WILCO737 From Greenland, joined Jun 2004, 8761 posts, RR: 77 Reply 4, posted (8 years 6 months 4 days 22 hours ago) and read 1766 times:
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in our 737s (300/500) we just have GPS in I think 50% of the aircrafts... All others dont! There we use the good old IRS which will be updated all the time and we can achieve RNP5 with it, too! BUT with GPS we are now allowed to fly GPS approaches, but I havent flown one yet.
But GPS is for sure a great invetntion! It makes the navigation a lot more better! So, I am happy with having GPS on board...
Mandala499 From Indonesia, joined Aug 2001, 6409 posts, RR: 74 Reply 5, posted (8 years 6 months 4 days 21 hours ago) and read 1740 times:
As Ralgha said... it doesn't fly for you, and if you don't know how to use it properly, it can actually get you in a LOT of trouble... Then, also there would always be some that would "overuse" the GPS beyond it's specified limits (depending on receiver model and bravado of the complacent pilot).
As great as it is, many tend to forget that it is still prone to errors... A good friend of mine the other day flew a widebody twin over China and his GPS input to the ADIRU went haywire. The difference between the 2 GPSes were up to 50NM apart, and the averaging with the IRS+Navaid gave 3NM error... Something was wrong but they couldn't pin down the error until the ATC called him calling him 3NM off track... It's not nice knowing you're straying off course over a not exactly open door airspace and then have the ATC warning you for the error. Problem was solved by purging the GPS data and continued his flight to his homebase where the GPS miraculously came back to its normal self... Incident report has been filed and it's funny seeing "Space Invaders" being displayed on the ND...
GPS is great, but even like the INS, it carries its own problems... And sometimes, averaging out positions can still lead you to hazard. Despite all the aids and automation, keep your wits about!
Next time you look at your GPS, don't be surprised if you're >50m off... It's a Global Positioning System and not Getting Pilots Sleeping (yes a few have been caught)...
When losing situational awareness, pray Cumulus Granitus isn't nearby !
Glom From United Kingdom, joined Apr 2005, 2804 posts, RR: 10 Reply 6, posted (8 years 6 months 4 days 15 hours ago) and read 1642 times:
Quoting Soaringadi (Thread starter): But don't you think that its taking all the fun and challenge out of ifr flying....
If you want a challenge, then there's nothing better than trying to landmark navigate on a day of glorious VMC in far off lands. I did one recently but had a problem with identifying one of my turning point, a disused airfield, that was probably an inocuous grass strip in the middle of a sea of fields. I missed it but had a friendly RAF base nearby to help steer me towards my next waypoint.
Visual navigation is a great skill to have, but it is unforgiving.
Efohdee From United States of America, joined Oct 2004, 214 posts, RR: 0 Reply 7, posted (8 years 6 months 4 days 12 hours ago) and read 1594 times:
Quoting Glom (Reply 6): If you want a challenge, then there's nothing better than trying to landmark navigate on a day of glorious VMC in far off lands. I did one recently but had a problem with identifying one of my turning point, a disused airfield, that was probably an inocuous grass strip in the middle of a sea of fields. I missed it but had a friendly RAF base nearby to help steer me towards my next waypoint.
That's how that Cessna 150 almost flew over the whitehouse a few weeks ago.
GPS doesn't make "cloud flying" available to anyone. You still have to keep the aircraft under control and not get disoriented. Its just another tool available to navigate IFR or VFR.
Glom From United Kingdom, joined Apr 2005, 2804 posts, RR: 10 Reply 8, posted (8 years 6 months 4 days 12 hours ago) and read 1583 times:
Quoting Efohdee (Reply 7): That's how that Cessna 150 almost flew over the whitehouse a few weeks ago.
Fortunately, there is no White House in Camridgeshire. There is however an international airport with controllers that are by all accounts not very understanding about infringements. Fortunately, knowing the airspace was nearby, I knew enough about my position to turn directly away from their airspace so no infringement occured.
