Deal or no deal?

Brian Pryor

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Deal or no deal?
« on: December 03, 2009, 02:29:15 PM »
http://www.thedenverchannel.com/news/21786985/detail.html

DENVER -- The CALL7 Investigators have confirmed the FAA is investigating a Nov. 23rd incident where two passenger jets nearly collided in the airspace over Colorado.

Sources told CALL7 Investigator John Ferrugia the two planes merged on Air Traffic Control radar at the same altitude and in the same moment.

Said one source, "They were within a blink of an eye of colliding," and "It was the ugliest thing I've ever seen in all my years."

More:
http://www.thedenverchannel.com/news/21786985/detail.html
Brian Pryor

Brad Littlejohn

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Deal or no deal?
« Reply #1 on: December 03, 2009, 04:07:32 PM »
If Fergus is right, then this is definitely a deal. Loss of vertical and horizontal separation. The crossing restriction at SAYGE would still be in Class A airspace, so the horizontal separation was lost by 1000ft. The question that needs to be asked is if the RPA arrival was asked to descend any further on his arrival to KDEN. Assuming that he already passed SAYGE, altitude/speed would need to be coordinated with D50. If he went back to SAYGE and was still under ZDV control, he would have to be at least at FL190, putting them head on with the SKW arrival.

The TRACON is in the clear on this, so it definitely is a deal for the ZDV controller.

BL.

Harold Rutila

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Deal or no deal?
« Reply #2 on: December 03, 2009, 10:31:14 PM »
Quote from: Brad Littlejohn
If Fergus is right, then this is definitely a deal. Loss of vertical and horizontal separation. The crossing restriction at SAYGE would still be in Class A airspace, so the horizontal separation was lost by 1000ft. The question that needs to be asked is if the RPA arrival was asked to descend any further on his arrival to KDEN. Assuming that he already passed SAYGE, altitude/speed would need to be coordinated with D50. If he went back to SAYGE and was still under ZDV control, he would have to be at least at FL190, putting them head on with the SKW arrival.

The TRACON is in the clear on this, so it definitely is a deal for the ZDV controller.

BL.
Yeah, it was a deal. Thank God for TCAS. All D01 (Denver TRACON) arrivals are usually told to descend at pilots' discretion to the altitude restriction, in this case being FL190. The article states that the controller was "apparently thinking the pilots would simply merge with the traffic already on the (SAYGE Six Arrival) sources said," which I don't really think is true unless the controller was absolutely not thinking straight...I mean, FL190 is still IFR-only airspace; planes aren't going to follow each other on STAR routes.

(The following is purely my own speculation:) I would guess that the ZDV controller was probably thinking he could put the Republic aircraft on the LANDR5, which runs adjacently to the SAYGE6. However, D01 recently restricted the use of LANDR (I'm not sure if that restriction is still in effect, but I believe it is) due to a lack of experienced controllers on D01's staff to handle parallel STAR traffic. The ZDV controller might have forgotten that in the high-traffic situation. It sounds to me as if RPA may have been inside or very close to the D01 TRACON boundary (perhaps a handoff was rejected?) but vectored north to SAYGE by Denver Center at the last minute due to the LANDR STAR closure. It's hard to say whether or not my theory is correct based on the FlightAware track for the Republic airplane because I can't tell where LANDR is in relation to SAYGE on their map, but I wouldn't be surprised if what I said is close to correct.

Brad Littlejohn

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Deal or no deal?
« Reply #3 on: December 04, 2009, 06:15:12 PM »
Someone correct me if I'm wrong. There is a nice conversation that I am involved in over at FlightAware that someone posted a map of the area on.

The way I'm seeing it, I see 3 deals:
  • Loss of horizontal separation between RPA and SKW.
  • Loss of vertical separation between RPA and SKW.
  • Loss of vertical separation between RPA and FFT.

This definitely earns the controller some retraining.

BL.