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MohawkWeekend
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Taxi and Delay Times

Wed Mar 10, 2021 4:02 pm

Not sure if this has been discussed previously or might be in the Technical Forum. Do the airlines track time from engine start to takeoff? Similarly from landing to shut down? Do they put a price on this? With the coming push to reduce aviation's greenhouse gas emissions, reducing these times would be IMO low hanging fruit.

It would be interesting to see how major airports rank in this metric. (ORD vs ATL etc.)
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    mjgbtv
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 4:09 pm

    No idea on metrics, but given how much these times can affect passenger experience, operations and fuel cost I would think any low hanging fruit in this area would have been picked long ago.
     
    asuflyer
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 4:17 pm

    Yes at the US majors these metrics are tracked extensively for operational and efficiency purposes, station and on-time performance and also compliance with the DOT Tarmac 2 hour rule.
     
    maps4ltd
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 4:27 pm

    I look on Flightaware frequently for taxi times (one of the few things they do better than Flightradar24). Big hub airports can easily have 30-40 minute outbound taxi times during banks. Same with deicing during the winter (you can frequently see taxi times in excess of an hour due to heavy traffic, a snowstorm, or both).

    As for inbound taxis, ORD and DFW seem to have some of the longest. In particular 17L/35R at DFW and 9L/27R at ORD.
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    russyyz
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 4:43 pm

    I understand that YYZ also tracks this data and provides it back to the airlines in order to help all parties improve all processes.
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    JoseSalazar
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 4:54 pm

    All flights are tracked with automatically logged OOOI times (out off on in, but often pronounced as it looks, “ooey”). Different triggers exist at different airlines, but generally it’s pushback for out (triggered by the doors being closed and the parking brake being released, though some are apparently triggered by wheel movement), weight off/on wheels for off/on, and parking brake set at final stopping place, door open, for in time.

    I assume engine time/cycles are logged independently, but for the purposes of measuring taxi time, that’s the difference between out and off times, and on and in times. They also track how much of that time engines are running. Each captain (and the whole operation) is tracked to monitor single engine taxi time and APU usage at some places.

    As far as it being low hanging fruit, if there’s an average taxi time of say 45 mins (we can get our airline’s average or most recent aircraft’s taxi time at that station through an automated system...), or we just see there’s a long line, that may dictate if 1 or 2 engines are started at the gate. But we won’t delay a pushback or engine start, as you generally don’t get in the takeoff queue until you initially call for taxi. Also, being delayed from pushing back matters with on time stats (D0), but being delayed on the ground doesn’t so long as you get out on time. It does burn more gas, but there isn’t a lot you can do about that. So, shortening taxi times is pretty tough at big airports where long delays are normal, and is not exactly low hanging fruit, from an operational standpoint. The only real way to do that is to further slot control arrivals/departures, or avoid busy times, and I don’t see that happening operationally. They just build in the historical longer times into the cost/scheduling equations.
    Last edited by JoseSalazar on Wed Mar 10, 2021 5:02 pm, edited 2 times in total.
     
    Scarebus34
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 4:54 pm

    MohawkWeekend wrote:
    Not sure if this has been discussed previously or might be in the Technical Forum. Do the airlines track time from engine start to takeoff? Similarly from landing to shut down? Do they put a price on this? With the coming push to reduce aviation's greenhouse gas emissions, reducing these times would be IMO low hanging fruit.

    It would be interesting to see how major airports rank in this metric. (ORD vs ATL etc.)

    Yes. They track single-engine taxi, apu usage, etc...
     
    alasizon
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 4:56 pm

    Yes, Taxi-In (TXI) and Taxi-Out (TXO) are tracked extensively.

    When each flight is scheduled for a particular block time, that includes the estimated TXO and TXI which is based on historical trends at a given airport for a given hour and expected runway flow patterns. Sometimes planned gating assignments are also taken into account but that is only on specific flights and is more often based on a carrier's need to shift times a few minutes here and there for either connections or slots.

    Every minute of planned block costs money and every unplanned minute of block costs even more.

    Having recently been dealing with a spike in TXI, I can assure you it is not just low hanging fruit but something that is monitored so closely that a single minute average change drives conversation on the why and requires a lot of analysis unless something is blatantly obvious.
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    Woodreau
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 5:25 pm

    It is definitely tracked. to the point fuel planning is provided for taxi out.- historical average for taxi out for each individual flight.

