Ghosts of O'Hare

[Cyclic Hotline]

Hi all. Don't have much call to come into this realm. Saw this today and thought it might interest some of you.

O'Hare Controllers See Ghost Planes

CHICAGO (AP) - False radar images have been popping up on the screens of O'Hare International Airport's air traffic controllers, forcing pilots to take sudden turns unnecessarily, the Chicago Sun-Times reported in its Sunday editions.

At least a dozen "ghost planes'' have been reported during the last few weeks, the newspaper said, citing documents from the Terminal Radar Approach Control center in Elgin, Ill., and interviews with controllers.

Controllers said that at least a few times, they have ordered pilots to take sudden turns to avoid what appeared to be planes on their radar, potentially putting passengers at risk.

"The ghosting is a complete terror for the air traffic controllers,'' said Charles Bunting, president of the Elgin local of the National Air Traffic Controllers Association.

False radar images can appear when a crane or construction tower is put up, said Federal Aviation Administration spokesman Tony Molinaro. Planes from nearby airports also have appeared much closer to O'Hare than they actually were in recent weeks, controllers said.

Molinaro said there have been 13 ghost images in the last five weeks, rather than the eight or nine the FAA would usually expect in that time period, "meaning we still need to look into them.''

But Mike Egan, vice president of the controllers union at Elgin, accused the FAA of playing down the problem. "Maybe 130, but not 13,'' Egan said Friday. "We had a couple of them today, as a matter of fact. ... They know there's a problem.''

O'Hare controllers have also recently complained about the FAA's plans to speed air traffic at O'Hare by stacking arriving planes vertically around O'Hare's air space rather than having them line up single-file.

Bunting said the radar situation raises questions about the safety of the procedure.

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[Self Loading Freight]

'Ere, I thought that ground reflections never made it to the displays because they don't move -- no doppler, no show. At least, that's what I was told when I was shown around a radar factory.

I do know that radio conditions are reasonably messy at the moment, and you can get anomalous propagation that increases clutter and false returns. Perhaps it's something to do with the sunspot peak and associated events...

Does the 50cm radar at LHR suffer from this particularly?

R

[cleared2land 27left]

Not that im aware of but the SMR is crap, especially in low vis.

[Bagheera]

Self loading,
you are quite right in that permanent echos ie ground based objects should not show unless you wish them too....however I recall working Wallesy sector (Pole Hill) one day ,when we got horrendous ghost images and were giving aircraft avoiding actions on themselves....When engineers went to the radar station they found the bosses son inside the compound parked next to the radar head making out with his girlfriend!....the metal of the car was reflecting energy into the radar head and throwing the time scope out of sync hence two returns!

[Captain Airclues]

Before the airport was renamed O'Hare, it was called Orchard Field (hence the ORD). The airport authorities recently pulled down the last of the old 1930s hangars. Perhaps the images are the ghosts of the aircraft that used to inhabit these hangars, looking for new homes. :)

Airclues

[NudgingSteel]

Cyclic....cheers for that, it's an interesting article. Come and visit our section more often!

Captain Airclues...and thank you too, I never worked out the KORD designator and whilst training, used to try to clear people to Orlando instead. Still they were very polite about correcting me.

Bagheera...your post just goes to prove that any sort of penetration of a controlled zone can affect ATC.....

[monopulse]

Since I work on the same terminal radar type as the one located at O'Hare (ASR-9), I find it hard to believe that this is anything more than operator error.

The controllers at the Tracon are working with "clean" scopes when viewing ASR-9 video meaning no grass level(noise). The ridiculous amount of processing within the ASR-9 filters out all non-moving returns period unless operators have chosen to deviate from the standard settings at their PPI. This processing time is significant enough to lag the digitized video being displayed to operators by roughly a full sweep of the antenna. Controllers don't see actual radar returns in real-time...its synthetic and delayed before it hits their displays.

The next generation of terminal radars (http://www.faa.gov/and/and400/AND440/ASR11/Public/Map/map.cfm) are now being installed which replaces older systems including the ASR-9 at O'Hare. With even better target processing in the latest versions of radar, O'Hare's ghost targets should disappear.

[This message has been edited by monopulse (edited 26 May 2000).]