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Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 4:35 am
by vikkyvik
This has been puzzling me for years now. In various shots of Kai Tak, the approach lights are sometimes red:


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Photo © Lawrence Chiu
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Photo © Alan Tsui



...and sometimes white:


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Photo © Samuel Lo
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Photo © Olaf Juergensmeier



Did they actually change the color at some point? Were they changed to let an approaching aircraft know whether to continue the approach or not? Or a departing aircraft whether to depart / enter the runway or something? Why haven't I asked this question in the ~8 years I've been wondering about it?

Thanks for any insight.

RE: Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 4:42 am
by Starlionblue
Discounting the Emirates one because it is taken from the runway outward, while the other three are from outwards towards the runway.

In the BA and QF pics they are the same color (white + white/green for the threshold). In the CX pic the threshold lights are white/green, just like in the BA and QF pics. However as you say in the CX pic the two rows behind the threshold lights are red, while they are white in the BA and QF pics.

The obvious difference is that the CX plane is lined up to take off, while the QF and BA planes are approaching.

Interesting...

[Edited 2013-03-26 21:44:29]

RE: Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 5:15 am
by vikkyvik
Quoting Starlionblue (Reply 1):
Discounting the Emirates one because it is taken from the runway outward, while the other three are from outwards towards the runway.

Not sure I understand - the runway threshold and approach lights are visible in that image above the two aircraft. The first roll bar of the approach lights is visible on either side of the light pole.

Quoting Starlionblue (Reply 1):

The obvious difference is that the CX plane is lined up to take off, while the QF and BA planes are approaching.

Indeed. That's why I wondered whether they could be switched to warn approaching aircraft not to land (maybe because the offset approach makes checking runway clearance more difficult?).

RE: Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 6:14 am
by Starlionblue
Quoting vikkyvik (Reply 2):
(maybe because the offset approach makes checking runway clearance more difficult?).

Maybe, but you could certainly see the runway on approach, perhaps even better since given the angle you could more easily see how far along the runway other aircraft were. And wouldn't the tower know?

Quoting vikkyvik (Reply 2):
Quoting Starlionblue (Reply 1):
Discounting the Emirates one because it is taken from the runway outward, while the other three are from outwards towards the runway.

Not sure I understand - the runway threshold and approach lights are visible in that image above the two aircraft. The first roll bar of the approach lights is visible on either side of the light pole.

Heh. I see it now. I thought that picture showed the southeastern end of the runway. Now that I think about it, it shows the northwestern end as you say.

RE: Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 7:55 am
by CCA
It's the angle of the approach if you're too low (dangerously low) they're RED so everything from ground level is red a normal approach is white so the elevated pics are white as they should be. The PAPI would be all red before the approach lights were seen as red.

[Edited 2013-03-27 01:04:24]

RE: Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 8:40 am
by Starlionblue
Quoting CCA (Reply 4):

It's the angle of the approach if you're too low (dangerously low) they're RED so everything from ground level is red a normal approach is white so the elevated pics are white as they should be. The PAPI would be all red before the approach lights were seen as red.

If you were that low at Kai Tak you were probably in some old Chinese granny's living room. 

RE: Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 12:19 pm
by FlyASAGuy2005
That would be the PAPI lights guys.

RE: Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 12:42 pm
by Starlionblue
Quoting FlyASAGuy2005 (Reply 6):
That would be the PAPI lights guys.

The lights mentioned are on the runway surface before the threshold. The PAPI lights are visible on both sides of the runway.

RE: Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 2:45 pm
by Pihero
An interesdting set of pictures which bring back fond memories of Kai Tak:
The airport had some non-standard approach lights because of the RWY 13 geometry.
- Directional white lights were used for low visibility conditions.
- On the same pylons, one would have omni-directional red lights to remind aircrews of the displaced touch-down zone for good visibility conditions. The first picture shows very accurately the twin-bulb set-up of the approach lights.
- The two red bars - in front and behind of the departing airpalne on the first picture - were also used by the Tower control as **stop** bars, switched to white with one's takeoff clearance.

There is a puzzling feature in this picture : there used to be a 4-light PAPI but apparenhtly we only see 3 lights . I don't remember the PAPI being downgraded before the closure of the airport.

RE: Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 4:53 pm
by intsim
Quoting Pihero (Reply 8):
There is a puzzling feature in this picture : there used to be a 4-light PAPI but apparenhtly we only see 3 lights . I don't remember the PAPI being downgraded before the closure of the airport.

It looks like the fourth light is behind the CX 744 vertical stabilizer. There is red light to the left of the tail that doesn't look like it could come from the three visible lights. I think the fourth light on the left set is just cut out of the picture.

RE: Kai Tak Approach Lights

Posted: Wed Mar 27, 2013 6:34 pm
by Pihero
Quoting intsim (Reply 9):
It looks like the fourth light is behind the CX 744 vertical stabilizer.

You are right : one can see the glare of that light.
Many thanks for clearing it up !

Regards.