    - not so much for taxi in for fuel planning purposes - though the airline does know the average taxi in time as well.
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    zuckie13
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 6:06 pm

    Woodreau wrote:
    It is definitely tracked. to the point fuel planning is provided for taxi out.- historical average for taxi out for each individual flight.

    - not so much for taxi in for fuel planning purposes - though the airline does know the average taxi in time as well.


    This is probably the biggest reason - making sure they have sufficient Taxi Out fuel to be legal to depart. Need to know the trends at airports to do that right.
     
    VSMUT
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 6:27 pm

    MohawkWeekend wrote:
    Not sure if this has been discussed previously or might be in the Technical Forum. Do the airlines track time from engine start to takeoff? Similarly from landing to shut down? Do they put a price on this? With the coming push to reduce aviation's greenhouse gas emissions, reducing these times would be IMO low hanging fruit.

    It would be interesting to see how major airports rank in this metric. (ORD vs ATL etc.)


    I have yet to meet a pilot who didn't try to get to the runway and into the air as fast as possible.

    Most aircraft logs that I have seen have fields for off/on block times and takeoff/landing. Block time is pretty much the same as engine time, typically starts when you begin pushing back and ends when you set the parking brake. Flight data monitoring has given the airline a way to get this data more precisely.

    Low hanging fruit, maybe. It is better to wait on the ground than in the air over the destination. Eurocontrol does a pretty good job at slotting aircraft so the wait is at the runway and not in a holding pattern at the destination.

    In my experience, Flight Data Monitoring is actually being used to the opposite effect, slowing taxi speeds down. Management at many airlines see it as a risk along the same lines as handflying the aircraft.
     
    MIflyer12
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 7:23 pm

    MohawkWeekend wrote:
    Not sure if this has been discussed previously or might be in the Technical Forum. Do the airlines track time from engine start to takeoff? Similarly from landing to shut down? Do they put a price on this? With the coming push to reduce aviation's greenhouse gas emissions, reducing these times would be IMO low hanging fruit.

    It would be interesting to see how major airports rank in this metric. (ORD vs ATL etc.)


    How do you think that carbon cost is going to compare to the costs of dozens of $80 million assets sitting there, waiting to take off? How do you think it will compare to fuel costs in the U.S.? If they could put planes in the air faster, they would.
     
    MohawkWeekend
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    Re: Taxi and Delay Times

    Wed Mar 10, 2021 9:09 pm

    MIflyer12 wrote:
    MohawkWeekend wrote:
    Not sure if this has been discussed previously or might be in the Technical Forum. Do the airlines track time from engine start to takeoff? Similarly from landing to shut down? Do they put a price on this? With the coming push to reduce aviation's greenhouse gas emissions, reducing these times would be IMO low hanging fruit.

    It would be interesting to see how major airports rank in this metric. (ORD vs ATL etc.)


    How do you think that carbon cost is going to compare to the costs of dozens of $80 million assets sitting there, waiting to take off? How do you think it will compare to fuel costs in the U.S.? If they could put planes in the air faster, they would.



    But do they? Does any major airport have a system that controls aircraft before they get in line to take-off? Surely a computer program can calculated taxi time from a gate to an active runway so that only 3 of 4 aircraft are in line at any one time. I assume currently everyone just pushes back and get in line. Example DCA and LGA as perhaps the worst.

    I wasn't looking for airport delays as the DOT tracks them but the metric of what airport is the most efficient in getting an aircraft in the air from engine start.
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      GalaxyFlyer
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      Re: Taxi and Delay Times

      Wed Mar 10, 2021 9:38 pm

      MohawkWeekend wrote:
      MIflyer12 wrote:
      MohawkWeekend wrote:
      Not sure if this has been discussed previously or might be in the Technical Forum. Do the airlines track time from engine start to takeoff? Similarly from landing to shut down? Do they put a price on this? With the coming push to reduce aviation's greenhouse gas emissions, reducing these times would be IMO low hanging fruit.

      It would be interesting to see how major airports rank in this metric. (ORD vs ATL etc.)


      How do you think that carbon cost is going to compare to the costs of dozens of $80 million assets sitting there, waiting to take off? How do you think it will compare to fuel costs in the U.S.? If they could put planes in the air faster, they would.



      But do they? Does any major airport have a system that controls aircraft before they get in line to take-off? Surely a computer program can calculated taxi time from a gate to an active runway so that only 3 of 4 aircraft are in line at any one time. I assume currently everyone just pushes back and get in line. Example DCA and LGA as perhaps the worst.

      I wasn't looking for airport delays as the DOT tracks them but the metric of what airport is the most efficient in getting an aircraft in the air from engine start.


      The crew has to get a clearance to push and taxi, if there’s a traffic delay, ATC delays the push and leaves them at the gate, IF that’s possible. Often the gate is needed for an inbound and the plane has to be off the gate. DCA and LGA are very cramped ramps, hence the long lines to go—they need the outbound off the gate.
       
      IAHFLYR
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      Re: Taxi and Delay Times

      Wed Mar 10, 2021 11:16 pm

      maps4ltd wrote:
      As for inbound taxis, ORD and DFW seem to have some of the longest. In particular 17L/35R at DFW and 9L/27R at ORD.


      Check out ATL when landing 10/28 or IAH when landing 8L/26R and they have to taxi through the east cargo ramp due to low weather conditions both vis and ceiling. I've been on an IAH landing flight on 26R and from the time we landed until we parked at B31 is was close to 20 minutes and that was non-stop at a pretty good taxi speed.
      Any views shared are strictly my own and do not a represent those of any former employer.
       
      MohawkWeekend
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      Re: Taxi and Delay Times

      Wed Mar 10, 2021 11:24 pm

      Good points GalaxyFlyer.

      Getting back to my original question - I was just wondering if an airline say United for example knows that the avg taxi time at DEN is xx minutes and ORD is XX+. Is that information available or is it proprietary? I would imagine the FAA could use it for planning purposes. A.NET readers like myself are just interested.

      Still recall the story (or is it a myth?) about an Eastern pilot who returned to the gate in ATL and retired due to the frustration of waiting in line to take off.
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        Flow2706
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        Re: Taxi and Delay Times

        Thu Mar 11, 2021 12:17 am

        VSMUT wrote:
        Low hanging fruit, maybe. It is better to wait on the ground than in the air over the destination. Eurocontrol does a pretty good job at slotting aircraft so the wait is at the runway and not in a holding pattern at the destination.

        If there is a slot the aircraft usually won't get a pushback clearance until a reasonable time before CTOT. This is the concept of TSAT - if there is a CTOT issued by CFMU/Eurocontrol there will also be a TSAT and therefore the aircraft will wait at gate with engines off and not near the runway with engines running.
         
        MohawkWeekend
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        Re: Taxi and Delay Times

        Thu Mar 11, 2021 12:44 am

        Traffic flow including reducing wasted "time in line" in the air and ground with engines running will be the low hanging fruit for CO2 reductions - esp compared to bio fuel mandates

        Now someone needs to perfect the robotic electric tug to take the aircraft to the runway and then back to the gate.
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          GalaxyFlyer
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          Re: Taxi and Delay Times

          Thu Mar 11, 2021 1:09 am

          Flow2706 wrote:
          VSMUT wrote:
          Low hanging fruit, maybe. It is better to wait on the ground than in the air over the destination. Eurocontrol does a pretty good job at slotting aircraft so the wait is at the runway and not in a holding pattern at the destination.

          If there is a slot the aircraft usually won't get a pushback clearance until a reasonable time before CTOT. This is the concept of TSAT - if there is a CTOT issued by CFMU/Eurocontrol there will also be a TSAT and therefore the aircraft will wait at gate with engines off and not near the runway with engines running.


          None of which happens in the US, well mostly not. We do sometimes have CTOT “wheels up” times.
           
          GalaxyFlyer
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          Re: Taxi and Delay Times

          Thu Mar 11, 2021 1:10 am

          MohawkWeekend wrote:
          Traffic flow including reducing wasted "time in line" in the air and ground with engines running will be the low hanging fruit for CO2 reductions - esp compared to bio fuel mandates

          Now someone needs to perfect the robotic electric tug to take the aircraft to the runway and then back to the gate.


          How are you going handle warm up and cool down times which as often as not are 50% of the taxi times. 3-5 minutes.
           
          ChrisKen
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          Re: Taxi and Delay Times

          Thu Mar 11, 2021 12:18 pm

          MohawkWeekend wrote:

          But do they? Does any major airport have a system that controls aircraft before they get in line to take-off? Surely a computer program can calculated taxi time from a gate to an active runway so that only 3 of 4 aircraft are in line at any one time. I assume currently everyone just pushes back and get in line. Example DCA and LGA as perhaps the worst.


          LHR has such a system. It also arranges the sequence to make optimal use of the runway capacity. eg, groups blocks of aircraft by weight category to minimise waiting around for WT separation times....etc etc.
           
          MohawkWeekend
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          Re: Taxi and Delay Times

          Thu Mar 11, 2021 1:27 pm

          GalaxyFlyer wrote:
          MohawkWeekend wrote:
          Traffic flow including reducing wasted "time in line" in the air and ground with engines running will be the low hanging fruit for CO2 reductions - esp compared to bio fuel mandates

          Now someone needs to perfect the robotic electric tug to take the aircraft to the runway and then back to the gate.


          How are you going handle warm up and cool down times which as often as not are 50% of the taxi times. 3-5 minutes.



          True - there would have to be some sequencing to allow for those 3 to 5 minutes if a electric tug were used. In the interim, it sounds like LHR system the previous poster listed could work now.

          In the next few years, electric powered ground support vehicles will have to be considered part of the industry contribution to reduce CO2. When I worked on the ramp, we'd leave diesel equipment running all night so it would be available for those 530 am pushbacks on frigid days.
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            MO11
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            Re: Taxi and Delay Times

            Thu Mar 11, 2021 3:54 pm

            MohawkWeekend wrote:


            True - there would have to be some sequencing to allow for those 3 to 5 minutes if a electric tug were used. In the interim, it sounds like LHR system the previous poster listed could work now.

            In the next few years, electric powered ground support vehicles will have to be considered part of the industry contribution to reduce CO2. When I worked on the ramp, we'd leave diesel equipment running all night so it would be available for those 530 am pushbacks on frigid days.



            This is much more complicated. Does the airport have multiple departure runways? Does it have dual taxiways to the departure runway(s)? If it has multiple runways, do you send the departure to the runway closest to the gate or to the runway that more closely aligned with the direction of departure. And in addition to controlled departure times, some airplanes may have expanded in-trail separation going into a given sector. And then if such a system is perfected, where do you stage these departures? Or do they block the alleyways and gates, requiring incoming aircraft to hold out somewhere?
             
            MohawkWeekend
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            Re: Taxi and Delay Times

            Thu Mar 11, 2021 10:19 pm

            It is complicated. I'm still try to figure out why traffic lights stay red when there is no cross traffic in sight.

            Wasn't there a recent implementation of optimized routing that will save fuel? That took years to implement (along with any ATC changes). However if the CO2 issue gets really serious, airlines are going to have to pull alot of rabbits out of the hat to reduce it's impact. You can pay alot of programmers if carbon free jet fuel is $8 gallon.
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              GalaxyFlyer
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              Re: Taxi and Delay Times

              Thu Mar 11, 2021 11:50 pm

              There’s no rabbits in the hat—transporting x number of passengers from Point A to Point B requires a certain amount of energy producing a carbon by-product. Physics and chemistry are pretty well studied sciences. Carbon-based fuels are it and will be for aviation for a long time.
               
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              AirKevin
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              Re: Taxi and Delay Times

              Thu Mar 11, 2021 11:59 pm

              MohawkWeekend wrote:
              It is complicated. I'm still try to figure out why traffic lights stay red when there is no cross traffic in sight.

              So if all traffic lights were green and you have two vehicles coming into the intersection from two different directions at the exact same time, do they run into each other because both have the green light. Or if the light turns red, who gets the red light.
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              Starlionblue
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              Re: Taxi and Delay Times

              Fri Mar 12, 2021 1:58 am

              AirKevin wrote:
              MohawkWeekend wrote:
              It is complicated. I'm still try to figure out why traffic lights stay red when there is no cross traffic in sight.

              So if all traffic lights were green and you have two vehicles coming into the intersection from two different directions at the exact same time, do they run into each other because both have the green light. Or if the light turns red, who gets the red light.


              Some places have sensors and logic that changes the light :)
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              dennypayne
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              Re: Taxi and Delay Times

              Fri Mar 12, 2021 2:23 am

              Starlionblue wrote:

              Some places have sensors and logic that changes the light :)


              I met the guy that has the patent on the system with the loop of wire that gets installed in the street to do that. He had a very nice house.

