RayChuang From United States of America, joined Jun 2000, 7860 posts, RR: 5 Posted (10 years 1 month 3 weeks 4 days 17 hours ago) and read 1585 times:
According to some theories, the unfortunate KE 007 shootdown was caused by the fact the pilot of the plane did not program the inertial navigation system (INS) properly, which resulted in the plane going off-course and into Soviet territory on its flight from ANC to SEL in 1983.
With today's GPS (and after 2008, Galileo) satellite navigation systems (which has accuracy around 10 meters), do airliners still need to program the INS system while the plane is on the ground? Or is INS replaced by systems that work by receiving satellite navigation signals?
B747skipper From , joined Dec 1969, posts, RR: Reply 3, posted (10 years 1 month 3 weeks 4 days 11 hours ago) and read 1461 times:
The Classic 747s sure still have INS...
The airplanes I presently fly are equipped with 3 INS (which are operated in "triple mix") - and we have 2 GPS to update #1 and #2 INS... By triple mixing it also updates the #3 INS... We also have DME update capability.
All that gives us maximum accuracy for RNP-5 operations (MNPS)...
JBirdAV8r From United States of America, joined Jun 2001, 4471 posts, RR: 21 Reply 4, posted (10 years 1 month 3 weeks 4 days 11 hours ago) and read 1447 times:
You can think of it this way.
The main advantage of the Inertial Navigation System, or INS, is simply that it's internal...fully contained in the aircraft. One disadvantage is that on average, it loses accuracy at the rate of about one nautical mile per hour.
The main advantage of GPS is of course its accuracy. GPS signals for civilian use, however, are very weak....extremely weak, in fact....and may provide inadequate reception and with loss of RAIM can be error-prone in some areas.
So GPS in a transport-category airplane that's equipped with an INS type system periodically updates the INS, thereby producing the "best of both worlds" so to speak.
AJ From Australia, joined Nov 1999, 2380 posts, RR: 26 Reply 5, posted (10 years 1 month 3 weeks 4 days 9 hours ago) and read 1429 times:
Qantas 747-400s use three IRS (Inertial Reference Systems, not the tax man) updated with VOR/DME and two onboard GPS.
The 767s use three IRS updated with VOR/DME, with several aircraft equipped with GPS.
The 747-300s use three INS, however they are now being updated with IRS and GPS as part of a refit.
B747skipper From , joined Dec 1969, posts, RR: Reply 7, posted (10 years 1 month 3 weeks 4 days 2 hours ago) and read 1340 times:
Dear L-188 -
With 2 GPS - you can continue with one GPS remaining if second fails, the one unit will provide sufficient update, to the INS in "T-Mix"... Our current configuration still gives full flexibility, i.e. in cas of one INS on MEL... It was the least inexpensive upgrade, using these LTN-92 type INS systems. Remember, DME update requires DME stations... not too many right in the middle of the oceans...
Happy contrails -
Don From Japan, joined Jun 2003, 268 posts, RR: 0 Reply 8, posted (10 years 1 month 3 weeks 3 days 4 hours ago) and read 1226 times:
If my memory serves me correctly, KAL 007 INSs were programmed correctly but they left the Navigation mode select switch in HDG position instead of INS position. So basically INS were not given the task of navigating. It was not an INS error but a pilot error.
I am not familiar with the latest generation aircrafts but I suspect that even on today's most sophiticated aircrafts same mistake can happen , But track deviation alert and warnings are better, I am sure.
B747skipper From , joined Dec 1969, posts, RR: Reply 11, posted (10 years 1 month 3 weeks 3 days 2 hours ago) and read 1219 times:
Dear L-188 -
Very well aware of "dead spots" in Polar areas - but if we lost the update capability (from GPS) for 1 hour or 2... the INS in T-Mix keep sufficient accuracy to even be called capable of MNPS (RNP-5)... no problems in case that happens...