retric 5y ago
    That’s what a specific airport heard but, “Other West Coast airports contacted by CNN said they were unaware of the order.”
    - tyingq 5y ago
      Sure. Airlines will hold flights, though, on input/direction from other than a specific airport.
      - Retric 5y ago
        The original article makes it seem like a very local event from “a regional air traffic control facility” mentioning a few individual conversations with pilots. I guess in theory pilots could have said something to their airlines but that’s not a big window for the airlines to actually do anything. https://www.cnn.com/2022/01/11/business/faa-ground-stop-norad-north-korea/index.html https://www.cnn.com/2022/01/11/business/faa-ground-stop-nora...
  - AceyMan 5y ago
    It's possible that controller may have just misspoken or been fed words from another controller and said 'national' when in fact it was for the west coast centers (ARTCC) only (Los Angeles, Oakland).
rdiddly 5y ago
It means, the FAA agrees with the GP. Safety is never convenient, it's always a balancing act. For example, simply pulling out your keys (or your phone) to lock or unlock your front door is more of a hassle than leaving it unlocked. But less of a hassle than getting robbed.
- landemva 5y ago
  Article says a Cessna pilot was told to land. That is not just a little hassle in the name of safetyism, it is a diversion from the flight plan for no rational reason. From article, '... captures the controller telling the pilot of a Cessna to land ...'.
  - rdiddly 5y ago
    It's a bigger hassle to the Cessna pilot than going about his business and flight plan, and a smaller hassle than his getting caught in the middle of a jet scramble or other military response perhaps. Also, it's not necessarily entirely about the pilot's safety/inconvenience tradeoff. The Cessna IS a hassle, for anybody trying to scramble jets or launch an anti-missile interceptor or who-knows-what. The Cessna, on the ground, perhaps with its pilot quietly bitching about his ruined flight plan, is a smaller hassle.
1024core 5y ago
> A 15 minute pause can result in hours of delays due to a traffic wave[0], Anything "can" happen; but did it?

by jjcm 5y ago

skrtskrt 5y ago

Flight schedules always have slack built into them, I'm betting 15-20 minutes is probably the upper limit of what would not cause a large waterfall of issues.

reaperducer 5y ago
This is absolutely true. I can't count the number of times I've been on a flight where the captain said something like, "Well, we left a little late, but we'll make it up on the way there, and expect to arrive on time." I've had international flights leave an hour late and still arrive on time.
- SEJeff 5y ago
  By default, flights are optimized for cost. Pilots can fly faster and burn more fuel to arrive at a destination (depending on reserve and bingo fuel of course) sooner. The goal is to use the minimum amount of fuel to get somewhere however and incur the most profit per passenger as a result. When you look at it, life really is an engineering problem.
  - reaperducer 5y ago
    By default, flights are optimized for cost. Decades ago, before all of the routes and scheduling got to be more of a mesh than an ideal hub-and-spoke, this was an absolute. But now, being late can cost far more money than what would be spent in fuel. Now, very often the airlines would rather burn some fuel and keep a plane on time than delay or cancel a dozen connecting flights at the destination.
    - SEJeff 5y ago
      I was noting the fact that they are able to change the speed of a plane to optimize for the specific key performance indicator they deem the most necessary at the time. I used to work in IT for delta a touch over a decade ago as a systems engineer.
    - fomine3 5y ago
      Optimize for fuel cost means that planes usually don't fly at maximum speed. It also provides margin to avoid being late by speed up.
      - SEJeff 5y ago
        Precisely!
RC_ITR 5y ago
Yeah, a strong wind could literally cause an average delay of 15 minutes for all flights in a given area. It's not a big deal. Anyone who knows US aviation knows that its foundation is "safety over time," precisely because it's such a multivariate problem and trying to be overly fixed to a schedule gets people killed.

Retric 5y ago

This was limited to airliner taking off from a few west coast airports. That said it does take a little while for slack to get things back to normal, but no individual should have been inconvenienced by more than 15 minutes.

tyingq 5y ago
The words "national ground stop" are quoted a few times in the article. If that terminology got back to various airline dispatchers, it may have been more broad than a few airports.
- Retric 5y ago
  That’s what a specific airport heard but, “Other West Coast airports contacted by CNN said they were unaware of the order.”
  - tyingq 5y ago
    Sure. Airlines will hold flights, though, on input/direction from other than a specific airport.
    - Retric 5y ago
      The original article makes it seem like a very local event from “a regional air traffic control facility” mentioning a few individual conversations with pilots. I guess in theory pilots could have said something to their airlines but that’s not a big window for the airlines to actually do anything. https://www.cnn.com/2022/01/11/business/faa-ground-stop-norad-north-korea/index.html https://www.cnn.com/2022/01/11/business/faa-ground-stop-nora...
- AceyMan 5y ago
  It's possible that controller may have just misspoken or been fed words from another controller and said 'national' when in fact it was for the west coast centers (ARTCC) only (Los Angeles, Oakland).

rdiddly 5y ago

It means, the FAA agrees with the GP. Safety is never convenient, it's always a balancing act. For example, simply pulling out your keys (or your phone) to lock or unlock your front door is more of a hassle than leaving it unlocked. But less of a hassle than getting robbed.

landemva 5y ago
Article says a Cessna pilot was told to land. That is not just a little hassle in the name of safetyism, it is a diversion from the flight plan for no rational reason. From article, '... captures the controller telling the pilot of a Cessna to land ...'.
- rdiddly 5y ago
  It's a bigger hassle to the Cessna pilot than going about his business and flight plan, and a smaller hassle than his getting caught in the middle of a jet scramble or other military response perhaps. Also, it's not necessarily entirely about the pilot's safety/inconvenience tradeoff. The Cessna IS a hassle, for anybody trying to scramble jets or launch an anti-missile interceptor or who-knows-what. The Cessna, on the ground, perhaps with its pilot quietly bitching about his ruined flight plan, is a smaller hassle.

1024core 5y ago

> A 15 minute pause can result in hours of delays due to a traffic wave[0], Anything "can" happen; but did it?