coordiantes for Shoreham?

[liam548]

Im awaiting the southern chart but my confuser lists Shoreham as N5050.03 E00017.57

but Wikipedia lists it as 50°50′8″N 0°17′50″W


??

[Genghis the Engineer]

Try using an aviation publication, rather than an exam guide or unverified website!

UK AIP? Pooleys? AFE VFR guide?

Oh yes, and the two sets of co-ordinates you've posted look about the same to me. It's just that one is decimal and the other is in degrees, minutes and seconds.

G

[Put1992]

the confuser got that (and a few other) co-ordinates incorrect from what i remeber!

[Shunter]

Why not use Google Earth? Click your little mouse right in the middle of the runway and see what it says....

[liam548]

the confuser got that (and a few other) co-ordinates incorrect from what i remeber!

thats what ive found too. It should be N5050.03 W00017.57 not E00017.57

[India Four Two]

It should be N5050.03 W00017.57 not E00017.57The perils of living astride the Greenwich Meridian.

A harmless mistake when entered on a bulletin board, but nearly catastrophic when a E instead of a W was entered into the FMC of a 737 at Heathrow. This 34 nm error caused a complete loss of primary attitude and navigational information. A major disaster was narrowly averted by ATC assisting the crew to return to Heathrow. The report makes very interesting reading
http://www.aaib.gov.uk/sites/aaib/cms_resources/Boeing%20737-500,%20SP-LKA%2006-08.pdf

Edited to add that the thing that amazes me most about this incident is the crew noticed the failure immediately after takeoff, but continued their climb into the 1500' cloudbase, instead of remaining VMC and declaring an emergency.

[liam548]

The perils of living astride the Greenwich Meridian.

A harmless mistake when entered on a bulletin board, but nearly catastrophic when a E instead of a W was entered into the FMC of a 737 at Heathrow. This 34 nm error caused a complete loss of primary attitude and navigational information. A major disaster was narrowly averted by ATC assisting the crew to return to Heathrow. The report makes very interesting reading
http://www.aaib.gov.uk/sites/aaib/cms_resources/Boeing%20737-500,%20SP-LKA%2006-08.pdf

Edited to add that the thing that amazes me most about this incident is the crew noticed the failure immediately after takeoff, but continued their climb into the 1500' cloudbase, instead of remaining VMC and declaring an emergency.

Very interesting reading. Confuser getting it wrong just confused me for a short while and got me questioning if I actually understood how to read the coordinates!!

[IO540]

Funny that .... I would regard entering waypoints by coordinates as the #1 disaster area in GPS usage, and something one never does.

I've done it on extremely rare occassions; last time I think was the location for some little Spanish airport (LEAX) c. 2003 but by 2004 it was in the Jepp database anyway.

Do airline pilots really do this???

[S-Works]

Do airline pilots really do this???

I seem to recall that some FMS units are positioned using known Lat/Long co-ordinates in the inertial nav. You enter the stand position during giro alignment. If that is entered incorrectly then you get the error described earlier.

Maybe one of the heavy tin drivers can confirm.

[Mariner9]

Funny that .... I would regard entering waypoints by coordinates as the #1 disaster area in GPS usage, and something one never does.

Personal choice IO. I've got around 70 waypoints, farmstrips etc manually entered by lat/long into my Skymap III without any disasters ensuing.

GIGO of course applies, but manual coords can be safely entered with appropriate care.

[JW411]

On the DC-10 we had three INS (Inertial Platforms) which were capable of cross-talking. The present position was entered most carefully by the operating pilot and monitored by the other pilot. The alignment process took 17 minutes and during that time the aircraft could not be moved (or even have the tug attached) otherwise the platforms would topple and you had to start all over again.

It was not possible to enter the latitude in error by more than 4 nautical miles for the platforms knew the exact precession rate for a given latitude and would not erect.

Longitude was the big problem. If the present position was entered as East instead of West, the platform had no means of knowing whether that was right or wrong (the distance between the Meridian and 10W, for example, is exactly the same distance between the Meridian and 10E for any given latitude). That is what happened to the Korean 747 that got shot down by the Russians if my memory serves me right.

All waypoints (1-9) were indeed entered by hand and carefully checked by the other pilot and also checked against the Plog and against special charts that we carried for that purpose.

I later flew an ex-Air New Zealand DC-10 which had the facility to automatically load waypoints from a prepared tape which was fed into the nav-computers (Collins AINS 70 system). That was fine as long as the waypoints had been loaded correctly on to the tapes by the planning department in the first place.

Part of the cause of the ANZ DC-10 disaster, when it hit Mt Erebus in Antarctica, was because a chap in the planning department had decided they could save 17 nms by removing one of the waypoints from the tape. This was true but the new track took them straight through the mountain so the flight was cut short by rather more than 17 nms.

[Fright Level]

Do airline pilots really do this???

