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The Classroom (Controller Tips) / Review: "One In One Out Rule" at Class D Airports
« on: April 28, 2015, 01:56:36 PM »
This rule is the most restrictive and conservative method of IFR separation by a radar facility overhead a Class D facility.
That being said, let this serve as a reminder of how IFR operations work at Class D airports:
Class D control towers can separate IFR operations within their airspace by visual separation as long as standard IFR separation exists prior to and after the application of visual separation.
However, in real life Letters of Agreement are sometimes much more restrictive than this based on what type of facility overlies the airport and what radar equipment is in use by them. Because of this, the rest is a review of the most restrictive/conservative method of IFR separation in the Class D tower environment.
Class D towers must report to the radar facility overhead (i.e. DEN_APP when working APA_TWR) when an IFR arrival lands.
- Ex. "Denver Approach, Centennial Tower." "Denver Approach." "N123 has landed." "ZY" "MM"
This tells the radar facility that they may clear the next IFR arrival for approach into the airport, or issue a departure release to an IFR departure who is waiting.
That is also why we must obtain an IFR release for all IFR departures. Ex. "Denver Approach, Centennial Tower." "Denver Approach." "Request release N123 to Grand Junction." (Include the runway number if more than one is in use at your airport as advised to the radar facility and within the ATIS). "N123 is released." "JW" "DM" (The release may include a heading to fly, or an amended initial altitude. If not, it is the tower's discretion to assign a heading if a pilot nav SID is not being flown).
If the radar facility has an IFR arrival inbound that is established on an Instrument Approach Procedure (IAP) they may issue "N123, hold for release" or "N123, expect departure clearance 0130 Zulu". It is the radar facility's job to call the tower back to issue the release when able; generally when the tower calls to advise the previous IFR arrival has landed.
Tower provided visual separation:
- If the radar facility sees fit, based on the weather and traffic situation, they can delegate responsibility for utilizing visual separation between two specific IFR operations to the tower. Ex. "Visual separation approved between N123 and N456, N456 released at your discretion."
Voila! Advise if you have questions.
ZY
That being said, let this serve as a reminder of how IFR operations work at Class D airports:
Class D control towers can separate IFR operations within their airspace by visual separation as long as standard IFR separation exists prior to and after the application of visual separation.
However, in real life Letters of Agreement are sometimes much more restrictive than this based on what type of facility overlies the airport and what radar equipment is in use by them. Because of this, the rest is a review of the most restrictive/conservative method of IFR separation in the Class D tower environment.
Class D towers must report to the radar facility overhead (i.e. DEN_APP when working APA_TWR) when an IFR arrival lands.
- Ex. "Denver Approach, Centennial Tower." "Denver Approach." "N123 has landed." "ZY" "MM"
This tells the radar facility that they may clear the next IFR arrival for approach into the airport, or issue a departure release to an IFR departure who is waiting.
That is also why we must obtain an IFR release for all IFR departures. Ex. "Denver Approach, Centennial Tower." "Denver Approach." "Request release N123 to Grand Junction." (Include the runway number if more than one is in use at your airport as advised to the radar facility and within the ATIS). "N123 is released." "JW" "DM" (The release may include a heading to fly, or an amended initial altitude. If not, it is the tower's discretion to assign a heading if a pilot nav SID is not being flown).
If the radar facility has an IFR arrival inbound that is established on an Instrument Approach Procedure (IAP) they may issue "N123, hold for release" or "N123, expect departure clearance 0130 Zulu". It is the radar facility's job to call the tower back to issue the release when able; generally when the tower calls to advise the previous IFR arrival has landed.
Tower provided visual separation:
- If the radar facility sees fit, based on the weather and traffic situation, they can delegate responsibility for utilizing visual separation between two specific IFR operations to the tower. Ex. "Visual separation approved between N123 and N456, N456 released at your discretion."
Voila! Advise if you have questions.
ZY