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Sloppy SLOP Procedure

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I flew a NATS track last night KJFK-EGLL and while enroute I read the AOM on Offset, and googled NATS SLOP to give it a try. Goodness! The 747X banked 30-deg to turn into a 2 nm offset.Now I only use HDG SEL to change track, along with using VS during step climbs.What do the real world systems do? Are they really designed to respond so abruptly?

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I think with carts in the isle,They use heading select and V/S.

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Dan:It's nice to have a chance to give something back to the author of our beloved SID/STARs :)- thanks!Yes, for SLOP, leave LNAV for HED SEL, build your SLOP offset, then gradually turn a few degrees towards; once established, turn onto correct heading and then go back into LNAV. Don't forget to delete the SLOP after leaving the NAT or at least well before Class B airspace.For step climbs get ready ahead of the step NOW, dial in the new altitude, select VS at 0000 and then slowly increase VS- I generally never climb faster than 400fpm (just a personal preference). Decrease the climb rate as gently as you increased it and the passengers in first will never even know you changed altitude ;). Re-establish VNAV and if you are in VNAV ALT, a press of the MCP altitude knob will establish VNAV PATH.Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png| XP Pro SP2 | 2 x APC UPS | Coolermaster Stacker 830 SE | Gigabyte P35 DS3R | e8500 @ 4gHz | Tuniq Tower 120 | EVGA 8800GT 512MB | Creative X-Fi Fatal1ty | 2 x 1 GB Corsair XMS2 | 2 x 320GB WD Caviar RAID 0 | Corsair HX620W PS | CH Products Yoke-Pedals-Throttle Quadrant | Aerosoft 747MCP-EFIS-EICAS |

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Or you could turn down the bank angle limiter

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The limiter only limits HDG modes, doesn't limit LNAV..I found 400 fpm works pretty good for the step climbs, I took the offset out before leaving the NATS track by simply hitting the 1LSB on LEGS twice (the top line is the next fix, in this case the one leaving the NATS) then EXEC while on HDG SEL, adjust manually then engage VNAV... no one noticed.I still wonder if this is how the real system works?While I'm still cleaning up the mess the cabin crew left me, I was also wondering if the holding patterns at EGLL's STARS (such as OCK) are usually not flown or usually are flown??

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Dan:Perhaps Steve or Alex will chime in. As far as the holds, EGLL gets busy enough where they are utilized- probably much more often than here in the US. Again, RW operators would be able to advise more definitively. Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png| XP Pro SP2 | 2 x APC UPS | Coolermaster Stacker 830 SE | Gigabyte P35 DS3R | e8500 @ 4gHz | Tuniq Tower 120 | EVGA 8800GT 512MB | Creative X-Fi Fatal1ty | 2 x 1 GB Corsair XMS2 | 2 x 320GB WD Caviar RAID 0 | Corsair HX620W PS | CH Products Yoke-Pedals-Throttle Quadrant | Aerosoft 747MCP-EFIS-EICAS |

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Dan,Holding for EGLL/EGKK is simply a matter of how busy the traffic is, I have never been instructed to hold at a fix inbound to EGLL in over 600hrs of online flying...but there will always be a first LOL!!That may be sooner than I think as I am currently on the way back to LHR from JFK (eta 2032z).As for the SLOP proceedure...there is a good example of RW operation in the Just Planes Oasis Hongkong DVD...on the EGKK-VHHH sector a SLOP is used buy the crew in Russian airspace...they go into HDG SEL mode prior to entering the offset then steer on to the new track before re-engaging LNAV.As for step climbs I to use V/S in the method Carl has descibed, it makes for a much more gentle & controlled climb to the new altitude.How did you find the SID/STAR file for EGLL??Kind RegardsSteve Bell

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During the day, you'd be pretty lucky to get into Heathrow without going round the hold at least once or twice. During busy periods, delays can quickly shoot up to 20 minutes in the hold. I'm sure there's something in the UK AIP that suggests operators load more holding fuel for Heathrow inbounds because of the likelihood of longer than normal delays.

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Steve: I've sent you an email at 'stephenbell@sky.com' with comments on the EGLL SIDSTARs... intended to be constructive.Thanks, Phil, I assumed the holds might be more common than in the US where the FAA has a pretty comprehensive flow control system in place. I've seen tracks at flightaware getting held, especially into that poorly designed NY area (just politics to blame) but the busiest places like KATL and KORD have 'em lined up in sequence 500 nm from the terminal airspace. Poor Heathrow and it's two runways and heavies coming at them from all over the globe.

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Hello,Maybe a stupid question but what is "SLOP" or "SLOP-procedures"?I know what NAT-tracks are, but SLOP is new for me:-roll

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SLOP= Strategic Lateral Offset Procedures.The idea that if aircraft on an airway offset their track by flying 1-2 miles right of the airway's center- they would still be well within the 10 mile airway corridor, but to the right of any aircraft passing in the opposite direction. Obviously if that aircraft is using SLOP as well, the safety margin is even greater.Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png| XP Pro SP2 | 2 x APC UPS | Coolermaster Stacker 830 SE | Gigabyte P35 DS3R | e8500 @ 4gHz | Tuniq Tower 120 | EVGA 8800GT 512MB | Creative X-Fi Fatal1ty | 2 x 1 GB Corsair XMS2 | 2 x 320GB WD Caviar RAID 0 | Corsair HX620W PS | CH Products Yoke-Pedals-Throttle Quadrant | Aerosoft 747MCP-EFIS-EICAS |

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Hi everyone,Just a question about SLOPs - when using Carl's example about RNP10, how does one guarantee that the aircraft is not 9nm from where it thinks it is, and if the pilot then enters a 2nm offset, the aircraft's actual position would then exceed the 10nm limit from the true airway centerline and be at 11nm from the centreline instead?In other word, isn't the FMC PP guaranteeing that the aircraft *is* within 10nm of the airway 95% of the time? If the FMC PP has a 9nm error (be it excessive, but still within the constraints of what the avionics is guaranteeing) then entering an offset could put the aircraft's real, physical, position outside of the airway limit?Does that make sense? I guess what I'm asking is, doesn't SLOPs partially remove the guaranteed buffer that RNP is designed for?Subin.

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Hi Subin,An aircraft has to be certified as being able to operate within the margins set for both RNP and RVSM. An aircraft declared as RNP/RVSM capable which cannot subsequently operate within these margins would put the operator in a heap of trouble.The biggest reported error, after investigation, of aircraft operating to these margins is GNE (gross navigational error) and this is nearly always attributed to the failure of the flight crew to take all necessary precautions. It is easy for us sim pilots to set up a route and expect the aircraft to follow it in, usually, not very busy skies. And using software like ServInfo, we get the impression on trans-oceanic flights, that we know where we are because the software shows us. In real life trans-oceanic flights, before the availability of GPS, pilots and ATC had to rely on calculated position reports for the correct maintenance of their separations. Now, even with GPS, pilots are required to regularly cross check their positions along a route by reference to times elapsed, navigation aids passed, etc.Next time you are on a long sector, try to regularly prove to yourself that you are where you believe you are. This is an excellent way to learn improved navigation techniques.Happy navigating,Richard

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It's easy to crosscheck the accuracy of your track, the information is provided by the FMC (go to pg 12-55 AOM) from the PROGRESS page select POS REF... you can see the differences between IRS and GPS, which is a good indicator of the quality of your estimated position. Depending on how many and where the satellites are in the sky, the GPS can usually put you within 0.1 nm (600 ft). The advantage to also having IRS is these systems are not suseptable to the occasional degradations in service that GPS has, and it is a truely redundant system.

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Hello,Thanks for clarifying things about SLOP.Now one more question : on the PROGRESS page 2/3 LSK2L, it says "XTK ERROR" ...Can these figures been changed, say 1NM, so you fly 1nm L or R from track ?Or is this just for information ?

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The crosstrack error cannot be set as you suggested, it is a measurement of where the aircraft is with respect to where the navigation computer would like to be. Offsets are set on the RTE page.

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Hi DanThanks for your reply. I thought it was something like that.But can you plaese point me in the right direction of to where exactly (what RTE page and/or in what format) the offset can be set?Thanks for the effort.

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William,For SLOP, you are only allowed to choose no offset, 1 mile right or 2 miles right offsets. So enter 'R1' or 'R2' at LSK 6R on the ACT RTE page 1 and press Exec. Dashes are initially displayed at LSK 6R when the offset option becomes available. On the ground, or on an inactive route page, or during a SID, STAR or approach procedure, an offset cannot be entered. The end point of an offset route is the first waypoint of an arrival or approach procedure, or a track change more than 90 degrees, or a route discontinuity.Hope this helps, Cheers, Richard

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Richard,Thanks or the update, it works.Never seen it before, always focused on LEGS-page!Again learnt something through this forum!

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Holy crap, you learn something new every day! Just when I thought I had the Queen down pat, along comes another trick. I just input 2R in the offset and it works like a champ. I didn't even have to use HDG, I just left LNAV enabled and it corrected, and followed the deviation perfectly. Was this proper if it followed the new path without issue?

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