Pre GPS, the aircraft position/gate was entered into the IRS. The system can actually calculate it's latitude pretty quickly due to the precession rate but it has no idea of longitude until you tell it. Many airports have the stand lat/long on a big board in front of you so you can check. The Aerad charts have all stand co-ordinates listed so you can enter/check your position.

When you put the departure runway into the Boeing/Honeywell FMC it knew the threshold co-ordinates from it's database (which you then offset by x hundred meters if you planned an intersection departure). When you advanced the thrust levers to take off, the position was updated accurately as the FMC assumed you were taking off from the actual runway position it "knew".

Entering long string lat/longs is quite common for new waypoints, positions you need to reach that are not in the database (eg composite tracks over the Atlantic). Fortunately most are just whole numbers but there are some positions that are similar to "N2530.0 W08600.0".

With GPS aircraft, they still run IRS systems but the GPS provides another source of position information along with the INS position, DME/DME, VOR/DME and VOR/VOR positions (with the obvious accuracy improvement). The aircraft position on the gate is always checked prior to departure as part of the FMC set up.

In the example below the "SET IRS" position box would be blank/dashed until you entered the position (simply just a copy/paste from the stored database gate position above it).

http://www.b737.org.uk/images/fmc_pos_init.gif

PS Thanks to The Boeing 737 Technical Site (http://www.b737.org.uk/) for loan of the image!

[BRL]

Co-ordinates N 50 50.13 W 000 17.83 (WGS 84), centre of runway 02 / 20.

From Shoreham Info (http://www.shorehamairport.co.uk/pilot-airfield.asp)

[India Four Two]

Do airline pilots really do this???

In this case, yes. To summarize from the report, they did a normal INS "fast align" (30 seconds) at the gate, but the FO entered the erroneous E and then did not notice the FMC error message warning that the position entered was not close to the gate position in the FMC data base.

At the holding point they noticed the error, put the INS in Align mode, entered the correct Longitude and started the "fast align" again. At this point they were cleared for take off and started to taxi before the alignment was finished, so they departed with no attitude or nav data on the displays. They also left the INS in Align rather than Nav mode.

[IO540]

Of course coordinates "can" be entered manually.

The issue is that there is no "second level protection".

In any process where there is risk involved, one tries to arrange the process so that the following step will expose an error in the previous step(s).

In this case, a kind-of suitable check might be to display the route (on a nice big GPS screen, or an MFD) and check that it looks right. Yet the kind of pilots who will be entering manual coordinates are those not likely to have a "decent" GPS.

In the airline world, the 2nd pilot is supposed to check the coordinates, which is why (in theory) the airways charts all have the lat/long printed next to every waypoint. How many people actually do this?? Every digit I mean.

The next Q is whether you would rely on such a waypoint for terrain clearance when flying in IMC, especially in a terminal area ;)

[dont overfil]

There is a lot not in the Jeppeson database used in GA aircraft so co ordinates regularly need to be entered. I find radial and distance from a VOR easier to enter than a lat and long but of course that option may not be available and is not as accurate (when you get it right).
DO.

[Paul Morgan]

I too am revising for a Nav Exam that I was going to ttake later this afternoon. Thought I was going mad when I could not confirm the Long and Lat for Shoreman in the Confuser exercise! Typed "Long and lat for Shoreman" and up popped your thread. Very reassured I'm not loosing it!

[Blues&twos]

Shoreman???

[liam548]

I too am revising for a Nav Exam that I was going to ttake later this afternoon. Thought I was going mad when I could not confirm the Long and Lat for Shoreman in the Confuser exercise! Typed "Long and lat for Shoreman" and up popped your thread. Very reassured I'm not loosing it!


seems we all have the same issues. What you dont want to be doing while learning new subjects is coming across errors in the training material!!

[LH2]

The report makes very interesting reading
http://www.aaib.gov.uk/sites/aaib/cm...KA%2006-08.pdf

Indeed. :eek: Essentially the crew were unable to navigate the aircraft on standby instruments (i.e., C172 style: HSI, altimeter, ASI). I would have never thought that could happen in a European B737 operation.

Judging the ATC actions from what is described in the report, and from personal experience elsewhere, I would say LHR was a great place to have this kind of problem--certainly I wouldn't want that to happen to anybody in, say, BCN.

the thing that amazes me most about this incident is the crew noticed the failure immediately after takeoff, but continued their climb into the 1500' cloudbase, instead of remaining VMC and declaring an emergency.

They did declare an emergency all right , and they attempted (not very skillfully though) to do what they are supposed to do, which is fly the departure. Commercial flying has very little in common with recreational flying (as illustrated by their inability to steer the ship using the good old steam gauges).

Correction: They did not, actually, nor one was initiated by ATC. I misread part of the report.

Lastly, I have to disagree with your following comment:

A major disaster was narrowly averted

No it wasn't. A B737 getting lost is not anyone's idea of a good day out I wouldn't think, but your comment is sensationalist. According to the AAIB report, at no point was control of the aircraft compromised, merely its navigation.

Interesting report nonetheless. :ok: