ASPM Taxi Times: Definitions of Variables

The following definitions define the fields in the ASPM reports of Taxi Times:

• Actual Gate Out. The time an aircraft departed from the gate. Gate Out times are provided for many carriers by ASQP, ARINC, and TFMS, and is estimated for all other flights. See ASPM: Estimation Techniques.
• Actual Wheels Off. The time an aircraft takes off. Wheels Off times are provided for most flights from ASQP, ARINC, TFMS, or CountOps. It is estimated from the DZ message for all other flights. See ASPM: Estimation Techniques.
• Airport. The three- or four-letter code identifying the airport.
• Arrival Airport. The three- or four-letter code identifying the airport of arrival.
• 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.
• 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.
• 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 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.
• Arrivals With Taxi In Time, Minutes (<15, 15–29, 30–44, 45–59, 60–74, ≥75, ≥30, ≥30(%). The number and percentage of arrivals with the specified Wheels On to Gate In duration.
• Average Taxi In Time. The average difference between Actual Gate In time and Actual Wheels On time, in minutes. Taxi in time is observed for flights for which OOOI data are available, otherwise it is estimated.
• Average Taxi Out Time. The average difference between Actual Wheels Off time and Actual Gate Out time, in minutes. Taxi out time is observed for flights for which OOOI data are available, otherwise it is estimated.
• Carrier. The three-letter code identifying the carrier.
• Carrier Code. The three-letter code identifying the carrier.
• Count of Departures. Total number of departures per selected criteria.
• Departure Airport. The three- or four-letter code identifying the departure airport.
• 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.
• 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.
• 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 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, 20-39, 40-59, 60-119, 120-179, ≥180, ≥40, ≥40(%), <40, ≥90, ≥60, ≥60(%), ≥90). The number and percentage of departures with the specified Gate Push Back to Wheels Off duration.
• EDCT Wheels Off. The runway release time assigned based on Expect Departure Clearance Time (EDCT).
• Equipment. This is usually a three- or four-character field extracted from an TFMS flight plan or from an available ASQP record.
• ETMS. 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 (or Flight Number). The number identifying the flight as assigned by the air carrier. Permissible values: 1–9999.
• 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).
• 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 TFMS 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 TFMS 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.
• OAG. A record marked Y (YES) indicates that the flight record was constructed utilizing an OAG record.
• 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, ARINC, or TFMS record was used to construct the ASPM record.
• OOOI Present. This variable is marked Y (YES) or N (NO). It indicates whether actual OOOI data contained in an ASQP, ARINC, or TFMS record was used to construct the ASPM record. When N, Actual Gate Out, Actual Wheels Off, Actual Wheels On, and Actual Gate In times are estimated. See ASPM: Estimation Techniques.
• Scheduled Departure Date. Scheduled Departure Date observed using local clock time at a particular location.
• Scheduled Gate Out. Scheduled Gate Out from the schedule or ASQP, when available, otherwise is set to the TFMS Flight Plan Filed PTime.
• 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.
  • Taxi In Time Median: The median of the Taxi In Time (Actual Gate In minus Actual Wheels On) for arrivals in this time period.
• Taxi In. The difference between the Wheels On time and Gate In time, 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 Out Time (Unimpeded, Average, Median, 10th Percentile).
  • Unimpeded Taxi Out Time: The estimated Taxi Out 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 and season for each carrier and airport reporting OOOI data.
  • 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 Wheels Off time and Gate Out time, in minutes.
• User Class. Air Carrier, Freight, Air Taxi, General Aviation, and Military. User classes are designations assigned by the Volpe Center based on the equipment reported.