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Requesting Help With Navigation Systems  
User currently offlineSailorOrion From Germany, joined Feb 2001, 2058 posts, RR: 5
Posted (14 years 2 months 2 weeks 5 days 8 hours ago) and read 1967 times:

Hey all, I could use some information of some less-known navigation systems:

1) Is this system still in use?
2) If so, whats its precision, whats it used for, what onboard devices are used for it?

1) Whats the 'development status' of MLS? Will it be applied in the near future?

LORAN (any):

INS (or IRS):
1) Whats the average error per flight hour on state-of-the-art INS
2) is it certified to be used as 'sole means of navigation' for airliners?

ILS CAT-IIIc approach
1) How does the pilot stay on the runway centerline after touchdown and ILS signal loss if visibility is 0-0? Is there any additional transmitter, or does any ILS antenna have a BC signal which is usable for taxiing?

I'd really appreciate any additional operational information on those system, also what other not-well-known nav systems are used in civil aviation today (not ILS, VOR, NDB or GPS)


7 replies: All unread, jump to last
User currently offlinePikachu From Bhutan, joined Feb 2002, 89 posts, RR: 0
Reply 1, posted (14 years 2 months 2 weeks 5 days 6 hours ago) and read 1915 times:

OMEGA was decomissioned a few years ago.

(As far as I know)MLS once held great promise but has since fallen by the wayside.

IRS (or ADIRS in the Airbus world) On the 330 with three ADIRS and solely navigating with the ADIRS the Estimated Position Error is +8nm/h for the first 21 minutes and +2nm/h after that. I would suggest that unless there was a problem these limits would NEVER be approached.
Triple ADIRS are great for crossing oceans. Once you get within range of VOR's and NDB's again the ADIRS are all automatically updated to the exact postion and the airplane will correct it's course.

On a CAT III approach the airplane maintains the centerline following the autoland. If the transmitter drops off line there is a back-up that should provide continous transmission.

User currently offlinePPGMD From United States of America, joined Sep 2001, 2453 posts, RR: 0
Reply 2, posted (14 years 2 months 2 weeks 5 days 3 hours ago) and read 1900 times:

Well I am not sure what its accuracy in the air, Loran C has an accuracy of 1nm in most marine cases.

At worst, you screw up and die.
User currently offlineThirtyEcho From United States of America, joined Dec 2001, 1741 posts, RR: 1
Reply 3, posted (14 years 2 months 2 weeks 5 days 3 hours ago) and read 1906 times:

There are 2 possibilities for holding the centerline in 0-0 operations that can even be done manually. The first is to hold the localizer centered on roll-out and the second, should the localizer be lost, is to hold the exact runway heading. This method goes back as far as WWII.
The real difficulty comes after leaving the runway; hence the "Follow Me" vehicles you sometimes see.

User currently offlineZiggy From United States of America, joined Jun 2001, 178 posts, RR: 0
Reply 4, posted (14 years 2 months 2 weeks 3 days 8 hours ago) and read 1870 times:

MLS to my knowledge was a military endeveor, I think they still use it today, but unsure. It like ILS, but uses microwave.
Ziggy  Confused

User currently offlineSailorOrion From Germany, joined Feb 2001, 2058 posts, RR: 5
Reply 5, posted (14 years 2 months 2 weeks 2 days 7 hours ago) and read 1847 times:

Thanks guys, it helped me out  Big thumbs up


User currently offlineMD11Nut From , joined Dec 1969, posts, RR:
Reply 6, posted (14 years 2 months 2 weeks 2 days 6 hours ago) and read 1844 times:

Sorry for the late response. I've been away a while.
The Omega had a range of about 8000nm. Its accuracy was about 5000ft.

Loran-C had a range of about 1200nm with accuracy from 100 ft to 1200ft, depending on range. Loran-C is still being used by ships, not sure if there's any airborne use anymore (not on airliners anyways).

The INS can be used as sole means for RNP-10 airspace (for up to 12.5 hours).

MLS for commercial aviation is no more. The FAA abandoned it long ago. The future implementation is LAAS.

The Localizer beam is used on the ground (during rollout and takeoff) to maintain centerline.

Hope this helps. Best Regards,

User currently offlineCaptrig From United States of America, joined Mar 2002, 4 posts, RR: 0
Reply 7, posted (14 years 2 months 1 week 4 days 7 hours ago) and read 1819 times:


We used OMEGA nav on our Boeing 727-2M7's out of Guam. The navigation is ground based, low frequency. The unit will pick up a minumum of 3 stations, and triangulate the aircraft's position. Accuracy was fair. It frequently would go into DEAD RECONING the instant the airplane poked it's nose into a cloud.

We had two sets on board. The challenge when leaving Seoul (Korea) for Guam was to get an update when passing over known navigational facilities. We would usually do this at Ikeshima, on the north west coast of Honshu, and then again after passing the last land position at a DME fix off of the final VOR station. Sometime along the route, it was normal for one of the two units to begin telling us bad information. The question was, "which one?" We could get an accurate fix off the Iwo Jima TACAN with bearings off of the Anderson NDB on Guam and the IWO NDB.

These were nice units when they worked... by Tracor our of Mojave, CA. A $35,000 card would convert the unti to SATNAV... but the company figured they paid us to do the navigating, and they were right. It's an OK system.

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