B757 Undifferentiated or Other Model
Human-Machine Interface; Training / Qualification
ATC Issue All Types; Aircraft Equipment Problem Less Severe
General None Reported / Taken
Aircraft; Procedure
The new NATS procedures went into effect. After reviewing the NATS briefing download that my Captain recently received; it became apparent to us that there is a major flaw in the procedures that could have catastrophic consequences due to gross error navigation:1.) The new procedures require the use of Latitude separations of 25NM by using 30' coordinates in an effort to reduce the separation between tracks. The 757/767 Nav Database in it's current software version only shows 5 characters in the Legs page and will not identify a 30' offset. (Example: N48W050 could have the coordinates of N48.00 W050.00 or N48.30 W050.00). It will create two or more way points with the SAME NAME. The only way to see this is by expanding the coordinates. This in effect causes an ambiguity that once the procedures are implemented could cause a gross navigational error. 2.) The RNP is now required to be set at 4.00 manually. Currently the software automatically sets it to 10.00 when on the tracks. 3.) SLOP (Strategic Lateral Offset Procedure) is not always implemented on the tracks.4.) Crews are not formerly trained and yet they are now required to implement these procedures.Similar to when LAHSO was first implemented Unions joined together to rescind the poorly introduced procedures. I/we recommend rescinding the use of these procedures as they are currently written.- Update software to allow for LAT/LONG in the legs page to show accuracy of 1' (1 minute lat/long)- Update software to automatically set RNP to 4.00 on all tracks.- Require SLOP as mandatory on all tracks and enforce.(Currently it may be mandatory however its not always practiced)- Require formal training before use of these procedures.
The reporter has two main concerns. The first was the B757/767 Pegasus FMS display limitation of only five characters in the route pages which by design truncates the full oceanic waypoint description. For example N50300 W04000 is displayed at 5040N the same as N50000 W04000; so the possibility exists that with 30 mile oceanic track separation and a 30 minute waypoint error; two aircraft could be on the same track. The reporter felt aircraft with this limitation should not fly the RLATSM. Reporter's second concern is pilots not offsetting oceanic tracks 1 -2 NM as per the Strategic Lateral Offset Procedure (SLOP). Should a track error such as expressed here occur; a SLOP would help mitigate the potential consequences.
A B757/B767 pilot reported the Pegasus FMS display five character limit prevents full 30 minute latitude display. After entry; such as N50300 W04000; the display is 5040N; the same as N50000 W04000. This may lead to a 30 minute error and the possibility of an airborne conflict. Reporter suggests the use of Strategic Lateral Offset Procedure (SLOP) should be emphasized.