Mr Spaceman
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ILS Calibrating With An Airborne Laser?

Sun Jul 04, 2004 1:41 am

Hi guys.

In these 2 photos of a Beech Super King Air 200 the photographer explains that the aircraft is ............

"Used for checking and calibrating the ILS system and airport lighting."


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Photo © Daniel Alaerts - AirTeamImages
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Photo © Derek Pedley - AirTeamImages



In this photo below, the photographer explains that the man under the King Air is cleaning the laser which can be seen hanging down from the belly behind the nosegear doors.

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Photo © Dimitris - AirTeamImages



My questions are:

How is the laser on the King Air used to check and calibrate the ILS system for a runway or it's lighting system? (I'm assuming it's the approach lighting & rwy threshold & touchdown zone lighting that's being checked).

When I think of a laser, I think of a laser beam that's aimed at something.

In the case of an ILS system being calibrated, what would the laser beam be pointed at? Is there a ground crew involved in the test that has equipment set up in the middle of the runway's touchdown zone that the aircraft's laser is aimed at while on the proper glideslope angle ....... perhaps?

I simply curious about this. Big grin


Chris  Smile

"Just a minute while I re-invent myself"
 
Contact_tower
Posts: 534
Joined: Mon Sep 17, 2001 4:05 am

RE: ILS Calibrating With An Airborne Laser?

Sun Jul 04, 2004 2:24 am

It's not a laser, the laser in placed on the ground. What the guy is cleaning is the reflector for the laser system.

When you calibrate the Papi and ILS GP, a ground crew riggs the system beside the runway at TDZ.

As far as I know, you don't need this system to check approach lights etc, only Papi/Vasis/Plasi and ILS Glidslope and LLZ.

Calibartion of Navaids and lights involves quite a lot of different flight patterns, but it covers 4 A4 pages in our manual, and is frankly a bit to much to go in detail here.
 
Mr Spaceman
Topic Author
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Joined: Thu Mar 15, 2001 5:09 am

RE: ILS Calibrating With An Airborne Laser?

Sun Jul 04, 2004 4:04 am

Hello Contact tower.

Thank You, for your reply.

OK, so the white object on the aircraft's belly isn't a laser, it's actually a reflector for a laser that's positioned on the ground beside a runway's touchdown zone by a crew of technicians.

The caption under the photo with the guy crawling under the King Air says he was under there to "clean the laser" so I guess the photographer had the right idea ........... but just not perfect info. But then, who's perfect? Big grin

I understand that it's only the PAPI & VASIS lights that are tested (I don't remember what PLASI stands for), and not the approach lights. That makes more sense.

I appreciate your explanation of how an airborne reflector and ground based laser are set up to perform these calibrations. I understand that the exact details of these tests would be a bit to much to go into detail about.

Thanks Again,

Chris  Smile
"Just a minute while I re-invent myself"
 
QantasA332
Posts: 1473
Joined: Sat Dec 13, 2003 5:47 pm

RE: ILS Calibrating With An Airborne Laser?

Sun Jul 04, 2004 7:23 am

The laser reflector is referred to colloquially as the 'brick,' and it consists of a number or prisms which give the ground-based laser something to lock onto. While the aircraft's GPS can give the position of the aircraft to within 8 feet, something more accurate is needed -- hence the ground-based laser, which calculates the plane's location to within about 6 inches. That position is compared to the position of the glideslope and localizer, which is then used for various calibrations.

If you have access to it, the January 2003 issue of Air International has an extensive, very interesting article on Flight Precision Ltd. (the company using that system) and their work.

Cheers,
QantasA332
 
Mr Spaceman
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RE: ILS Calibrating With An Airborne Laser?

Sun Jul 04, 2004 12:32 pm

Hi guys.

>> QantasA332, Thank You Sir, for yor reply and excellent info.

You are obviously a very smart guy, and I enjoy learning from you. You definetly have a bright future ahead of you!  Big thumbs up

I used to read the Air International magazine all the time (and have a lot of issues in boxes), but I've run out of time on my daily clock to read everything that I wish I could.  Sad

It's amazing just how precise these tests can be, but then again, CAT IIIa ILS (or CAT II & CAT I) approaches need to be fine tuned for a safe landing to be capable.

I've seen a Challenger 601 bizjet like this one (with low vis markings) from NAV CANADA shooting many approaches to different runways at Toronto's Pearson International (YYZ). I wonder if that jet has extendable laser reflectors ("bricks")?


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Photo © John Davies
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Photo © John Davies




Chris  Smile
"Just a minute while I re-invent myself"
 
QantasA332
Posts: 1473
Joined: Sat Dec 13, 2003 5:47 pm

RE: ILS Calibrating With An Airborne Laser?

Sun Jul 04, 2004 1:18 pm

You are obviously a very smart guy, and I enjoy learning from you. You definetly have a bright future ahead of you!

Aww, shucks. Embarrassment  Laugh out loud Thanks for the very kind compliment!

As for Nav Canada, I dunno what exactly they do and if 'blocks' and* involved. Sorry.

Cheers,
QantasA332

* Edit: "are."

[Edited 2004-07-04 06:31:00]
 
Mr Spaceman
Topic Author
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RE: ILS Calibrating With An Airborne Laser?

Mon Jul 05, 2004 1:59 am

Hello QantasA332.

You're very welcome.

Trust me, a smart young man like yourself deserves a good pat on the back. It's a pleasure to know that guys like you are out there. Us older men who have more grey hair on our skulls then colour are always happy to know that there are pro's growing up in this world of airplanes.

Regarding the Canadian NAV CAN Challenger jet, I remember listening to my receiver back in the winter and hearing a NAV CAN pilot (who knows what type of aircraft), who was shooting approaches to Toronto's YYZ, and at one point during the communications between the pilot and Toronto ATC the pilot became very upset with the controller and transmited these kind of words ...........

"Toronto center, let me explain to you that I'm in control, tell your friends, tell your boss. "I" will let you know what heading, altitude and airspeed I need to fly on. I'm currently over WASSIE at four thousand three hundred feet on course to intercept the ILS for 23. Do you copy?"

I was shocked to hear this pilot talk to Toronto ATC this way, I thought it sounded rather rude, however, I don't know what the deal is when a specially equiped aircraft that's owned by the government is flying test approaches.

Maybe the ATC controllers are supposed to be well aware of their (the pilot's), activities and need to vector other aircraft away from the test aircraft.

I just know that I've never heard a pilot be so stern with a controller before. It caused an uncomfortable feeling for me (as a listener), but, I also understand that somebody needs to put their foot down and explain who's in charge when it's nessesary.

Just some useless info my friend. Big grin

Chris  Smile
"Just a minute while I re-invent myself"
 
QantasA332
Posts: 1473
Joined: Sat Dec 13, 2003 5:47 pm

RE: ILS Calibrating With An Airborne Laser?

Mon Jul 05, 2004 6:37 am

Hmm, it does sound rather rude. I suppose when you're doing that sort of "important" work it can get to you, in a way. Still, that shouldn't really be necessary. Flight Precision Ltd.'s work it apparently hassle-free traffic-wise -- that is, they slot their approaches in among the regular traffic. So, depending on what exactly Nav Canada is doing, keeping traffic well away shouldn't be that much of a problem. Hmm...

Cheers,
QantasA332

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