Northwest DC-9 FMS question

[Airbus_A320]

Most comments here seem to be insinuating that either GPS, or VOR to VOR are the only navigation options... they aren't!

You're forgetting probably the most important navigation tool... INS/IRS.

Qantas' 767's don't have GPS, but still fly thousands of miles away from the nearest VOR. Thats what Inertial systems are for.

Is that what RNAV is based on, the INS system? Also does RNAV gives the same basic effect as having a GPS, not having to use VOR's or ground based aids, except the difference is that the GPS uses satellites and the RNAV itself is contained in the plane, but has to be aligned every once in a while from a known position when the plane isn't moving?

Correct me if I'm wrong, I want to know how it actually is.

[MCM]

INS/IRS systems are indeed "aligned" from a known position when stationary. This happens preflight, and its important not to move the aircraft while its happening.

This is a fairly complex area, but I'll try to keep it brief and simple.

RNAV is just the term for navigation without the use of ground based aids. This included updates to the aircraft navigation system through the use of GPS.

These systems do "wander" over time, and the accuracy degrades after longer periods in the air. There are different standards of navigation requirements depending on the airspace, and airroute structure etc.

Much airspace (say, oceanic) is RNP10. This (to keep it simple) means that the aircraft must be capable of keeping within 10nm of track 95% of the time.

With a ground alignment only, the 744 is permitted to fly for 12 hours in this airspace.

Inflight, the system can be updated. This is done through the use of either GPS, or through ground aid updates. If the aircraft flies within the range of 2 DME stations, the nav system updates itself and then the aircraft can fly for another 11.7hrs without another update.

GPS updating these days is very common, and with GPS upadating on, the 744 can fly to RNP10 for an unlimited period.

RNP4 requires GPS.

P-RNAV is the use of these procedures for terminal area operations. A requirement of nav to 1nm is required.

Just out of interest, the 744 regulally sits at about 0.3nm with GPS on.

There are also some specific RNAV (RNP) approaches, however we don't do them on the 744. The 737-800 can do them, and its pretty impressive to see. The future of air navigation!

[Airbus_A320]

Alright, thanks for summing it up! I was always wondering what the relationship between the systems was.

I looked in the AIM and it seems like most of it is explained in depth there too, so for an indepth understanding i'll read through that section when I get a chance. For now I'll just focus on passing the PPL check though

[Crism]

There is no FMS on the NW DC-9's. The autopilot can't even fly a course. Its all hand done. Now thats what I call flying.

Basically you're dad's the man haha.

And Chasen, Freedom Air's Crash 8's that flew around outta JFGay flew using VORs. No GPS on that piece of crap. Planes sucked anyways. I'm not surprised.

[mikecweb]

/w baby.

[LRJet Guy]

Freedom Dash 8's....

I'll share a little something. We have serial #9 (906HA). Freedom flew one older than that.....

Our -100's have a KNS-660, which is a VOR based RNAV system. It's not a bad unit, but can be unreliable at times. Our manuals require the FO to back up the course via VORs when navigating with the KNS. The system is dependent on VOR reception, so there are places where it doesn't work, and many times you have no info from it on approach. It also takes a while for it to figure out where it is after you initialize it.

Our -300s have a UNS-1B, and we have one with a -1C as well. Very nice system that is GPS based, cross referenced with VOR data. It monitors fuel flows, etc, and will do pretty much anything you ask it to do including holds and approaches. We're not certified on GPS approaches, but we have the capability. It also has a VNAV feature although we rarely use it.

I'm not sure what the -400s have in them. I've never seen one, and never will since I just resigned! I fly my last trip at the end of the month.

[Airbus_A320]

And Chasen, Freedom Air's Crash 8's that flew around outta JFGay flew using VORs. No GPS on that piece of crap. Planes sucked anyways. I'm not surprised.

Are those things still even around? I know they started flying late to begin with, then I saw them over last winter, then I started seeing ERJ's again, and now DL's schedule shows CRJ's on the route they would fly out of here (BDL-JFK).

[LRJet Guy]

Mesa's always stellar performance, coupled with problems getting the aircraft into service caused DL to pull the plug on the Dashes. Big Sky is flying 1900s on a lot of the former Dash hauls, along with RJ's.

All 8 airplanes are parked at CAE. (or at least they were the last time I was there)

I really think it's a shame. I've got 3000+ hours in the Dash. For winter flying in the Northeast, there's no other airplane I'd rather have under me, even if it is a crappy -100.

[Crism]

LRJet...where will you be going next?

And also, the Freedom Dashes were replaced by ERJs at PVD...then by Comair's CRJ100/200s to JFK. I still hate that airport...

[LRJet Guy]

Heading to NetJets. Been assigned the Citation X.

[Crunk415balla]

Heading to NetJets. Been assigned the Citation X.

Congrats on landing a spot at NetJets!

Thanks for the info, MCM.

[Bok269]

Heading to NetJets. Been assigned the Citation X.

Congrats!

Netjets is A great place to be right now from what I hear.

[Crism]

Heading to NetJets. Been assigned the Citation X.

Holy......When do you start that? If possible, provide all the pics you can. That must be awesome.

[LRJet Guy]

Thanks guys. It's going to be nice having a job I enjoy at a good company.

I'll take the camera on a few trips. I've got a few hundred shots from Piedmont I'm going to upload somewhere when I have the chance. Will do the same when I get comfortable enough with the airplane.