Automatic Dependent Surveillance-Broadcast in Retrofit Spacing trial

Albuquerque Air route traffic control center

CURRENTLY until november 7, 2024

Albuquerque Air Route Traffic Control Center (ZAB) has been conducting a trial for Automatic Dependent Surveillance-Broadcast (ADS-B) In Retrofit Spacing (AIRS) since November 7, 2022. The trial is specific to American Airlines (AAL) A321 and A321N aircraft landing KPHX on the EAGUL arrival. AAL A321s and A321Ns may space themselves behind a lead aircraft with ADS-B Out using avionics-command speed control after controller-specified in trail spacing is issued. This is known as Initial-Interval Management (I-IM).

Air Traffic Control instructions will include non-participating aircraft callsigns while an Air Traffic Clearance is being issued to participating aircraft. No action is to be taken by non-participating aircraft during these trials.

ADS-B In Retrofit Spacing (AIRS) procedures at zab

1. IM aircraft will be identified as AAL aircraft with A321 or A21N aircraft type designator. For the duration of the trial period, A321s and A21Ns will be the only IM equipped and capable aircraft. These aircraft are equipped with ADS-B In and Out avionics.
2. IM procedures are defined for ZAB controllers and qualified aircrews to utilize avionic command speeds to conduct operations within ZAB airspace. This operation allows flight crews to accept speed commands from the IM avionics to achieve controller issued Assigned Spacing Goals (ASG).
   1. Requirements for operating IM in ZAB airspace:
      1. IM for PHX arrivals is limited to the EAGUL arrival.
      2. IM clearance types:
         1. Cross Clearance – for aircraft en route to a common fix that will continue on the same route after the Crossing Point.
            Examples:
            “AAL755 cross (waypoint) at and maintain eight miles behind UAL345”
            “AAL755 cross (waypoint) at and maintain eighty-two seconds behind UAL345”
         2. Maintain Clearance – For aircraft already on the same route.
            Examples:
            “AAL755 maintain eight miles behind UAL345”
            “AAL755 maintain eighty-two seconds behind UAL345”
      3. The flight crew of the Trail aircraft will check on frequency and advise they are spacing behind the Lead aircraft.
         Example:
         “AAL457 checking on FL330 spacing behind UAL587”
         “AAL755, FL360, spacing behind UAL435”
      4. IM clearances are cancelled by a speed assignment or instruction.
         Examples:
         “AAL123 cancel spacing (optional), maintain Mach .73”
         “AAL123 descend via EAGUL six arrival runway 26 transition”
         “AAL123 resume normal/published speed”
         

ZAB [Updated 11/17/2023])