B744F From Germany, joined Jan 2006, 0 posts, RR: 0 Reply 9, posted (8 years 6 months 4 days 11 hours ago) and read 1572 times:
Quoting Mandala499 (Reply 5): Next time you look at your GPS, don't be surprised if you're >50m off... It's a Global Positioning System and not Getting Pilots Sleeping (yes a few have been caught)...
Sorry GPS is by far the most accurate system to date. If there was a problem over China, it could have been interference with all the US spy satellites or something.
And about the GPS making life easier, sure it does. Also VNAV LNAV eqiped aircraft make flying "easier." But then again, flying isn't any complicated thing, you just need to learn procedures and you would be good to go. As I've said in many other topics, it doesn't take a rocket scientists to fly a freakin airplane people.
Mandala499 From Indonesia, joined Aug 2001, 6409 posts, RR: 74 Reply 10, posted (8 years 6 months 4 days 7 hours ago) and read 1527 times:
It's accurate no doubt, and damn cost effective too... But it's not 100% accurate and 100% reliable... just that routine miniscule error and the occasional haywire that happens <0.01% of the time that can cause problems hence my post above... it makes the pay worth it getting through those kinds of things...
At least with GPSs I know I'll be accurate to 100m or so almost all the time. Though I'm still more impressed at the USAF "stargazer" kind of thing...12 hrs and your're only 50cm out! But damn sensitive equipment!
When losing situational awareness, pray Cumulus Granitus isn't nearby !
PlainSmart From , joined Dec 1969, posts, RR: Reply 11, posted (8 years 6 months 4 days 7 hours ago) and read 1510 times:
Future is GPS. Only problem are primary and training students letting their pilotage and other non GPS techniques go to waste. The basics are important for a solid background in aviation. It is important also though to keep with the times. WAAS is going to be huge.
Pilotpip From United States of America, joined Sep 2003, 3117 posts, RR: 11 Reply 12, posted (8 years 6 months 4 days 6 hours ago) and read 1495 times:
GPS is wonderful, if you know how to use it. When flying in IMC, it doesn't make it any easier. I would even argue that sitting there programming a GPS will make you more prone to spacial disorientation because you're moving your head around quite a bit figuring out the box. It also doesn't give you any sort of attitude information so you still have to use your standard instruments to fly the airplane.
One of the things my flight schools is preaching now is that too many students rely on the GPS and have very poor pilotage and dead reconing skills. In fact, a few have failed checkrides as a result. I've decided that my students will do their cross countries via the old fashion method on the outbound leg and if they do well, the GPS is a reward going home. This is something I do to this day. It's rewarding to know you can get where you need to go with a compass, chart, and a watch. Hell, Lindberg flew over an ocean this way, why can't I go get a $100 burger doing it too? The GPS system is great, but it can be shut off at the flip of a switch if the government feels that somebody is getting too close to something they shouldn't be near.
I've filed once with a GPS that I was not familiar with. I elected to go with airways and I think it was the smartest thing I did as I couldn't figure out how to use the thing. Learn your avionics. There's nothing good about driving a perfectly good airplane into the ground because you were trying to get the navaids off your moving map.
CosmicCruiser From United States of America, joined Feb 2005, 2254 posts, RR: 16 Reply 13, posted (8 years 6 months 4 days 6 hours ago) and read 1494 times:
This post seems to talking about both small plane and big plane GPS which maybe two diff. topics. In an INS/IRU plane the GPS aids in the accuracy of the INS/IRUs and that's a good thing. When you coast out across the ocean the IRUs are left to calculate their own position and "mixing" the avg. There will be an error that will develope but hopefully not much and if one generates a large error it's taken out "of the loop". The GPS will continue to provide accurate updates when you are already out of VOR/DME updates reception.
ShyFlyer From , joined Dec 1969, posts, RR: Reply 14, posted (8 years 6 months 4 days 4 hours ago) and read 1475 times:
Quote: Pilotpip, Reply 12
The GPS system is great, but it can be shut off at the flip of a switch.
It should be mentioned that ILS, MLS, NDBs, and VORs are subject to the same "Selective Availablity," however GPS seems to be the only one effected on a routine basis.
Quote: Albuquerque Center (NM) [ZAB]: June NOTAM #6 issued by Gps Notam OA [GPS]
GPS navigational unreliable and May be unavailable within a 330 nautical mile radius of the HOLLOMAN TACAN (HMN, 325144N/1060633W) at FL400, decreasing in area with decrease in altitude to 280 nautical mile radius at FL250, 210 nautical mile radius at 10000 ft. mean sea level and 200 nautical mile radius at 4000 ft. above ground level. the impact area also extends approximately 23O nautical miles at FL400 at the furthest point to the south, decreasing to APPROXI- MATELY 110 nautical miles at 4000 ft. above ground level. effective from June 10th, 2005 at 08:00 PM MDT (0506110200) - June 11th, 2005 at 04:00 AM MDT (0506111000)
What you mentioned about pilots not knowing how to "fly the box" prior to setting off on a flight is a good point. A good pilot should know how to use the equipment on board the aircraft before flying, or seek instruction. The buzz in the GA community is Technically Advanced Aircraft. The FAA is still working out how best to tackle the issue of properly training pilots in the use of all the new fangled gizmos.
Woodreau From United States of America, joined Sep 2001, 934 posts, RR: 7 Reply 16, posted (8 years 6 months 3 days 15 hours ago) and read 1377 times:
Quoting ShyFlyer (Reply 14): It should be mentioned that ILS, MLS, NDBs, and VORs are subject to the same "Selective Availablity," however GPS seems to be the only one effected on a routine basis.
There is no "selective availability" for ILS/VOR/NDB's. Yes the military can secure the ground based navaids by implementing SCATANA, but there has to be a really compelling reason to do so. (The last and only time SCATANA was implemented was 9/11/2001, but they didn't implement the ANA part of SCATANA only the AT part.)
That unreliable GPS zone near Holloman has pretty much been a permanent unreliable zone for several years now. Maybe they're testing some GPS jamming technology or something.
The reason why GPS can be unreliable at times are because the GPS satellite are old and need replacement, and when a satellite goes off line, it leaves holes in satellite coverage to meet aviation requirements. The GPS satellite constellation is in relatively good-to-fair shape, with a good 2/3 of the satelllites operating (launched in the mid-/late-1980's) well past their 15-year service life. New replacement satellites are going up every so often. In spite of this, GPS has a very good availability rate. Compare that to the Russian GLONASS constellation, which has less than half of it's satellites operational.
The implementation of GPS in transport aircraft and general aviation aircraft is different. In transport aircraft, GPS is an additional position sensor, complemented with DME/DME, VOR/DME, INS/IRS (if available). The FMS compares the positions generated by all the position sensors, and computes a separate "best" position solution based on all of the input it receives. There is some internal bias as to which sensor the FMS will favor - but that's something the pilot cannot change. All the pilot can do is turn off a specific sensor input. That computed position is the FMS derived position and that is plotted on the nav display. You can bring up a separage page which will display the raw position generated by each individual position sensor.
In general aviation aircraft, there is no box that compares the GPS position with other position inputs like the transport aircraft do. The pilot is responsible for comparing the GPS derived position, with VOR/VOR, and with outside visual references. (I haven't seen any GPS equipped GA aircraft that has DME installed.) But most times GA pilots don't do this. Even in the TAA aircraft, like a Garmin 1000 equipped aircraft, the moving map displays the GPS position only. You can't display a VOR/VOR crossradial position. With the way the GPS avionics are today, it's difficult to cross check your position with conventional VORs. With GPS, usually the #1 CDI is in GPS mode, so all the pilot has available is the #2 CDI to get a single VOR radial to cross check (unless the pilot also switches the #1 CDI to Nav mode and tunes another VOR to get a cross radial.) It's more difficult to cross check your position in a GPS equipped GA aircraft.
But yes the future is GPS (as far as the US is concerned)
[Edited 2005-06-10 15:34:48]
Good judgement comes from experience. Experience comes from surviving bad judgement.