Old Aircraft And Lack Of INS

My dad flew 727s in the 1970s and 1980s. He’s told me that one’s course was maintained by manually dialing-in the VOR frequency and turning the heading bug so that it was aligned with the needle. The only autopilot modes were heading select and altitude hold. The airplane was hand-flown up to the cruising altitude, and again from descent onto the ground.

He advised me that today, however, most airlines that operate 727s, DC-9s, DC-8s, etc. will have upgraded their aircraft with FMCs and Inertial Navigation Systems. Can anyone comment as to whether or not such modifications have been widespread amongst airlines in the developed world, that still operate such aircraft? Furthermore, after an FMC and INS were installed, would an autopilot mode (something akin to modern-day LNAV and VNAV) have been added as well, so that the lateral/vertical course could be tracked?

Lastly, i’m only vaguely aware of what navigational methods long-range aircraft such as the DC-8 and 707 used when flying over vast distances of water, where there were no navaids. Could anyone elaborate? Were such navigation systems installed on the 727, 737-200, and other aircraft that were intended to be “short range”? Or was it just assumed that they would never cross vast waters?

It’s called a FMS- (Flight Management system) and most are now GPS.

Modern day aircraft have 3 axis autopilots that can track a nav course along with a Glide slope.

Over water ops are done with an INS or most likely GPS. I don’t know about the ETOPS of a 737-200 but it could cross the pond no problem.

I was referring to major airlines that today operate old aircraft, like the DC-8 and 727. Examples being FedEx and UPS. Obviously, i’m aware of the equipment on modern aircraft.

UPS DC-8’s were retired earlier this year. However, those aircraft and the 727’s that you mention had been upgraded with newer more advanced navigation technologies. Those older aircraft have been retired from passenger service in the US for some time now. Some of NWA’s (Delta) older DC-9’s have fewer upgrades and several may still be navigating the old VOR to VOR way.

WAIT- i heard Delta (it might have been a different carrier) last week given direct Rocket and they came back Non-GPS need vectors. I posted about this.

And sorry to the OP- I guess I didn’t understand your question. And Azav8r got it right most have been upgraded.

Prolly one of them old NWA “Diesel Nines”. :wink:

NW DC9’s have decently upgraded FMS’s

I believe they were done in the late 90’s around the time of the cabin upgrades.

…and I assume that along with the FMSs, some autopilot mode akin to LNAV and VNAV was also added? It seems like it would be pretty difficult to add autopilot modes to an airplane with which it was not originally equipped.

Incidentally, UPS still operates 44 DC-8s. They are not retired.


Probably no update to the Auto pilot. The FMS would most likley give VNAV prompting to the flight director but no auto pilot coupling.

I flew a Lear with updated Dual FMS & IRS. but we still had the OLD FC200 autopilot. The FMS did all the fancy stuff and gave us Comands via the Flight director but coupling was course only.

“Incidentally” you are incorrect. They HAVE been retired from UPS’ fleet!


Yeah, sorry about that. I read Wikipedia as the gospel.

Check out this picture of a 727 FedEx cockpit: airliners.net/photo/FedEx-Ex … -233-Adv(F/1011314/L/&sid=d6a7c9accee295530f0b57712ea1646e

What is that glass display on the lower center console? It has no keypad, so obviously not an FMC. It couldn’t be a factory-issue, though.

Cutting through the BS of my original post, an appropriate question and topic of discussion would be: Have major airlines that operate old aircraft retrofitted them with FMCs and INSs, and have they also added an autopilot mode that has the ability to couple with the INS course?

Thanks for your responses, everyone. I’m really intrigued by the fact that these old aircraft are still flying, and it warms my heart when I hear news like the fact that NW may be updating the flight decks on their DC-9-50s and keeping them in service for even longer. Conversely, it makes me very sad when, for example, I see P&W destroy a perfectly good 707 on the ramp.

That would be the weather radar display.

It would really surprise me if Delta keeps the old NWA DC-9’s around much longer…let alone spend money on any upgrades. Delta retired the last of its MD-80’s prior to the DAL/NWA merger because they had higher operational costs than the 737 NG’s that have replaced them. As DAL continues to take delivery of new 737NG’s and as the new merged carrier pares down capacity to meet market demand/route overlap, there isn’t much of a place for the old inefficient/maintenance costly DC-9’s in the fleet.

Honeywell scrapped their 720 on their ramp last year.

Delta still hasn’t retired the “last” of its MD-80’s.

In fact it still has over 100 of them.

Where the heck are you getting your “facts”?

Ooooppps! :blush: That is correct. I had a slight bout of halfheimers… :wink: I was thinking Continental…which has retired its MD-80’s.

And I’ve contributed enough useful and accurate information around here to be allowed an occasional slip there… drdique!

Yeah, he’s contributed some useful information.

I get a lot of my “facts” about the industry from my father, who was the Chief Pilot for a major U.S. airline in two cities, simultaneously. At one time, he was also the head of the airline’s training department. I really don’t know what the hell I’m talking about. I’m just a student pilot.

Our G2 has the same autopilot that most of the 60s-70s airline aircraft came with, namely the Sperry SP-50G. We have heading, turn and can track VOR, ILS (LOC alone or LOC and GS) and “aux” which in our case is INS. Until it was updated to meet RVSM requirements it did not have an altitude capture mode, but now it will do that too. The part we have to really be careful with is the Flight Director is not part of the autopilot system, we can be watching one mode on the FD while the autopilot is doing something else.

John in Saudi