Airports database

Where is the lat/long for a runway, as published in the airports database (airports.txt), physically located on the runway? Is it on the line across the runway just before the piano keys? If so, is it at the front of the thick line, at the back or midway? I have a research project trying to align the ARP lat/long, the runway lat/long and the reciprocal runway lat/long with a visual database. I am getting errors of 5-10m between database values and the visual system values.

The runway coordinates are the threshold of the runway, according to ARINC424.


For Manchester airport, the ARP is defined as the mid-point of 05L and 23R. The Navigraph aerodrome lat/long corresponds to the ICAO ARP but is not halfway between the 05L lat/long and the 23R lat/long, even though the lat/long for 05L and 23R are identical in the Navigraph database and the ICAO aerodrome chart. Is the threshold the start of the piano keys? I can’t find a diagram to clarify this point in ARINC 424.

The ARP has nothing todo with the rwy coordinates. This is a own point but completly independent from the runways.

It’s a luck, that the ARP at EGCC lies on the runway 05L/23R - if this is really the mid point, I don’t know but I wouldn’t expect it even when it looks so on the airport chart.

As I wrote before, the runway coordinates are the center threshold of the specific runway, the markers are inside it.


PS: I have checked the EGCC runway and ARP coordinates now against the UK AIP and the values are correct. So I’m not sure what you want report here, where do you see an issue here?

I am trying to integrate a visual database with the Navigraph airports database. I use the ARP as the origin of the visual database coordinate frame. The runway in the visual system includes a white outline, piano keys, touchdown markers and a centreline. I have a small error converting between lat/long and x/y in the visual database Cartesian frame, which I suspect is caused by an incorrect location of the runway coordinates in the visual database. But I cannot find anything in ARINC 424 that explains where the runway coordinates should be in my visual image of the runway. Does anyone have a diagram of a runway showing where the runway coordinates are located. I suspect it is as the start of the piano keys but it would be helpful to confirm this. Regards, Dave

Here, you see the lat/lon of the runway-threshold for 05L at EGCC:

… and here a general overview of 05L … the red-marker is the runway threshold position for 05L

Hope that helps,

Many thanks Richard, that clarifies my misunderstanding. I also found this FAA diagram. Regards, Dave.

This topic was automatically closed 2 days after the last reply. New replies are no longer allowed.