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The Terminal Arrival Efficiency Rate (TAER) measures the arrival efficiency of flights from 100 miles out to Wheels On for a given time period. It is calculated by dividing the actual number of arrivals by the lesser of the facility set arrival rate or the number of demand units and is reported as a percentage not to exceed 100. The facility set arrival rate is the maximum rate that the airport can safely handle given the current conditions. For this reason, the airport’s TAER score is not penalized when demand exceeds the facility set arrival rate.

For more information about TAER metrics, see Terminal Arrival Efficiency Rate (TAER) 101: Metric Explanation.


The TAER was originally designed to measure TRACON performance and the impact of Traffic Management Initiatives (TMI) within 100 miles of the airport. This is not just a measure of the approach control performance: the ability of ARTCCs to deliver traffic evenly also impacts this measure.

What can cause a low TAER?

  • holding within 100 miles of the airport
  • offloading from one arrival fix to another within 100 miles
  • deviating around weather
  • vectoring or speed control for spacing
  • incorrect runway configurations entered into Operational Information System (OIS)

Data Sources for Calculation


Each day, input data are received by 0500 for the previous GMT-day completed flights from the following sources:

  • TFMS: Individual flight data (carrier, flight number, departure and arrival airport, DZ and AZ times, EDCT, ETE, and OOOI times for select carriers).
  • ARINC: Supplemental next-day data including Out, Off, On, In times (carrier, flight number, departure and arrival airport, OOOItimes).
  • Circle File: The 100- and 40-mile circle points are identified by the NAS Data Warehouse using RADAR data reported in TFMS (including the TRACON off-load data) on a flight by flight basis. These data are also used to determine the 40-mile standard crossing points for each airport (carrier, flight number, departure and arrival airport, latitude and longitude and time at 100 and 40 miles from arrival airport).
  • Runway File: Provides information about the runway configurations and arrival and departure rates (runway configurations, AAR, ADR, actual arrivals and departures by the hour).


  • TFMS: TFMS files are updated every 5 and 30 days to fill in missing or incorrect records in the next day files.
  • Airline Service Quality Performance (ASQP): Approximately 25 days after the end of the month, ASQP data files are received for the ASQP carriers (see ASQP: Carrier Codes and Names). At that time, ASPM records are updated/modified with new or revised flight information from ASQP records, including OOOI and flight schedule data.


  • Compute Start of Demand based on Estimated Wheels On Time by quarter hour.
  • Compute End of Demand based on Actual Wheels On Time by quarter hour.
  • For each quarter hour, calculate number of demand units and the number of actual arrivals.
  • Sum quarterly demand units and quarterly actual arrivals to obtain hourly counts.
  • TAER = Actual arrivals / (Arrival Demand not to exceed AAR)

Note: TAER cannot exceed 100.

Calculation of Estimated Wheels-On Time and Demand Units

The actual approach time from 100 miles out to Wheels On is compared to the estimated time. If the flight lands within the expected quarter hour, one demand unit is assigned. Each additional quarter hour results in an additional unit of demand for that flight.

Start of Demand = 100-mile Crossing Time + Estimated Time from the 100-mile circle to the 40-mile circle + Estimated Time from the 40-mile circle to Wheels On.

The calculation of the Estimated Wheels-On time uses a five-factor lookup table based on flights observed over the previous twelve months to select 1) the average speed from the 100-mile circle to the 40-mile circle for the 20% of flights with the most direct route (shortest distance) from the 100 to the 40; and 2) the average number of seconds from the 40-mile circle to wheels-on for the 20% of flights with the most direct route (shortest distance) from the 40-mile crossing point to wheels-on.

The five factors used to select the means are:

  1. Facility-Reported Runway Configuration
  2. Approach angle of aircraft at the 40 mile circle
  3. Weather Conditions (IMC or VMC)
  4. Weight of the aircraft
  5. Engine Type (Piston, Jet, Turbine)

For each flight, the estimated duration from 100 miles to 40 is calculated based on the mean speed and the distance from the 100-mile crossing point to the closest 40-mile crossing point (as determined by historical analysis of airport-specific routing). The estimated duration from 40 miles to wheels-on is based on the historical observations in the means table. These two airborne estimates are added to the 100-mile crossing time to give the estimated Wheels-On Time (Start of Demand).

A flight with up to 6 minutes of delay (difference between estimated and actual wheels-on time) will not be assigned additional units of demand. From 7 to 15 minutes of delay, the flight becomes increasingly at risk of being assigned more units of demand. Sixteen to 30 minutes of delay will correspond to 2 units of demand; 31 to 45 minutes correspond to 3 units; etc. Adjustments are applied to reduce the effect of quarter-hour grouping for the first unit of demand. Any delay or holding outside the 100-mile boundary does not affect the TAER score, but once the flight proceeds across the 100-mile boundary, the expectation clock starts.

The TAER score is reported by hour and rolled up for larger periods.

Data Exceptions

  • If no circle record exists for a TFMS record (about 20% on next day and about 2% on next day plus one day), then Start of Demand is Wheels Off plus ETE, and End of Demand is Wheels-On (same as SAER).
  • If the flight is less than 100 miles long, then the TAER is calculated from the 40-mile crossing.
  • If no weather data exists, then VMC values are used.
  • If no equipment match exists, then turbine is used.
  • If a five-factor match is not found in the means table, then default values of the overall average at the specific 40-mile approach angle (overall factors) are applied.

ASPM Modules Reporting on TAER Metric

TAER metric is reported on in the following ASPM modules and reports: