HP 15CE Aviation Pac

[Geoff Quickfall]

Hi Max and others!

To further extend Max’s explanation:

1). On the 41CX and 71B I established a routine to check for alpha N, S, E and W. This would then assign a -ve or +ve value for the calculation in the routine. Yes, co-ordinates on the aircraft are entered as a +ve number with the alpha value attached to the front:

On Boeings and the DC10 INS N45 15.6 with seconds as a decimal.

2). There are defined (named) waypoints, those that are part of a programmed data base and undefined waypoints. Overseas operations differ from land based operations in that the waypoints that are not defined (undefined or unnamed) waypoints. These waypoints are not found in the data base and are entered by latitude and longitude. These occur on the North Pacific and North Atlantic and are based on the least time track (shortest fuel and time track),

Procedures for checking the undefined waypoints after the computer (FMC) is loaded require a total distance check (last page of the FMC), ETA for total route (winds are also inserted) and a distance and track check between each waypoint and compared to the printed flight plan created by a mainframe (for Air Canada we used Lufthansa flight planning).

Further, a reroute on the North Atlantic was not uncommon when entering Scottish Airspace north of the published tracks (Vancouver London/Frankfurt/Paris/Rome/ Europe) as our timing for entry was at the same time as the new published tracks for the next 24 hours were published and in use.

This is where the Distance.Track routine was used as it supplied the distance.track check independently of the FMC and since the reroute was not on a flight plan, there was no independent printed flight plan to compare too.

As stated, the distancd.track check MUST be done at the gate or in flight to confirm that the waypoint latitude and longitude were input correctly.

Thomas!

Yes, that is the reason!!! The formula does however, require that E and S be entered as negatives for the calculation only, it is an artifact of the forumula. See point 1 above. The onboard computer does the assigning itself based on the letter code N, S, E and W. The subroutines I created to check for polar and due North or south were for the standard oblate spheroid sine and cosine formula. If you check HP literature they provide some examples for the 25C and 29C(?) using the standard spheroid formula and advise that traversing the pole will provide and error.

Cheers