              My point being, there's a difference between having the capability of doing something in theory versus the practicality of actually paying for and implementing said system. Anything in aviation is going to start at a high dollar figure, and complexity such as all the runway permutations etc. etc. that have been mentioned are only going to increase the costs. I think it will take a lot more than $8/gal fuel to force those changes.
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              MohawkWeekend
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              Re: Taxi and Delay Times

              Fri Mar 12, 2021 3:40 am

              Airline CEO's were meeting recently with the Biden administration to figure out ways to subsidize low carbon fuels. No news was released about what was discussed.

              We haven't seen the new administration announce their new carbon policy - probably because the economy is still recovering. But when the economy does recover, this industry better be ready for some serious challenges. Remember they believe that climate change is the most significant security threat to the US.
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                CeddP
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                Re: Taxi and Delay Times

                Fri Mar 12, 2021 8:29 am

                Airlines already scrutinize all this. Back around 15 years ago and with the creation of the EU Emission Trading System, airlines had to start to monitor and report their exact fuel burn. A couple of software companies were then created to deal with this, like Aviaso, ETS Aviation, Osys etc... Most of them are now part of bigger groups (Honeywell, Boeing, Rolls Royce...) and use their expertise in fuel monitoring to also promote cost saving initiatives using all the data they crunch on a daily basis.

                Back to taxi and delay times, it's all recorded and monitored to the second. As an example, during my last flight out of JFK, I know that pushback and engines start took us 4 minutes 45 sec while we burned 91kgs of fuel, we then taxied for 11min 05sec without stopping until holding point where we waited 3min 56s. We burned 240kg during this 1,69NM taxi, with an average N1 of 18.92%. We have as much, if not more informations for the climb, cruise, descent, landing, taxi-in phases... And as just a regular pilot, I'm far from having access to all details. So when I say airlines are already scrutinizing this, I'm not making things up ! ;)

                What it allows us to do, from an operational standpoint, is to be as accurate as possible at the planning stage (mainly to decide on fuel load). It also helps in planning some of the cost saving practices like single engine taxi for example. As said earlier, there are lots of limitations (warm-up/cooling time, crossing of active runways, slopes...), these are all looked at by the software (see https://blog.openairlines.com/engine-out-taxi-in-eoti)
                 
                MohawkWeekend
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                Re: Taxi and Delay Times

                Fri Mar 12, 2021 12:55 pm

                CeddP - thanks for the interesting info. I'm assuming these times were recent - i.e. during COVID-19 traffic conditions. Would be interesting to know what the fuel burn would be in a lineup of 10 aircraft where every one shuffles forward and the delays are longer.

                So far from this discussion, it seems only European authorities (LHR was given as an example) are tying this type of data into ground operations to reduce time sitting in line with engines running. (Must be an American thing - every man (or plane ) for himself. We see it on our highways all the time too. ) My point in starting this tread was to discuss what thoughts this community had to find efficiencies for the reduction of CO2 (and saving money).

                Recently General Motors announced they would cease making internal combustion engines in passenger vehicles by 2030. Recently Southwest Airlines bought a couple hundred kerosene burners that with a 20 to 25 year life span will be operating until 2045. The airlines are betting the farm that carbon free fuels will be available. I realize they don't have much of a choice but improving system efficiencies with a program like LHR 's might be a first step.
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                  Woodreau
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                  Re: Taxi and Delay Times

                  Fri Mar 12, 2021 1:20 pm

                  JFK holds aircraft at the gate during peak traffic. I don’t know if it’s an airport thing or if it’s an airline thing... if you’re on the American ramp at T8 and you’re scheduled to push during the peak traffic, you call for push and ramp gives you an estimated push time and you get to hold on the gate until your push time.

                  The only other place I’ve seen this is ASE, ATC will hold you at the gate or the FBO ramp to relieve traffic congestion on the airport during busy weekends... It’s mainly to manage their one taxiway between inbound aircraft and outbound aircraft on the one-way in opposite way out single runway...

                  At my airline if a given flight is subject to ATC traffic metering, the SOC will direct operations to hold the boarding of passengers until it is closer to the ATC EDCT time instead of boarding to meet the scheduled departure time. That way taxi time is kept to a minimum and we don’t encounter having to return to the gate due to the FAA tarmac delay rule.
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