APM Taxi Times: Definition of Variables

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The following definitions define the fields in APM Taxi Times reports:


  • Airport. The three- or four-letter code identifying the airport.
  • Arrival Gap Time Count. The count of flights with a reported Wheels On time and AZ message time.
  • Arrival Gap Time Median. The median difference between the reported Wheels On time and the AZ message time in minutes.
  • Arrival Taxi In Count. The number of flights reporting a Wheels On and Gate In time required for calculating median Taxi In Times.
  • Arrival Taxi In Median. The median of the Taxi In Time (Actual Gate In minus Actual Wheels On) for arrivals in this time period, in minutes.
  • Arrivals for Metric Computation. Flight arrivals used for calculating metrics in ASPM. Only flight records that meet the following criteria are included: itinerant flights to or from one of the ASPM 77 Airports or operated by one of the ASPM Carriers (currently 29) with actual arrival and departure and flight plan times that are reported or can be estimated from the other flight record data. General aviation and military flights are excluded. Arrivals for Metric Computation are aggregated based on the scheduled arrival time if available, otherwise the flight plan arrival time is used.
  • Average Taxi In Time. The average of the Taxi In Times (Actual Gate In minus Actual Wheels On) in a specified time period, expressed in minutes.
  • Average Taxi Out Time. The difference between Actual Gate Out time and Actual Wheels Off time, in minutes. Taxi out time is observed for flights for which OOOI data are available, otherwise it is estimated.
  • Carrier Code. The three-letter code identifying the carrier.
  • Carrier. The three-letter code identifying the carrier.
  • Departure Gap Time Count. The count of flights with a reported Wheels Off time and DZ message time.
  • Departure Gap Time Median. The median difference between the reported Wheels Off time and the DZ message time, in minutes.
  • Departure Taxi Out Count. The number of flights with a reported Gate Out and Wheels Off time required for calculating median Taxi Out Times.
  • Departure Taxi Out Median. The median of the Taxi Out Time (Actual Wheels Off minus Actual Gate Out) for departures in a specified time period, expressed in minutes.
  • Departures For Metric Computation. Flight departures used for calculating metrics in ASPM. Only flight records that meet the following criteria are included: itinerant flights to or from one of the ASPM 77 Airports or operated by one of the ASPM Carriers (currently 29) with actual arrival and departure and flight plan times that are reported or can be estimated from the other flight record data. General aviation and military flights are excluded. Departures for Metric Computation are aggregated based on the scheduled departure time if available, otherwise the flight plan departure time is used.
  • Departures With Taxi Out Time, Minutes (20-39, 40-59, 60-119, 120-179, ≥180, ≥40, ≥40(%), <40, ≥90, ≥60, ≥60(%). The number and percentage of departures with the specified Gate Push Back to Wheels Off duration.
  • Equipment. This is usually a three- or four-character field extracted from an ETMS flight plan or from an available ASQP record.
  • ETMS. Variable indicating whether the APM record was constructed utilizing an ETMS record. A record marked Y (YES) indicates that the flight record was constructed utilizing an ETMS record, which is the source for some or all flight plan data (gate departure, ETE), and DZ and AZ data. If an ETMS record was not used, then flight plan times and DZ and AZ times are estimated.
  • Flight Type. Filter option indicating flight direction. Permitted variables are: Domestic (both arrival and departure are in the US), US to Foreign, Foreign to US, and Foreign (both arrival and departure are in a foreign country).
  • Flight. The number identifying the flight as assigned by the air carrier. Permissible values: 1–9999.
  • Gap AZ. The difference between Wheels On Time and AZ message time, generally ranging from 1 minute to 10 minutes. This value is measured when both ETMS Present = Y and OOOI Present = Y. Observed values are used to calculate the median times (by day, by airport, by hour) for estimation of the Wheels On times in records for which it is not reported.
  • Gap DZ. The difference between DZ message time and Wheels Off time, generally about 1 minute. This time is measured when both ETMS Present = Y and OOOI Present = Y. Observed values are used to calculate the median times (by day, by airport, by hour) for estimation of the Wheels Off Times in records for which it is not reported.
  • Local Hour. Used to determine the time when an event occurred or was scheduled at a facility, not as a Universal Time Coordinate (UTC) or (GMT). Scheduled Local hour used in metric calculations is based on Scheduled Gate Out or Scheduled Gate In time. Local hour used in efficiency calculations is based on Wheels Off or Wheels On time.
  • OOOI Arrival Time. Actual Wheels On Time.
  • OOOI Departure Time. Actual Gate Out Time of departure.
  • OOOI. Variable indicating whether actual OOOI data contained in an ASQP or ARINC record was used to construct the APM record.
  • Scheduled Departure Date. Scheduled Departure Date observed using local clock time at a particular location.
  • Season. Unimpeded Taxi In and Unimpeded Taxi Out times are computed by Season: 1 for Winter (December to February), 2 for Spring (March to May), 3 for Summer (June to August), 4 for Fall (September to November), and 0 for weighted average 12 months.
  • Taxi In Time (Unimpeded, Average, Median, 10th Percentile).
    • Unimpeded Taxi In Time: The estimated Taxi In Time for an aircraft by carrier under optimal operating conditions (when congestion, weather, or other delay factors are not significant). This number is estimated by calendar year for each carrier and airport based on observed values in the previous year.
    • Average Taxi In Time: The average of the Taxi In Times (Actual Gate In minus Actual Wheels On) in a specified time period.
    • Taxi In Time Median: The median of the Taxi In Time (Actual Gate In minus Actual Wheels On) for arrivals in this time period, in minutes.
    • Taxi In Time 10th Percentile: The 10th percent of the distribution for Taxi In Time for arrivals in this time period. Ten percent of the observed Taxi In Times are equal to or less than this value.
  • Taxi In. The difference between the Wheels On time and Gate In time, in minutes.
  • Taxi Out Time (Unimpeded, Average, Median, 10th Percentile).
    • Unimpeded Taxi Out Time: The estimated Taxi Out Time (in minutes) under optimal operating conditions (when congestion, weather, or other delay factors are not significant). This number is estimated by calendar year and season for each carrier and airport reporting ASQP and ARINC data.
    • Average Taxi Out Time: The difference between Actual Gate Out time and Actual Wheels Off time, in minutes. Taxi out time is observed for flights for which OOOI data are available, otherwise it is estimated.
    • Taxi Out Time Median: The median of the Taxi Out Time (Actual Wheels Off minus Actual Gate Out) for departures in a specified time period.
    • Taxi Out Time 10th Percentile: The 10th percent of the distribution for Taxi Out Time for departures in this time period. Ten percent of the observed Taxi Out Times are equal to or less than this value.
  • Taxi Out. The difference between the Gate Out time and Wheels Off time, in minutes.
  • Total Taxi In Time. Total sum of Taxi In Time for arrivals in a specified time period.
  • Total Taxi Out Time. Total sum of Taxi Out Time (Actual Wheels Off minus Actual Gate Out) for departures in a specified time period.
  • User Class. Air Carrier, Freight, Air Taxi, General Aviation, Military, and Other. User classes are designations assigned by the Volpe Center based on the equipment reported.