10 replies to this topic

[slick]

Hello people,

Has anyone tried landing at Phuket airport ILS runway 27??
Can someone please confirm that it is inaccurate and the plane always land 1-2 degress off to the right.

This must be a Microsoft bug...........

[IBtheSarge]

slick, on May 31 2005, 09:19 PM, said:

Hello people,

Has anyone tried landing at Phuket airport ILS runway 27??
Can someone please confirm that it is inaccurate and the plane always land 1-2 degress off to the right.

This must be a Microsoft bug...........

Are you experiencing this because you're lined up on heading 270?  If so, take a closer look at the Phuket runway data:

Runway DESIGNATORS = 09/27
Magnetic Variation for Phuket = -0.9

Runway True Headings = 84.9/264.9
Runway Magnetic Headings = 85.5/265.5

Runway designations are the first two digits of the three-digit magnetic heading, to the nearest whole number.  There are no runway designators 85.5 or 265.5 (FS9 or real-world) ... they are rounded up to 09 and 27 (respectively).  ATC willl clear you to land "Rwy 09" or "Rwy 27"; however, as an aviator, you are supposed to check your charts (map display mode, point-click on the runway and read the data for the runway you intend to land on) when flight planning to learn that Rwy 27 was not poured on a physical alignment of 090/270.  A lot of factors go into pouring concrete for a runway, particularly soil type, terrain features, environmental concerns, water table, etc.  Phuket was poured on magnetic headings 85.5/265.5, which ATC lists as 09/27.  Also, since the mag var changes year-to-year, the original runway could very well have been poured 090/270, but the variance over the years has altered the heading to 85.5/265.5.

Just another reason to align via instruments, but once you have the runway visual, fly the approach manually to correct for heading.

[axvx8xoxr]

sarge, on Jun 1 2005, 12:41 AM, said:

slick, on May 31 2005, 09:19 PM, said:

Hello people,

Has anyone tried landing at Phuket airport ILS runway 27??
Can someone please confirm that it is inaccurate and the plane always land 1-2 degress off to the right.

This must be a Microsoft bug...........

Are you experiencing this because you're lined up on heading 270?  If so, take a closer look at the Phuket runway data:

Runway DESIGNATORS = 09/27
Magnetic Variation for Phuket = -0.9

Runway True Headings = 84.9/264.9
Runway Magnetic Headings = 85.5/265.5

Runway designations are the first two digits of the three-digit magnetic heading, to the nearest whole number.  There are no runway designators 85.5 or 265.5 (FS9 or real-world) ... they are rounded up to 09 and 27 (respectively).  ATC willl clear you to land "Rwy 09" or "Rwy 27"; however, as an aviator, you are supposed to check your charts (map display mode, point-click on the runway and read the data for the runway you intend to land on) when flight planning to learn that Rwy 27 was not poured on a physical alignment of 090/270.  A lot of factors go into pouring concrete for a runway, particularly soil type, terrain features, environmental concerns, water table, etc.  Phuket was poured on magnetic headings 85.5/265.5, which ATC lists as 09/27.  Also, since the mag var changes year-to-year, the original runway could very well have been poured 090/270, but the variance over the years has altered the heading to 85.5/265.5.

Just another reason to align via instruments, but once you have the runway visual, fly the approach manually to correct for heading.

    

Very well said ... also notice on the instrument approach plates (if you have them/know how to read them) many runways such as "27" have inbound headings of 272, 271, 273, etc..a few degrees can make a big difference when shooting an instrument approach.

[slick]

I've checked the flight chart and have entered course heading 265 for runway 27 just like what the flight chart data indicates but it still takes me off course to the right. Maybe I'll try visual.

[kewlceo]

slick, on May 31 2005, 11:24 PM, said:

I've checked the flight chart and have entered course heading 265 for runway 27 just like what the flight chart data indicates but it still takes me off course to the right. Maybe I'll try visual.

Is the scenery/AFCAD file default? I'm not that familiar with Phuket other than that I enjoy saying the name.

[dolbinau]

Is it not normal to be slightly off-centered with ILS landings?

[Ruahrc]

I think this is a little OT but in the real world sometimes GA pilots shoot ILS approaches 1/2 a dot left or right and only at the very end line it up in the middle.  The reason for this is that if your OBS needle is recieving no station at all (i.e. it has failed or is not tuned correctly) the needles go to the center.  As a safety check against this- they fly 1/2 a dot off each needle so that they know they are still recieving the station.  Yes there are to/from/gs tags but in case those fail too...  They also do this for VOR navigation sometimes too.

That way you are not surprised in the middle of "your best ILS approach ever" in poor weather (cause the needles are rock steady and dead on in the middle) suddenly you are staring at the ground or some trees.

Ruahrc

[IBtheSarge]

dolbinau, on Jun 1 2005, 02:37 AM, said:

Is it not normal to be slightly off-centered with ILS landings?

If a given runway 27 is indeed laid out, with consideration for mag var, on a true/magnetic heading of 270, you should be dead center of the runway centerline on an ILS approach.  The glideslope and localizer are calibrated to broadcast the beams down the centerline, even though the units themselves are physically off-set from the runway.  However, in some cases, "drift" will occur.  The units are "supposedly" recalibrated anytime the mag var changes.  Sometimes that doesn't occur "on time."  That's why ATC requests that you report the runway in sight, even on an instrument approach, so you as the pilot can safely operate your aircraft in accordance with the FAR/AIM and land on the runway.      The only time I've ever flown an instrument approach and was NOT told to report the runway in sight was on a PAR, and at 10 ft above the runway, RAPCON told me I should have visual at that point.  (On a PAR you are not supposed to be watching anything but your instruments until just prior to touchdown.)

[kewlceo]

dolbinau, on May 31 2005, 11:37 PM, said:

Is it not normal to be slightly off-centered with ILS landings?

Good question, Cam. I guess I don't know the answer since I fly the approach manually 99% of the time.

(Does anyone have a good "shrugging shoulders" type smiley?)

[sweetfracture3]

At KAGC, my home airport, the localizer actually takes you a bit left of the runway. No clue as to why it does this, but it most definalty does. I'm not sure if this is simulate in FS - probably not, but it does happen in the real world.

[IBtheSarge]

sweetfracture3, on Jun 1 2005, 02:58 PM, said:

At KAGC, my home airport, the localizer actually takes you a bit left of the runway. No clue as to why it does this, but it most definalty does. I'm not sure if this is simulate in FS - probably not, but it does happen in the real world.

Oh, yeah; happens a LOT in real-world.

Budget cut-backs, and realignment of the localizer/glideslope beams due to annual changes in the mag var are put on hold (not cheap to do).  Since ATC requires visual acquisition of the runway prior to landing and requires the pilot to state AFFIRMATIVELY that he has the airport in sight, it's not a "safety of flight" issue.  That's how airport management bean-counters justify not spending money for the realignment.